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Management of Temporal Bone Malignancy Essay Submitted for Partial Fulfillment of Master Degree in Otorhinolaryngology By Ahmed Fathy Mohamed Eldehn (M.B.B.Ch, Faculty of Medicine - Cairo University) Under the supervision of Prof. Ismail Zohdi Professor of Otorhinolaryngology Faculty of Medicine Cairo University Prof. Louay El Sharkawy Professor of Otorhinolaryngology Faculty of Medicine Cairo University Dr. Baher Ashour Lecturer of Otorhinolaryngology Faculty of Medicine Cairo University 2010 ACKNOWLEDGEMENTS Above all, I would like to thank GOD who made all things possible. He is always there for me throughout my life. Without him, I could not have completed this work. I would like to acknowledge and extend my heartfelt gratitude to the following persons who have made the completion of this work possible. This work would not have been possible without the help, support and patience of my principal supervisor, Prof. Ismail Zohdi, Professor of Otolaryngology, Faculty of Medicine, Cairo University, not to mention his advice, vital encouragement and support. The good advice, support and friendship of my second supervisor, Prof. Louay El Sharkawy, Professor of Otolaryngology, Faculty of Medicine, Cairo University, has been invaluable on both an academic and a personal level, for which I am extremely grateful. Many thanks for my third supervisor, Dr. Baher Ashour, Lecturer of Otolaryngology, Faculty of Medicine, Cairo University, for his understanding, assistance and expert guidance. Also my parents that have given me their obvious support and love throughout my life for which my mere expression of thanks does not suffice. I also thank all the professors in the Otolaryngology Department, Faculty of Medicine, Cairo University, for their support and assistance since the start of my residency in 2006. Last, but by no means least, I would like to thank my colleagues and my friends for their kindness, friendship, encouragement and support. My apologies if I have accidentally omitted anyone to whom acknowledgement is due. Thank you Contents Anatomy of the Temporal Bone 1 Pathology of Temporal Bone Malignancy 22 Squamous cell and basal cell carcinoma Malignant Melanoma Merkel-cell carcinoma Adenexal carcinoma of the ear Sarcomas of the ear Endolymphatic sac tumor Multiple myeloma, and plasmacytoma of the middle and inner ear Lymphoma of the temporal bone Metastatic carcinoma of temporal bone Patterns of Spread Staging Systems 24 26 27 28 32 36 38 40 41 42 44 Clinical Assessment of Temporal Bone Malignancy 46 Radiological Diagnosis of Temporal Bone Malignancy 49 Computed Tomography of the temporal bone Magnetic resonance imaging of the temporal bone Registration and Fusion of CT and MRI Of the Temporal Bone Surgical Management of Temporal Bone Malignancy Lateral temporal bone resections Subtotal Temporal bone resection Total Temporal Bone Resection Reconstruction after temporal bone surgery Complications of temporal bone resection 49 58 63 66 71 76 80 82 84 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy 86 Prognosis & Outcome of Temporal Bone Malignancy 102 Report of a case 107 Summary 113 References 116 I List of Abbreviations EAC TMJ IAC V VIII IX X XI XII CEV IPS AIDS ICA CT PACS 3D MRI CSF PT MT PosT SE 192 Ir Gy MeV MV LINAC APS EBRT LTBR STBR TTBR External Auditory Canal Temporo-Mandibular Joint Internal auditory canal Trigeminal Vestibulo-Cochlear Glossopharyngeal Vagus Accessory Hypoglossal Condylar emissary vein inferior petrosal sinus Acquired Immune Deficiency Syndrome Internal carotid artery Computed Tomography picture archiving and communications systems 3 Dimension Magnetic Resonance Imaging Cerebrospinal fluid Protympanum Mesotympanum Posterior tympanum Spin Echo Iriduim Grey Mega electron volt Mega volt linear accelerator automated positioning system External beam radiation therapy Lateral temporal bone resection Subtotal temporal bone resection Total temporal bone resection II List of Figures Number of figure 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. Title Page Lateral view, left temporal bone. Medial view, left temporal bone. Superior view, left temporal bone. Inferior view, The tympanic membrane Schematic view of the middle ear cleft. Internal auditory canal. The view of cranial nerves IX, X, and XI after removal of the medial wall of the jugular bulb Intracranial view of the posterior surface of the petrous bone showing cranial nerves V, VIII, IX, X, XI, and XII. Merkel-cell carcinoma of the antitragus in a 72-year-old man. Glandular tumors (microscopic picture) Embryonal rhabdomyosarcoma Chondrosarcoma Kaposi’s sarcoma of a 23-year-old man with AIDS Histopathologic examination of endolymphatic sac tumor Plasma cell tumor Coronal anatomy of pathways of spread of primary cancer of the external auditory canal. Photograph of the left ear shows a tumor extruding from the External auditory canal Sensation 64 scanner equipped with 32 detectors and two sources Axial CT image at the level of the left temporomandibular joint demonstrating the S-shape and the junction of the cartilaginous and bony portions of the external auditory canal Coronal CT image at the mid bony portion of the left external auditory canal. Axial CT images of the right middle and inner ear from caudal to cephalic Axial CT images of the right middle and inner ear from caudal to cephalic Axial CT images of the right middle and inner ear from caudal to cephalic Oblique coronal CT scan shows an extensive destructive lesion of the left temporal bone with mottled calcification An endolymphatic sac tumor. CT scan reveals the tumor extensions An MRI scanner. 2 4 6 8 9 12 17 III 18 20 28 31 33 34 36 38 39 43 47 50 52 52 55 55 56 57 57 59 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. Magnetic resonance imaging of the internal acoustic canal Rhabdomyosarcoma Adenoid cystic carcinoma Registration and Fusion of CT and MRI Of the Temporal Bone Types of temporal bone resections lateral temporal bone resection type I lateral temporal bone resection type II lateral temporal bone resection type III lateral temporal bone resection type IV A: Incisions vary according to whether the tumor is contained in the temporal bone. B: The facial nerve can be divided peripherally at the distal branches or centrally at the facial nerve trunk, depending on involvement of the parotid gland. C: After osteotomies and removal of the zygomatic arch and mandibular segments, dissection in the infratemporal fossa continues (A) Incision marked out for extended temporal bone excision. (B) First step is to place colored slings around the great vessels in order to ensure vascular control and identify cranial nerves IX, X, XI, and XII prior to completing the supra-omohyoid neck dissection. (C) Wide access and good visualization of the jugular and carotid foramina and skull base is essential before completing the en bloc extended temporal bone excision. (D) View of the large defect on completion of the resection Example of treatment portal for tumor of the middle ear involving the petrous bone. Radiation technique for treatment of T3N1 carcinoma of the external auditory canal Dose distribution for brachytherapy treatment of EAC recurrence. Stereotactic radiosurgery technique John Adler and the Cyberknife Lateral extent of the mass in the case report Operative view showing markings before the incision Intraoperative view showing the incision. Intraoperative view showing anterior and posterior flap elevations. Intraoperative view after neck dissection and temporal craniotomy. Intraoperative view after resection The specimen (lateral aspect). Immediate postoperative view. IV 60 61 62 65 67 72 73 74 75 79 81 90 92 93 98 99 107 108 108 109 109 110 111 111 Anatomy of The Temporal Bone Anatomy of The Temporal Bone The temporal bone is a composite structure consisting of the tympanic bone, mastoid process, squama (also known as the squamous portion of the temporal bone), and petrosa (also known as the petrous portion of the temporal bone). Although the styloid process is closely related to the temporal bone, it is not considered a portion of it (Gulya and Schuknecht, 2007). External Auditory Canal (EAC) EAC is a part of the external ear transmitting sounds from the auricle to the tympanic membrane; the lateral one-third of the EAC comprises a continuation of the cartilage of the pinna and is deficient superiorly at the incisura terminalis. The two or three variably present perforations in the anterior aspect of the cartilaginous canal are the fissures of Santorini. The remaining medial two-thirds of the approximately 2.5-cm length of the canal are bony. The isthmus is the narrowest portion of the EAC. It lies just medial to the junction of the bony and cartilaginous canals. The skin of the cartilaginous canal has a substantial subcutaneous layer contains hair follicles, sebaceous glands, and cerumen glands. The skin of the osseous canal is very thin and its subcutaneous layer is devoid of the usual adnexal structures. Accordingly, the absence of hair serves to distinguish the bony and cartilaginous canals (Saleh et al., 1995). The pinna and EAC are supplied by a variety of sensory nerves. The auriculotemporal branch of the trigeminal nerve, greater auricular nerve (a branch of C3), lesser occipital nerve (of C2 and C3 derivation), auricular branch of the vagus nerve (Arnold’s nerve), and twigs from the facial nerve Management of Temporal Bone Malignancy 1 Anatomy of The Temporal Bone all contribute to the sensory innervation of the pinna and EAC (Eshraghi et al., 2001). The tympanic, squamous, and mastoid portions of the temporal bone are evident on the lateral view. Figure 1: Lateral view, left temporal bone. The temporal line, extending posteriorly from the root of the zygoma, approximates the inferior descent of the dura medially as well as the inferior attachment of the temporalis muscle laterally. 1- squama, 2- temporal line, 3 -mastoid fossa, 4- Henle’s spine, 5- tympanosquamosal suture, 6- mastoid foramen, 7- mastoid process, 8- external auditory canal, 9- zygoma, 10- petrotympanic fissure, 11- tympanic bone, 12- mandibular fossa, 13 – styloid process. (Gulya and Schuknecht, 2007). The tympanic bone forms the anterior, inferior, and parts of the posterior wall of the EAC. It interfaces with the squama at the tympanosquamous suture, the mastoid at the tympanomastoid suture, and the petrosa at the petrotympanic fissure and constitutes the posterior wall of the Management of Temporal Bone Malignancy 2 Anatomy of The Temporal Bone glenoid fossa for the temporo mandibular joint (TMJ). The tympanomastoid suture is traversed by Arnold’s nerve, while the chorda tympani nerve and anterior tympanic artery traverse the petrotympanic fissure. Henle’s spine is a projection of variable prominence at the posterosuperior aspect of the EAC. Inferiorly, the vaginal process, a projection of the tympanic bone, forms the sheath of the styloid bone. Laterally, the tympanic bone borders the cartilaginous EAC, whereas medially it bears a circular groove, the annular sulcus. The annular sulcus houses the annulus of the tympanic membrane except superiorly, where it is deficient; at this point, known as the notch of Rivinus, the tympanic membrane attaches directly to the squama (Hughes and Pensak, 1997). The squamous portion of the temporal bone serves as the lateral wall of the middle cranial fossa and interfaces with the parietal bone superiorly and with the zygomatic process and the sphenoid anteriorly. Its medial surface is grooved by a sulcus for the middle meningeal artery, whereas the middle temporal artery runs in a groove on its lateral aspect (Hughes and Pensak, 1997). Management of Temporal Bone Malignancy 3 Anatomy of The Temporal Bone Figure 2: Medial view, left temporal bone. The meeting of the posterior and middle fossa faces of the temporal bone occurs at the sulcus for the superior petrosal sinus. 1 – Superior petrosal sulcus, 2 – arcuate eminence, 3 – squama, 4 – sigmoid sulcus, 5 – petromastoid canal, 6 – middle meningeal artery sulcus, 7 – internal auditory canal, 8 – petrous apex, 9 – styloid process, 10 – internal carotid artery foramen. (Gulya and Schuknecht, 2007). The mastoid portion of the temporal bone is the inferiorly extending projection seen on the lateral surface of the temporal bone. It is composed of a squamous portion (laterally) and a petrous portion (medially) separated by Korner’s (petrosquamous) septum. The fossa mastoidea (MacEwen’s triangle) is defined by the linea temporalis (temporal line), a ridge of bone extending posteriorly from the zygomatic process (marking the lower margin of the temporalis muscle and approximating the inferior descent of the middle cranial fossa dura), the posterosuperior margin of the EAC, and a tangent to the posterior margin of the EAC. The fossa mastoidea, a cribrose (cribriform) area, is identified by its numerous, perforating small blood Management of Temporal Bone Malignancy 4 Anatomy of The Temporal Bone vessels. The mastoid foramen, located posteriorly on the mastoid process, is traversed by the mastoid emissary vein and one or two mastoid arteries. Inferiorly, the sternocleidomastoid muscle attaches to the mastoid tip. The fossa mastoidea is an important surgical landmark as it laterally overlies the mastoid antrum. The mastoid antrum, medial to the fossa mastoidea (Macewen’s triangle), develops in the earliest stages of mastoid pneumatization and is ordinarily present in even the least pneumatized temporal bones (Gulya and Schuknecht, 2007). The petrosa; the term “petrous” (Greek for “rocklike”) stems from the extreme density of its bone, which guards the sensory organs of the inner ear. Important landmarks seen on a superior view are the arcuate eminence (roughly corresponding to the superior semicircular canal), meatal plane (indicative of the internal auditory canal), foramen spinosum for the middle meningeal artery, and facial hiatus (marking the departure of the greater petrosal nerve from the anterior aspect of the geniculate ganglion). The lesser petrosal nerve, accompanied by the superior tympanic artery occupies the superior tympanic canaliculus, lying lateral to and paralleling the path of the greater petrosal nerve to the petrous apex. The petrous apex points anteromedially and is marked by the transition of the intrapetrous to the intracranial internal carotid artery, orifice of the bony eustachian tube, and, anterolaterally, ganglion of the trigeminal nerve in Meckel’s cave. The medial aspect of the temporal bone features the porus of the internal auditory canal (IAC). Also the petrous apex shows the internal carotid foramen, by which the internal carotid artery exits the temporal bone (Saleh et al., 1995). Management of Temporal Bone Malignancy 5 Anatomy of The Temporal Bone The sigmoid portion of the lateral venous sinus runs in a deep sulcus posteriorly, whereas the superior petrosal sinus runs in the sulcus located at the junction of the posterior and middle fossa faces of the temporal bone. The vertically oriented posterior face of the petrosa dominates the posterior view of the temporal bone as it delimits the anterolateral aspect of the posterior cranial fossa and lies between the superior and inferior petrosal sinuses. The porus of the IAC, operculum, endolymphatic fossette cradling the endolymphatic sac, and subarcuate fossa are the key anatomical features on this surface (Eshraghi et al., 2001). Figure 3: Superior view, left temporal bone. The pyramidal shape of the petrous bone is well shown in this view. 1 – Zygoma, 2 – tegmen, 3 – arcuate eminence, 4 – lesser superficial petrosal canal, 5 – internal carotid artery foramen, 6 – internal auditory canal, 7 – facial hiatus, 8 – petrous apex. (Gulya and Schuknecht, 2007). The inferior surface of the temporal bone figures prominently in skull base anatomy as it interfaces with the sphenoid and occipital bones. It provides attachment for the deep muscles of the neck and is perforated by a Management of Temporal Bone Malignancy 6 Anatomy of The Temporal Bone multitude of foramina. The jugular fossa, housing the jugular bulb, is separated from the internal carotid artery by the jugulocarotid crest. The aperture of the inferior tympanic canaliculus traversed by the inferior tympanic artery and the tympanic branch of the glossopharyngeal nerve (Jacobson’s nerve), is located in the jugulocarotid crest, whereas the cranial aperture of the cochlear aqueduct is located anteromedial to the jugular fossa. The stylomastoid foramen of the facial nerve is located just posterior to the styloid process. The occipital artery and the digastric muscle occupy the temporal groove and the mastoid incisure, respectively, at the medial aspect of the tip. The jugular foramen is of particular importance in skull base surgery as it is traversed by the glossopharyngeal (IX), vagus (X), and spinal accessory (XI) cranial nerves as they exit the skull (Kveton et al., 1996). The cochlear aqueduct, carrying the periotic (or perilymphatic) duct, is an important landmark for the neurootologist. As the cochlear aqueduct runs from the medial aspect of the scala tympani of the basal cochlear turn to terminate anteromedial to the jugular bulb, it parallels, and lies inferior to, the IAC. In addition, cranial nerve IX, the inferior petrosal sinus, and, in some cases, cranial nerves X and XI can be found immediately inferior to the lateral terminus of the cochlear aqueduct (Aslan et al., 1998). Management of Temporal Bone Malignancy 7 Anatomy of The Temporal Bone Figure 4: Inferior view, left temporal bone. This view shows the topographically intricate inferior surface of the temporal bone. 1 – Inferior petrosal sulcus, 2 – cochlear aqueduct, 3 – inferior tympanic canaliculus, 4 – jugulocarotid crest, 5 – internal carotid artery foramen, 6 – jugular fossa, 7 – sigmoid sulcus, 8 – mandibular fossa, 9 – temporal groove, 10 – mastoid incisure, 11 – mastoid tip, 12 – stylomastoid foramen, 13 – styloid process. (Gulya and Schuknecht, 2007). Related Structures The Tympanic Membrane The tympanic membrane is irregularly round and slightly conical in shape; the apex of the cone is located at the umbo, which marks the tip of the manubrium. In the adult, it is angulated approximately 140° with respect to the superior wall of the external auditory canal. The vertical diameter of the tympanic membrane as determined along the axis of the manubrium ranges from 8.5 to 10 mm, while the horizontal diameter varies from 8 to 9 mm. Management of Temporal Bone Malignancy 8 Anatomy of The Temporal Bone The malleal prominence, a projection formed by the lateral process of the malleus, is located at the superior end of the manubrium. Figure 5: The tympanic membrane. (Gulya and Schuknecht, 2007). The manubrium is firmly attached to the tympanic membrane at the umbo and lateral process and is clearly visible throughout its length (the stria mallearis). The anterior and posterior tympanic striae extend from the lateral process of the malleus to the anterior and posterior tympanic spines, respectively. These striae divide the tympanic membrane into larger pars tensa below, and smaller triangular pars flaccida (or Shrapnell’s membrane) above. The superior recess of the tympanic membrane is known as Prussak’s space. The pars flaccida forms the lateral border of this space as it attaches superiorly to the bony margins of the notch of Rivinus or tympanic incisura. The lateral malleal ligament limits this space anterosuperiorly as it extends Management of Temporal Bone Malignancy 9 Anatomy of The Temporal Bone from the union of the head and neck of the malleus to the periphery of the notch of Rivinus. Posteriorly, Prussak’s space opens into the epitympanum. The anterior and posterior malleal folds mark the inferior limit of Prussak’s space. The thickened periphery of the pars tensa, the tympanic annulus (limbus), anchors the tympanic membrane in a groove known as the tympanic sulcus. The tympanic annulus and sulcus are absent superiorly in the area of the notch of Rivinus. The pars tensa and pars flaccida differ in structure. The pars tensa consists of three layers: lateral epidermal layer, medial mucosal layer, and intermediate fibrous layer, the pars propria (Gulya and Schuknecht, 2007). Ossicles The ossicular chain made up of the malleus, incus, and stapes, serves to conduct sound from the tympanic membrane to the cochlea. The malleus is the most lateral of the ossicles, has a head (caput), manubrium (handle), neck, and anterior and lateral processes. The lateral process has a cartilaginous “cap” that imperceptibly merges with the pars propria of the tympanic membrane. The incus, the largest of the three ossicles, is immediately medial to the malleus. The incus has a body and three processes: a long, a short, and a lenticular process. The body of the incus articulates with the head of the malleus in the epitympanum. The short process of the incus is anchored in the incudal fossa by the posterior incudal ligament. The long process extends inferiorly, roughly paralleling and lying posterior to the manubrium. The lenticular process, at the terminus of the long process, articulates with the stapes. The stapes is the smallest and most Management of Temporal Bone Malignancy 10 Anatomy of The Temporal Bone medial of the ossicles. Its head articulates with the lenticular process of the incus, whereas its foot plate sits in the oval window, surrounded by the stapedo-vestibular ligament. The arch of the stapes, composed of an anterior and a posterior crura, links the head and the foot plate (Sanna et al., 1980). Middle Ear Muscles The tensor tympani muscle, innervated by the trigeminal nerve, originates from the walls of its semicanal, greater wing of the sphenoid, and cartilage of the eustachian tube. The tendon of the tensor tympani muscle sweeps around the cochleariform process and across the tympanic cavity to attach to the medial aspect of the neck and manubrium of the malleus. The medial pull of the tensor tympani muscle is ordinarily opposed by the intact tympanic membrane. The stapedius muscle runs in a vertical sulcus in the posterior wall of the tympanic cavity adjacent to the facial nerve, from which it receives its innervation. Its tendon traverses the pyramidal eminence to attach to the posterior crus, and occasionally the head, of the stapes (Keles et al., 2009). Management of Temporal Bone Malignancy 11 Anatomy of The Temporal Bone Figure 6: Schematic view of the middle ear cleft. (Gulya and Schuknecht, 2007). Middle Ear Spaces The tympanic cavity is a sagittally oriented slit that lies immediately medial to the tympanic membrane. Its roof or tegmen, also serves as a part of the floor of the middle cranial fossa, whereas its irregularly contoured floor features the jugular bulb and, posteriorly, the root of the styloid process. The tympanic cavity is in continuity with the eustachian tube anteriorly and with the mastoid air cells via the aditus ad antrum posteriorly. It is traversed by the ossicular chain and is lined with a mucosal epithelium. Planes extended from the tympanic annulus subdivide the tympanic cavity into a mesotympanum, hypotympanum, protympanum, and posterior Management of Temporal Bone Malignancy 12 Anatomy of The Temporal Bone tympanic cavity. The epitympanum lies above the plane of the anterior and posterior tympanic spines. Anteriorly, the mesotympanum is dominated by the bulge of the semicanal of the tensor tympani muscle; the tympanic orifice of the eustachian tube is immediately inferior to this bulge. Posteriorly, the key anatomical feature is the pyramidal eminence and, lateral to it, the chordal eminence. The medial wall (the surgical “floor” of the middle ear) features three depressions: the sinus tympani, oval window niche, and round window niche (Glasscock and Gulya, 2007). The sinus tympani is defined by the ponticulus superiorly, the subiculum inferiorly, the mastoid segment of the facial nerve laterally, and the posterior semicircular canal medially; there is substantial variability in the posterior extension (surgical “depth”) of the sinus tympani, ranging from “shallow” to “deep.” The oval window niche, occupied by the stapes footplate, is located anterosuperior to the ponticulus. The round window niche can be found posteroinferior to the promontory, the bulge created by the basal turn of the cochlea (Nomura et al., 1984) Eustachian Tube The eustachian tube extends approximately 35 mm from the anterior aspect of the tympanic cavity to the posterior aspect of the nasopharynx and serves to ventilate, clear, and protect the middle ear. The lining mucosa of the tube has an abundance of mucociliary cells, important to its clearance function. The anteromedial two-thirds of the eustachian tube are fibrocartilaginous, whereas the remainder is bony. The tympanic orifice is in the anterior wall of the middle ear, a few millimeters above the floor (Glasscock and Gulya, 2007). Management of Temporal Bone Malignancy 13 Anatomy of The Temporal Bone Pneumatization The extent of pneumatization of the temporal bone varies according to heredity, environment, nutrition, infection, and eustachian tube function. There are five recognized regions of pneumatization: the middle ear, mastoid, perilabyrinthine, petrous apex, and accessory cells. The mastoid region is subdivided into the mastoid antrum, central mastoid, and peripheral mastoid. The bony labyrinth divides the perilabyrinthine region into supralabyrinthine and infralabyrinthine areas. The apical area and the peritubal area comprise the petrous apex region. The accessory region encompasses the zygomatic, squamous, occipital, and styloid areas (Nadol and Schuknecht, 1993). There are five recognized air cell tracts. The posterosuperior tract runs at the junction of the posterior and middle fossa aspects of the temporal bone. The posteromedial cell tract parallels and runs inferior to the posterosuperior tract. The subarcuate tract passes through the arch of the superior semicircular canal. The perilabyrinthine tracts run superior and inferior to the bony labyrinth, whereas the peritubal tract surrounds the eustachian tube. The anterior petrous apex is pneumatized in only 10 to 15% of specimens studied. Most often, it is diploic; and in a small percentage of cases, it is sclerotic (Saim et al., 1996). Inner Ear The bony labyrinth houses the sensory organs and soft tissue structures of the inner ear and consists of the cochlea, three semicircular canals, and vestibule. The cochlea spirals 2.5 turns about its central axis, and Management of Temporal Bone Malignancy 14 Anatomy of The Temporal Bone has a height of 5 mm. The base of the cochlea touches the fundus of the IAC and is perforated (cribrose), allowing for the passage of cochlear nerve fibers. The apex lies medial to the tensor tympani muscle. The osseous spiral lamina winds about the modiolus and along the basilar membrane, separates the scala media (the cochlear duct) from the scala tympani. Adjacent turns of the cochlea are separated by an interscalar septum (Glasscock and Gulya, 2007). The three semicircular canals are the lateral (horizontal), superior (anterior vertical), and posterior (posterior vertical). The three canals are orthogonally related to one another and arc over a span of 240 degrees. Each canal has an ampullated limb, measuring 2 mm in diameter, and a nonampullated limb, which is1 mm in diameter. The ampulla is cribrose for passage of nerve fibers. The non-ampullated limbs of the posterior and superior canals fuse to form the crus commune. The ampullated and nonampullated limbs all open into the vestibule. The angle formed by the three semicircular canals is the solid angle, whereas the triangle bounded by the bony labyrinth, sigmoid sinus, and superior petrosal sinus is known as Trautmann’s triangle (Carey et al., 2000). The vestibule is the central chamber of the bony labyrinth and measures 4 mm in diameter. Its medial wall is marked by depressions for the saccule (the spherical recess), utricle (the elliptical recess), and cochlear duct (the cochlear recess). Cribrose areas accommodate nerve fiber access to their sensory organs. “Mike’s dot” (the macula cribrosa superior) marks the passage way for superior vestibular nerve fibers to the cristae ampullares of the lateral and superior semicircular canals. As it corresponds to the extreme lateral aspect of the IAC, Mike’s dot is an important landmark in transManagement of Temporal Bone Malignancy 15 Anatomy of The Temporal Bone labyrinthine surgery. There are three fissures of the bony labyrinth. The fissula ante fenestram is an invagination of the perilymphatic space that is invariably found extending anterosuperior to the oval window; in the adult, fibrous tissue and cartilage fill the fissula. The fissula post fenestram is a perilymphatic evagination that extends posterior to the oval window; it is a less constant feature of the temporal bone (Gacek et al., 1979). The membranous (endolymphatic) labyrinth housed within the bony labyrinth consists of the cochlear duct (scala media), the three semicircular ducts and their cristae ampullares, the otolithic organs (the utricle and the saccule), and the endolymphatic duct and sac. The endolymphatic duct originates in the medial wall of the vestibule. It first parallels the crus commune and then the posterior semicircular canal as it heads to the endolymphatic sac, anterior and medial to the sigmoid sinus. The endolymphatic sac lies approximately 10 mm inferior and lateral to the porus of the IAC; the sac has an intraosseous portion, which is covered by the operculum, and a more distal intradural portion (Glasscock and Gulya, 2007). Internal Auditory Canal (IAC) The IAC is the bony channel that shelters the superior and inferior vestibular, cochlear, facial, and intermediate nerves, as well as the labyrinthine artery and vein, as they course from the posterior cranial fossa to the labyrinth. On average, the canal measures 3.4 mm in diameter and 8 mm in length; these dimensions display considerable interindividual variability. The porus is the posterior cranial fossa opening of the canal, whereas the canal abuts the bony labyrinth at its fundus. At the fundus, the Management of Temporal Bone Malignancy 16 Anatomy of The Temporal Bone vestibular, facial, and cochlear nerves are in a constant anatomic relationship that is determined by the horizontal (falciform) crest and the vertical crest (“Bill’s bar”) (Naguib et al., 1994). Figure 7: Internal auditory canal. (Glasscock and Gulya, 2007). Management of Temporal Bone Malignancy 17 Anatomy of The Temporal Bone Neuroanatomy Figure 8: The view of cranial nerves IX, X, and XI after removal of the medial wall of the jugular bulb. A fibrous septum separates cranial nerve IX from cranial nerves X and XI. The opening of the condylar emissary vein (CEV) is seen in the posteroinferior portion of the JB. The orifice of the inferior petrosal sinus (IPS) is seen posterior to cranial nerves X and XI. Cranial nerve XII is depicted exiting its foramen. (Keles et al., 2009). Trigeminal and Abducent Nerves The gasserian ganglion of the trigeminal nerve occupies Meckel’s cave on the middle cranial fossa face of the temporal bone, anterolateral to the petrous apex. The abducent (sixth cranial) nerve runs in Dorello’s canal beneath the posterior petroclinoid (Gruber’s) ligament (Moreano et al., 1994). Facial Nerve The course of the facial nerve is divided into five segments. Its intracranial segment stretches 24 mm from the pons to the porus of the IAC. The intracanalicular segment traverses the IAC; at the fundus, it occupies the anterosuperior quadrant, where it is joined by the nervus intermedius. The shortest segment is the labyrinthine segment, running 4 mm from the Management of Temporal Bone Malignancy 18 Anatomy of The Temporal Bone beginning of the fallopian canal to the geniculate ganglion. The tympanic segment is roughly 13 mm long and courses in the medial wall of the tympanic cavity, superior to the cochleariform process and oval window. The mastoid segment spans the 20-mm distance from the second genu (at the lateral semicircular canal) to the stylomastoid foramen (Procter et al., 1982). There are three intratemporal branches of the facial nerve: the greater petrosal nerve, nerve to the stapedius muscle, and chorda tympani nerve. The nervus intermedius (nerve of Wrisberg) carries the taste, secretory, and sensory fibers of the facial nerve. In the IAC, the nervus intermedius runs as a separate nerve between the facial and superior vestibular nerves. In the temporal bone, the nervus intermedius is within the facial nerve, occupying its dorsal aspect in the tympanic segment and its posterolateral aspect in the mastoid segment. The chorda tympani nerve represents the separation of the sensory fibers at the inferior mastoid segment (Gacek, 1998). Cochlear Nerve The cochlear nerve arises from the spiral ganglion neurons. At the fundus of the IAC, the cochlear nerve is in the anteroinferior compartment. It rotates as it heads toward the porus and enters the brainstem a few millimeters caudal to the root entry zone of the trigeminal nerve (Glasscock and Gulya, 2007). Vestibular Nerves The superior and inferior vestibular nerves occupy the posterior half of the IAC. The structures innervated by the superior vestibular nerve are the superior and lateral semicircular canals, utricular macula, and superior Management of Temporal Bone Malignancy 19 Anatomy of The Temporal Bone portion of the saccular macula. The inferior vestibular nerve innervates the inferior saccular macula and, by its posterior ampullary branch, the posterior semicircular canal. The posterior ampullary nerve separates from the main trunk of the inferior vestibular nerve a few millimeters from the porus of the IAC and traverses the singular canal to the posterior canal ampulla (Eshraghi et al., 2001). Figure 9: Intracranial view of the posterior surface of the petrous bone showing cranial nerves V, VIII, IX, X, XI, and XII. The glossopharyngeal and vagal meatus are separated by a dural septum. Cranial nerve IX enters the glossopharygal meatus, whereas cranial nerve X and cranial nerve XI enter the vagal meatus. (Keles et al., 2009). Management of Temporal Bone Malignancy 20 Anatomy of The Temporal Bone Vascular Anatomy Temporal Bone Arteries The internal carotid artery enters the temporal bone through the external carotid foramen, located just anteromedial to the styloid process. As it ascends in its intrapetrous segment, it passes first anterior to the tympanic cavity and cochlea and then bends (its “knee”) to run medial to the eustachian tube and inferomedial to the semicanal of the tensor tympani muscle. The artery climbs to exit the temporal bone at the internal carotid foramen. Accompanying the artery throughout its intrapetrous course are a venous and a neural (sympathetic) plexus. The bony shell protecting the artery is thin (often less than 0.5 mm thick) and can be dehiscent in 6% of cases (Moreano et al., 1994). Temporal Bone Veins The three dominant sinuses of the temporal bone are the sigmoid (portion of the lateral venous sinus), superior petrosal, and inferior petrosal. The lateral venous sinus occupies an S-shaped sulcus in the posterior mastoid (hence the term sigmoid) as it extends from the transverse sinus to the internal jugular vein. This drainage system on the right is larger than that on the left in 75% of cases (Glasscock and Gulya, 2007). The superior petrosal sinus drains the cavernous sinus into the lateral venous sinus as it runs in the superior petrosal sulcus at the junction of the posterior and middle fossa dural plates. The inferior petrosal sinus courses in the petro-occipital suture line. It drains the cavernous sinus into the jugular bulb (Gacek et al., 1992). Management of Temporal Bone Malignancy 21 Pathology of Temporal Bone Malignancy Pathology of Temporal Bone Malignancy The variability of malignant lesions that could arise within the temporal bone is due to the different histological characters of the tissues involved. The external ear consists of the auricle and the external auditory canal; the outer aspect of the tympanic membrane defines its innermost extent. The pinna is mainly composed of a shell of fibrocartilage and is fixed to the skull by skin, cartilage, muscle, and ligamentous tissue. The pinna and external auditory canal are lined by keratinising squamous epithelium with accompanying cutaneous adnexal structures (such as hair follicles and sebaceous glands) (Devaney et al., 2005). Furthermore, the outer portion of the external canal contains variants of the apocrine gland known as ceruminous glands. The pinna and external auditory canal are, in turn, supported by fibrofatty soft tissue, elastic cartilage, and bone. The middle ear is lined by ciliated respiratory-type epithelium (eustachian tube) and by a single layer of cuboidal-to-flattened epithelium (tympanic cavity and mastoid cavity). The inner ear contains both the labyrinth and the eighth cranial nerve (the vestibulocochlear nerve), as it runs through the internal auditory canal. The sensory cells of hearing and balance are found in the labyrinth, bathed in endolymph (a hybrid of extracellular fluid and cerebrospinal fluid) (Devaney et al., 2005). Management of Temporal Bone Malignancy 22 Pathology of Temporal Bone Malignancy The malignant tumors that could arise from the temporal bone are Malignant neoplasms of the external ear Squamous cell carcinoma Basal-cell carcinoma Malignant melanoma Merkel-cell carcinoma Adenexal carcinoma (including ceruminous adenocarcinoma, adenoid cystic carcinoma & mucoepidermoid carcinoma) Angiosarcoma (including both conventional angiosarcoma and Kaposi’s sarcoma) Lymphoma Malignant neoplasms of the middle and inner ear Endolymphatic-sac tumor (aggressive papillary tumor) Squamous cell carcinoma Adenocarcinoma Rhabdomyosarcoma Lymphoma, multiple myeloma, and plasmacytoma Metastatic carcinoma (Barnes et al., 2005) Management of Temporal Bone Malignancy 23 Pathology of Temporal Bone Malignancy Squamous cell and basal cell carcinoma Cutaneous squamous carcinomas and basal cell carcinomas are the most common malignant carcinomas affecting the temporal bone. Although there are distinct light-microscopic differences between squamous and basal-cell carcinomas, the two are considered together here as non-melanomatous cutaneous carcinomas. In the pinna, basal cell carcinomas are about four times more common than squamous carcinomas; however, in the external auditory canal the ratio is reversed. Squamous and basal-cell carcinomas are mainly diseases of older men, diagnosed on average when they are in their 70s (Ahmad &Gupta, 2001). Both carcinomas are closely associated with previous actinic damage to the skin (through exposure to ultraviolet radiation) when they arise in the pinna. However, this association is not seen in lesions of the external auditory canal; squamous cell carcinomas of the external canal are frequently preceded by a few years’ history of a chronic draining otorrhea as in chronic suppurative otitis media which was accepted in the older literature as an obvious etiologic factor (Gacek et al., 1998). The gross appearance of basal cell carcinoma is usually one of a pearly waxlike nodule that eventually ulcerates. Twenty-five percent of basal cell carcinomas of the pinna are of the morphea type. The importance of this variety is that although the edge of the tumor tends to infiltrate subcutaneously, this cannot be recognized clinically or on gross pathological examination. The classical and most frequent form of basal cell carcinoma is composed of solid masses of cells, which Management of Temporal Bone Malignancy 24 Pathology of Temporal Bone Malignancy are seen to be arising from the basal layers of the epidermis or the outer layers of the hair follicles (Vantuchova& Curik, 2006). The cells are uniform with basophilic nuclei and little cytoplasm. At the periphery of the neoplastic lobules the cells tend to be palisaded. Squamous cell differentiation is also common. The cell groups are splitted by hyaline fibrous tissue, so that the carcinoma appears compressed into thin strands; is referred to as the morphea type of basal cell carcinoma. The suggestion that tumors with this histology have a worse outlook is probably related to their tendency towards insidious infiltration. However, when immunohistochemical assessment for Ki-67 antigen (MIB1 in paraffin sections) is performed on basal cell carcinomas, those tumors that recur have been shown to possess a higher proportion of cells positive for that antigen than those that do not (Heiligenhaus et al., 1996) The morphea type of basal cell carcinoma is not an aggressive neoplasm and in at least 90% of cases a 3-year cure can be easily achieved by surgical excision. In a few cases repeated recurrences with deep extension to the middle ear, mastoid and even cranial cavity may, however, take place; although metastasis is rare (Vantuchova& Curik, 2006) The majority of squamous cell carcinomas of the external ear arise in the pinna; a lesser number arise in the external canal. A plaque-like or even polypoid mass may be felt or even seen in the pinna. The appearances of the canal lesions are those of a mass, sometimes warty, occluding the lumen and invading deeply into the surrounding tissues. There may be dissolution of the tympanic membrane with invasion of the middle ear. It usually shows significant degrees of keratinisation. In the cases with a canal origin evidence of origin from canal Management of Temporal Bone Malignancy 25 Pathology of Temporal Bone Malignancy epidermis is usually present. In cases arising deep within the ear canal there is usually a concomitant origin from middle ear epithelium and dissolution of the tympanic membrane. The neoplasm may be so well differentiated that it can be confused with benign papilloma. The association of a well-differentiated squamous carcinoma with marked desmoplasia may also delay the correct diagnosis. The verrucous form of squamous cell carcinoma has been seen in the external ear (Sjo et al., 2001). Metastatic spread of squamous cell carcinoma of the pinna and external auditory meatus to lymph nodes is unusual. Squamous cell carcinoma of the external canal is an aggressive disease with a high propensity towards local recurrence (Prabhu et al., 2009). Both squamous cell carcinomas and basal cell carcinomas can metastasize. Although squamous cell carcinomas give rise to metastases much more commonly than basal cell carcinomas; distant metastases from squamous cell carcinoma of the ear are rare (Sasaki, 2001). Malignant Melanoma Melanotic neoplasms are unusual in the external ear. They usually arise in the auricle; origin in the external canal is extremely unusual. Malignant melanoma of the external ear is a highly aggressive malignant disease. By the time of the diagnosis, patients with malignant melanoma usually are at an advanced stage of the disease (Merchant & Weinstein, 2003). Management of Temporal Bone Malignancy 26 Pathology of Temporal Bone Malignancy It is likely that cervical and parotid gland lymph nodes will be involved when malignant melanoma of the external ear is first diagnosed (Schuster & Seregard, 2003). The external ear accounts for about 10% of all head and neck melanomas. As elsewhere in the body, melanomas of the external ear are associated with previous actinic damage. Men are more affected than women (ratio two to one or three to one); the average age is in the 50s, and most present with a nodular or flattened pigmented lesion. Crucial outcome factors include clinical stage at initial presentation and the microscopical thickness of the lesion (Pockaj et al., 2003). These tumors are aggressive and can spread to regional lymph nodes early in the course of disease. A major drawback is posed by the variability of lymphatic drainage patterns from the ear; the upper cervical region and the lower tail of the parotid gland are most commonly cited as regional draining regions for the lymphatics of the ear (Cole et al., 2003). Merkel-cell carcinoma Merkel-cell carcinomas (cutaneous neuroendocrine carcinomas) are rare, slow-growing subcutaneous nodules that develop in sun-exposed areas in elderly patients, presenting, on average, in their 70s; about equal numbers of men and women develop these tumors. Although initial reports suggested that these might be indolent tumors, subsequent experience has shown that they have a propensity for local recurrence locally and metastasis, both to regional lymph nodes and to distant sites (including lung and liver). Some investigators have reported a Management of Temporal Bone Malignancy 27 Pathology of Temporal Bone Malignancy mortality rate slightly above 50% for Merkel-cell carcinomas, which is higher than for melanomas (Litofsky et al., 1998). The designation of these neoplasms as Merkel-cell tumors indicates the supposed derivation of these lesions from cutaneous neuroendocrine cells (the Merkel cells). Pathological diagnosis can be complicated by the resemblance of this lesion to both lymphoma and metastatic small-cell carcinoma of pulmonary origin. Immunohistochemical analysis can distinguish between lymphoma and Merkel-cell tumor. (Lehrer et al., 2004). Figure 10: Merkel-cell carcinoma of the antitragus in a 72-year-old man. Tumor cells are round, undifferentiated, and arranged in sheets and cords. Despite superficial location, the tumor has a propensity for spreading to regional lymph nodes and to visceral sites (including lung and liver) (Devaney et al., 2005). Adenexal carcinoma of the ear The mechanism by which the tumor develops is not clearly understood, there are four suspected etiopathogenetic hypotheses: those originating from the seromucinous glands because of functional alterations of the mucosal epithelium, those caused by chronic irritation that causes squamous metaplasia of the mucosa, seromucinous and minor salivary glands implanted in the ear during Management of Temporal Bone Malignancy 28 Pathology of Temporal Bone Malignancy embryogenesis, and finally those caused by secondary invasion of a tumor located in an adjacent primary site (Soh et al., 1996). The two most common malignant glandular neoplasms of the external ear are seromucinous adenocarcinoma and adenoid cystic carcinoma (Mansour et al., 1992). Seromucinous adenocarcinomas arise in adults, with patients presenting on average in their 50s. Although in some cases a deceptively bland appearance on light microscopy suggests that these are benign tumors, seromucinous adenocarcinomas are stubbornly persistent lesions, with a local recurrence approaching 50%. Although these are locally aggressive tumors, they only rarely metastasize to regional lymph nodes or the lungs (Tzagaroulakis et al., 2003). The neoplasm possesses a glandular structure with evidence of apocrine differentiation, but the glands show loss of a myoepithelial layer and the cells are markedly atypical with increased mitotic activity (Lassaletta et al., 2003). The average age at diagnosis of an adenoid cystic carcinoma falls somewhere in the patient’s 50s; occurrence in women predominates over that in men by a ratio of two to one. Many adenoid cystic carcinomas are painful lesions. In common with some seromucinous adenocarcinomas of the external ear, most adenoid cystic carcinomas of the external ear have a bland cytological appearance on light microscopy; this appearance belies their aggressive character when their behavior is tracked over long periods. Although 5-year survival for patients with adenoid cystic carcinomas (arising in all sites) is over 75%, long-term follow-up studies show that 20-year survival is as low as 10% or 15%. It has insidiously Management of Temporal Bone Malignancy 29 Pathology of Temporal Bone Malignancy infiltrative character, which typically shows perineural invasion with far more expansive microscopic extension than had been suggested by physical examination or imaging studies (Kokemueller et al., 2004). Local extension to involve the adjacent parotid gland is common. Nodal metastases are not commonly encountered early in the course of disease. Distant metastatic deposits of adenoid cystic carcinoma commonly develop later in the course of disease. Sites of late metastasis include the lung, lymph nodes, and the skeletal system (Alcedo et al., 2004). Mucoepidermoid carcinomas are malignant tumors that frequently originate in the major and minor salivary glands (Soh et al., 1996). The seromucinous glands are known to be situated in the deep dermis of the external auditory canal. Under histological examination mucoepidermoid carcinoma appear to be composed of scattered solid and cystic mucinous areas. In the solid parts, the cells are arranged in nests, are tubular in structure, and have different characteristics very similar to those of mucous squamous cells, whereas other cells have intermediate histopathological characteristics. According to the percentage of the different cells there is a low-, medium-, or high-grade malignancy (Devaney et al., 2005). In low-grade tumors, there is a higher percentage of mucous cells, and in medium-grade tumors, there is an equal percentage of glandular and epithelial cells. The histological diagnosis of mucoepidermoid carcinoma is often difficult and not always completely reliable. High-grade mucoepidermoid carcinoma are very similar to poorly differentiated squamous carcinoma except for the fact that Management of Temporal Bone Malignancy 30 Pathology of Temporal Bone Malignancy the former has intermediate and mucin-secreting cells, a difference that gives a useful indication in the histological diagnosis. Grossly they appear as solid reddish masses that are variable in shape (usually irregular) and may be located in any part of the external auditory canal (Kim et al., 2001). Figure 11: Glandular tumors (microscopic picture) a. Seromucinous adenocarcinoma. An intact surface epithelium is subtended by an infiltrating "biphasic" neoplastic proliferation separated by dense fibrosis. b. Seromucinous adenocarcinoma demonstrating decapitation secretion in the center gland, while the remarkably atypical cells are seen in an "infiltrative"growth pattern. Note the mitotic figure in the upper right corner. c. Adenoid cystic carcinoma. The overall cribriform ("Swiss-cheese") pattern is seen on both the low power and with the inset. d. Mucoepidermoid carcinoma both the epidermoid and mucous components are clearly shown. (Devaney et al., 2005). Management of Temporal Bone Malignancy 31 Pathology of Temporal Bone Malignancy Sarcomas of the ear Rhabdomyosarcoma is a soft tissue malignant tumor of skeletal muscle origin. It affects children much more common than the adults. Several hypotheses have been set forth concerning the cellular origins of rhabdomyosarcoma tumors. They may originate from either totipotential mesenchymal cells, from immature myoblastic tissue, or from muscles of the middle ear (Ries et al., 1999) . Grossly, the tumor is lobulated and dark red with a haemorrhagic cut surface. Microscopically, rhabdomyosarcoma is composed primarily of small, anaplastic, round and spindle-shaped cells exhibiting hyperchromic nuclei and granular acidophilic cytoplasm. There are four histological subtypes of rhabdomyosarcoma: embryonal, alveolar, botryoid, and pleomorphic. The embryonal subtype remains the most commonly found subtype in the head and neck region; however it is not uncommon to find a mixture of subtypes in individual cases (Parham et al., 2001; Newton et al., 1995). Embryonal rhabdomyosarcoma has high cytologic variability, which represents several stages of skeletal muscle morphogenesis. They may range from highly differentiated neoplasms containing rhabdomyoblasts with large amounts of eosinophilic cytoplasm and cross striations similar to that of poorly differentiated tumor cells. Desmin and muscle specific actin are the typical stains used to identify rhabdomyosarcoma ( Sbeity et al., 2007). Immunohistochemistry remains the current ancillary method of choice in the pathological evaluation of small blue round-cell tumors. In at least 20% of cases of rhabdomyosarcoma, it is considered an essential factor in the final and/or Management of Temporal Bone Malignancy 32 Pathology of Temporal Bone Malignancy differential diagnosis of the malignancy. The newer immune-stains (antimyogenin, MyoD1) generated against intranuclear myogenic transcription factors offer pathologists the best hope for improving the sensitivity and specificity of rhabdomyosarcoma diagnosis ( Morotti et al., 2006). Figure 12: Embryonal rhabdomyosarcoma: undifferentiated primitive cells in a myxoid background. Red cells are differentiating rhabdomyoblasts with one mature cell (arrow) (Sbeity et al., 2007). Chondrosarcoma of the temporal bone is an uncommon neoplasm. It is a malignant tumor of cartilage forming tissues, and can be divided into two major types based on microscopic criteria; conventional chondrosarcoma and chondrosarcoma variants. The latter type is further divided into; clear cell, myxoid, and mesenchymal subtypes (Raghu et al., 2004). Sites of origin within the temporal bone are the petrous apex, mastoid and tympanic portion. Because the embryology of the petrous apex and mastoid involves endochondral development (within cartilage) rather than intramembranous development (within a membrane), chondrosarcomas arise from congenital cell rests within these regions. Poorly differentiated lesions behave more aggressively than better-differentiated tumors (Raghu et al., 2004). Management of Temporal Bone Malignancy 33 Pathology of Temporal Bone Malignancy Figure 13: Chondrosarcoma (A) Histological findings: small cells and a few chondrocytes can be seen embedded in a myxoid area. (B) High-power view showing some binucleated cells (arrows) (Yagisawa et al., 2007). Cutaneous angiosarcoma is a rare form of sarcoma, of which about half are found in the head and neck area. They present as red–purple macular eruptions that might be mistaken for bruising, or as nodular lesions. They are ill defined, and their margins are therefore difficult to assess. Male to female ratio is 2: 1. Children are diagnosed with angiosarcomas occasionally, but the average age at presentation is about 50 years (Pawlik et al., 2003). Angiosarcomas are very aggressive lesions. Distant spread to lymph nodes, the lungs, and the liver commonly develops in these patients. The vague presentation can delay clinical recognition of an angiosarcoma. On examination, even skilled pathologists sometimes have difficulty in discerning the presence or absence of angiosarcoma in biopsy samples of surgical margins. Although some Management of Temporal Bone Malignancy 34 Pathology of Temporal Bone Malignancy angiosarcomas are well differentiated on light microscopy (and thus are recognizable as vascular in nature), other angiosarcomas are more difficult to identify as vascular. Immunohistochemical studies with antibodies such as (CD34, CD31, Fli-1, LYVE-1, and FKBP12) can help resolve diagnostic dilemmas in the diagnosis of such poorly differentiating tumors (Budd, 2002). Before the AIDS epidemic, Kaposi’s sarcoma of the ear was a curiosity occasionally encountered as a minor element of systemic disease, but not in itself a source of substantial disease burden (Babuccu et al., 2003). The AIDS epidemic has, however, changed this situation, and auricular Kaposi’s sarcoma lesions are now encountered regularly. They can even be the presenting sign of the underlying immunodeficiency. Overall, Kaposi’s sarcoma is the most commonly encountered neoplasm in patients with AIDS. Four clinical groupings of Kaposi’s sarcoma are now recognized: chronic (classic, Mediterranean); lymphadenopathic (African); transplantation-associated; and AIDS-related (epidemic). Discovery of the association of Kaposi’s sarcoma with infection with human herpes virus 8 suggests an aetiological role for this virus in this neoplasm. As is the case with some angiosarcomas, the light microscopic appearance of Kaposi’s sarcoma (particularly early lesions) can be reminiscent of several other lesions, ranging from a non-specific reactive process to fibrosarcoma. Immunohistochemical studies with antibodies such as Fli-1, LYVE-1, D2-40, and human-herpesvirus-8-latent nuclear antigen 1 might help unravel the nature of perplexing cases. Kaposi’s sarcoma lesions present as red–purple or brown–red plaques or as nodules of the external ear (Delbrouck et al., 1998). Management of Temporal Bone Malignancy 35 Pathology of Temporal Bone Malignancy Figure 14: Kaposi’s sarcoma of a 23-year-old man with AIDS; The light-microscopic pattern is dominated by proliferation of uniform spindle cells arranged in fascicles, with many interspersed erythrocytes (Devaney et al., 2005). Endolymphatic sac tumor Endolymphatic sac tumor is a slow-growing, locally aggressive neoplasm that originates from the epithelium of the endolymphatic sac and duct. It is a recently recognized neurotologic disease entity characterized by the presence of a destructive papillary cystic adenomatous tumor of the temporal bone. Endolymphatic sac tumors are known to occur more frequently in patients with Von Hippel Lindau disease but these tumors also appear sporadically in patients who do not have that disease (Wada et al., 2006). The ratio of endolymphatic sac tumors have occurred sporadically in patients who do not have Von Hippel Lindau disease compared with patients who do is (103 versus 46). Much information that has been learned recently regarding the genesis of these lesions has been via an understanding of the genetics and molecular biology that result from a mutation in the Von Hippel Lindau tumor suppressor gene. Von Hippel Lindau disease is an autosomal dominant multisystemic disorder characterized by cerebellar hemangioblastomas, retinal angiomas, and renal cysts, clear cell renal carcinomas, and other visceral tumors. Von Hippel Lindau disease has a prevalence of 1 in 39,000 people. The Von Management of Temporal Bone Malignancy 36 Pathology of Temporal Bone Malignancy Hippel Lindau gene product is a tumor suppressor that when lost or mutated results in a loss of inhibition to cell growth and can lead to neoplasms such as endolymphatic sac tumor. The Von Hippel Lindau gene product protein is important in the regulation of hypoxia inducible factor–1a, which controls angiogenesis and cell metabolism (Bambakidis et al., 2004; Jensen et al., 2004). The growth of endolymphatic sac tumor seems to advance slowly, over the course of years. As the tumor grows, it takes on the appearance of an infiltrative, poorly circumscribed neoplasm composed of cuboidal to low-columnar epithelial cells disposed in a fibrous stroma and arranged either in papillary patterns or cystic spaces that contain protein like material resembling thyroid follicles. Before recognition of the endolymphatic sac tumor entity, the finding of these lesions in the temporal bone and cerebellopontine angle was thought by some to be the result of ectopic choroid plexus papillomas because of the similar appearance of aggressive papillary tumors (later believed to be endolymphatic sac tumors) of the temporal bone and tumors of the choroids plexus. Nearly all endolymphatic sac tumor express cytokeratin, vimentin, and epithelial membrane antigen, and most stain positive for S-100 and neuron-specific enolase (Lonser et al., 2004; Kim et al., 2005). Management of Temporal Bone Malignancy 37 Pathology of Temporal Bone Malignancy Figure 15: Histopathologic examination of endolymphatic sac tumor revealed papillar pattern and scattered follicular structures (Yilmaz et al., 2008). Multiple myeloma, and plasmacytoma of the middle and inner ear Haemopoietic lesions, such as lymphoma, multiple myeloma, and plasmacytoma, are rare lesions of the middle and inner ear. Most affected patients are adults, although occasional cases in children have been described (Lang et al., 2003). Plasmacytoma is a rare clinical entity, arising from malignant proliferation of B-cell line, and belongs to non-Hodgkin lymphomas. It derives as a clone of malignant plasma cells. The malignancies considered as plasma cell tumors are extramedullary plasmacytoma, solitary plasmacytoma of the bone, multifocal form of multiple myeloma, multiple myeloma and plasmablastic sarcoma (Dimopoulos et al., 2002). Extramedullary plasmacytomas are rare tumors, encompassing only 4% of all plasma cell malignancies. According to the origin of neoplastic cells, the solitary plasmacytomas are subdivided into solitary bone and extramedullary plasmacytoma. The solitary bone plasmacytoma derives from bone marrow and is Management of Temporal Bone Malignancy 38 Pathology of Temporal Bone Malignancy characterized by bone erosion, whereas the extramedullary one arises in submucosal layer of tissues, without bone involvement (Liebross et al., 1999). Plasmacytomas of the temporal bone are structurally no different than those that occur in other sites. They are constituted by uniform sheets of plasma cells supported by a sparse matrix. Typically, these plasma cells are either poorly or well differentiated, but occasionally a mixed population of small, mature plasma cells and large, immature, multinucleated plasmacytoid cells is present. Amyloid deposits may occasionally be noted. Immunoperoxidase staining shows a monoclonal population of plasma cells, differentiating plasmacytoma from other neoplastic processes. The absence of inflammatory cells distinguishes plasmacytoma from reactive processes such as plasma cell granuloma (Panosian et al., 1994). Figure 16: Plasma cell tumor A. Submucosal solid lymph plasma cells and focal infiltrations of neoplastic plasma cells (hematoxylin-eosin stain). B. Solid summations of neoplastic plasma cells (hematoxylin-eosin stain) (Markou et al., 2009). Management of Temporal Bone Malignancy 39 Pathology of Temporal Bone Malignancy The first essential approach of the differential diagnosis of the Extramedullary plasmacytomas is the exclusion of other plasma cell dyscrasias and especially of dissemination of the disease into multiple myeloma. This systematic examination requires complete blood count with white cell differential, erythrocyte sedimentation rate, serum calcium, phosphorous, blood urea nitrogen, creatinine, serum and urine protein electrophoresis, bone marrow biopsy, chest radiograph, and a radiographic skeletal survey (Markou et al., 2009). Lymphoma of the temporal bone Although lymphomas account for the largest number of nonepithelial malignancies of the head and neck, these lymphoproliferative neoplasms seldom present in the temporal bone area. The temporal bone lymphomas generally present either as metastatic focus from distant primaries or encroachment from contiguous locations. Sporadic cases of primary extranodal lymphoproliferative malignancies originating in the temporal bone area have been reported; potential sites of origin include the middle ear mastoid internal auditory canal and external auditory canal (Fish et al., 2002). Lymphomas typically present as solid, malignant neoplasms that arise from lymphocytes and their respective precursor cells. These malignancies are generally grouped into one of two major categories: Hodgkin disease and non- Hodgkin's lymphoma (Wanamaker et al., 1997). Extranodal involvement although rare in Hodgkin's disease may be present in as many as 30% of patients with non-Hodgkin's lymphoma. Although Management of Temporal Bone Malignancy 40 Pathology of Temporal Bone Malignancy uncommon, a number of cases of temporal bone lymphomas have been reported, in most of them the lymphoma was metastatic (Nathu et al., 1999). Metastatic carcinoma of temporal bone Neoplasms which originate from sites other than the structures of the ear i.e. external auditory canal, middle ear and temporal bone may metastasize via blood or lymphatic channels from non-contiguous sites or spread directly from a contiguous site by invasion of surrounding tissues or extension through existing channels (Miro Castillo et al., 2000). Metastasis through direct extension into the temporal bone occurs from the upper aero-digestive tract via the eustachian tube and middle ear, and from the posterior fossa of the skull via the internal auditory canal. Invasion of bone and soft tissue with extension into the base of the skull, external auditory canal, middle ear and mastoid occurs with paragangliomas and malignancies of the parotid gland (Gloria-Cruz et al., 2000). Breast is by far the most common malignancy metastasizing to the temporal bone, followed by lung/bronchus, prostate, melanoma and thyroid. Blood borne metastases tend to localize to the petrous ridge and mastoid and are usually bilateral, multiple and associated with metastases to other bones (Nelson et al., 1991). Management of Temporal Bone Malignancy 41 Pathology of Temporal Bone Malignancy Patterns of Spread The local extent of primary disease at presentation is the most important determinant of survival (Moffat et al., 2000). Tumors of the temporal bone can erode directly through bone or along preformed vascular and neural pathways. Anterior spread from the external auditory canal to the temporomandibular joint, parotid gland, or infratemporal fossa occurs directly through the thin bone of the external auditory canal, the petrosquamous suture, a patent foramen of Huschke or the fissures of Santorini in the cartilaginous external auditory canal. Medial spread through the tympanic membrane or posteriorly into the mastoid allows access to the entire air cell system of the temporal bone to expose the otic capsule, posterior fossa dura, sigmoid sinus, eustachian tube, and carotid artery (Pensak et al., 1996). Inferior extension can involve the jugular foramen and upper neck compartments. Superior spread erodes the tegmen tympani with potential involvement of the dura and temporal lobe. Large tumors can spread along all pathways (Pensak et al., 1994). Management of Temporal Bone Malignancy 42 Pathology of Temporal Bone Malignancy Figure 17: Coronal anatomy of pathways of spread of primary cancer of the external auditory canal. Cancer can spread (1) anteriorly through the cartilaginous canal into the parotid gland, (2) through the concha into the postauricular sulcus, (3) through the tympanic membrane into the middle ear, (4) posteriorly into the mastoid, (5) into the anterior mesotympanum to the carotid artery and Eustachian tube, (6) into the inner ear through the round window or otic capsule, (7) along the extratemporal facial nerve into the infratemporal fossa, and (8) inferomedially into the jugular fossa, carotid artery and lower cranial nerves. The involvement of upper deep cervical lymph nodes is very uncommon so routine neck dissection is not recommended. Distant metastases are rare but have been reported in the liver, brain, lung, and bones (Moody et al., 2000). Management of Temporal Bone Malignancy 43 Pathology of Temporal Bone Malignancy Staging Systems Unfortunately, there are no universal staging systems for cancers of the external auditory canal, middle ear, and mastoid. Three current systems are summarized in the following table. Stage T1 T2 T3 T4 Modified Pittsburgh (2000) The Otology Group (2000) Clark/Stell (1991) Tumor limited to the external auditory canal Disease confined to external Tumor limited to site without bony erosion or evidence of soft auditory canal including of origin tissue involvement spread from auricular cancer to canal and confined to it Tumor with limited to external auditory canal Disease spread from external bone erosion (not full thickness) or limited auditory canal to one or any (<0.5 cm) soft tissue involvement combination of the following:Temporomandibular joint Parotid Infratemporal fossa Tumor extending beyond site of origin indicated by facial palsy or radiologic evidence of bone destruction Spread of disease from Tumor eroding the osseous external auditory external auditory canal to one canal (full thickness) with limited (<0.5 cm) or any combination of the soft tissue involvement, or tumor involving following: Middle ear Mastoid the middle ear or mastoid Facial nerve and fallopian canal Involvement of parotid gland, temporomandibular joint, or skin (extracranial spread) Tumor eroding the cochlea, petrous apex, medial wall of the middle ear, carotid canal, jugular foramen, or dura, or with extensive soft tissue involvement (>0.5 cm), such as involvement of TMJ or styloid process, or evidence of facial paresis Spread of disease to any one Involvement of dura of the following: or skull base (intracranial spread) Dura, Jugular bulb, sigmoid sinus, Carotid artery or Petrous apex (Barrs, 2001) Management of Temporal Bone Malignancy 44 Pathology of Temporal Bone Malignancy According to Modified Pittsburgh (2000) staging system proposed for the external auditory canal and middle ear N-status; Involvement of lymph node is a poor prognostic finding and automatically places the patient in an advanced stage (i.e., Stage III [T1N1] or Stage IV [T2, T3, T4, N1] disease). M-status; Distant metastasis indicates a very poor prognosis and immediately places the patient in the stage IV category. In the absence of metastatic lymph nodes or distant metastases, T-status defines the overall clinical stage of the patient (Barrs, 2001). Management of Temporal Bone Malignancy 45 Clinical Assessment of Temporal Bone Malignancy Clinical Assessment of Temporal Bone Malignancy Unfortunately, the diagnosis of temporal bone malignancy is seldom made early. The unique anatomy of the temporal bone contributes to this fact. The majority of cancers of the ear have involved bone by the time a diagnosis is made. Carcinomas of the external and middle ear appear to occur mainly in elder people, and the males seem to be more predisposed. The mean age was reported to be over 60 years in some studies. However auricular carcinomas appear in much elder patients (Moody et al., 2000; Pfreundner et al., 1999). The age incidence changes in other types of tumors as in sarcomas specially rhabdomyosarcoma. It is not a tumor of adults; most rhabdomyosarcomas of the ear develop in children. The average age at diagnosis is about 4 years; adolescents or young adults are affected less commonly. So when one encounters the symptoms and clinical findings suggestive of cancer in the pediatric age group, the possibility of embryonal rhabdomyosarcoma should be considered. Sarcomas here are generally considered to be more frequent than carcinoma in the pediatric age group. Needless to say, biopsy is the modality on which we depend for conclusive diagnosis (Durve et al., 2004; Hawkins et al., 2001). Also in the case of endolymphatic sac tumor that arises in association with Von Hippel–Lindau disease occurs in young age group. While if it is not associated with Von Hippel–Lindau disease, it occurs in older age groups (Bambakidis et al., 2004). Management of Temporal Bone Malignancy 46 Clinical Assessment of Temporal Bone Malignancy The most frequent symptoms associated with malignant disease of the temporal bone are chronic otorrhea, hearing loss and pain. Later symptoms are bleeding, vertigo, facial paralysis, and the presence of a mass protruding from the external canal. These symptoms depend upon several factors such as the presence of infection, the actual site of origin, the activity of the tumor, and the size of the tumor (Leonetti et al., 1996). Chronic otorrhea is such a common finding associated with middle ear malignancy that it is suspected to be one of the etiologic factors. On the other hand, it is extremely rare to find cancer of this region without evidence of infection and with an intact tympanic membrane. Figure 18: Photograph of the left ear shows a tumor extruding from the External auditory canal (Takahashi et al., 2002) Multiple fibrous polyps are not infrequently seen. The presence of highly vascular granulomatous tissue must be viewed with suspicion. Its frequent appearance in benign chronic ears may lower one's guard in diagnosing malignant disease. So, many patients with temporal bone malignancy their first presentation is long history of chronic ear not responsive to medical treatment. For that it is recommended to take biopsy from any granulomatous tissue that does not Management of Temporal Bone Malignancy 47 Clinical Assessment of Temporal Bone Malignancy respond to a reasonable course of local and systemic therapy (Aarena & keen 1988) Carcinoma of the temporal bone can present as bloody otorrhea without history of chronic ear. Also the patient may mislead necrotic tissue or tumor mass in the ear canal as ear wax (Moody et al., 2000). There are certain symptoms and signs suggestive of local extension and spread of the tumor; as uncontrollable pain which may radiate to the face. The development of facial nerve paralysis due to involvement of facial nerve in its bony canal in the medial wall of the middle ear. Also the presence of severe conductive hearing loss, unilateral sensorineural hearing loss, otitis media, vertigo, taste dysfunction, may indicate invasion into the middle ear, eustachian tube, and otic capsule. The presence of Horner's syndrome, transient ischemic attacks, or syncope may indicate involvement of the internal carotid artery (ICA). The presence of seizures, dysphasia, and other cognitive deficits warrant investigation for intracranial spread of tumor. There may be tenderness in the region of the mastoid due to infiltration of cell system of the mastoid bone and trismus from pterygoid muscle involvement. Swelling in the parotid region due to spread to the parotid gland. A late feature is the jugular foramen syndrome producing paralysis of the tongue, palate and larynx (Yeung et al., 2002). However, the patient should be examined carefully for physical evidence of a mass in the neck, soft palate and post auricular region. An audiogram is obtained to establish the type and degree of hearing loss. The status of the hearing is important because preservation of hearing is possible only if lateral resection of the temporal bone is performed (Hirsch B. et al., 2008). Management of Temporal Bone Malignancy 48 Radiological Diagnosis of Temporal Bone Malignancy Radiological Diagnosis of Temporal Bone Malignancy Computed Tomography (CT) of The Temporal Bone CT scanning became widely used in the 1970s. Because of the exquisite bony detail it can provide, it is beneficial for assessing temporal bone and skull base lesions. The most recent technologic advance is the advent of multidetector (multislice) scanners (Butler et al., 1999). Standard Spiral CT CT scanning of the skull base should be tailored for the anatomic region under consideration. Spiral (helical) CT scanning is rapidly replacing conventional dynamic CT (slice-by-slice acquisition) in most medical centers. Spiral CT, which involves the continuous rotation of the x-ray tube and detector row as the patient translates through the scanning gantry, permits rapid scanning of large volumes of tissues and usually reduces the amount of needed intravenous contrast material, eliminates much of the motion artifact seen with slower scans, and allows multiplanar and threedimensional (3D) reconstructions. Moreover, multirow detector technology, which entails rotating the x-ray tube while simultaneously employing multiple parallel detector arrays rather than a single detector row, has further advanced spiral CT by reducing scan time and greatly increasing anatomic coverage. Debilitated, elderly, or arthritic patients may require scanning in the supine position; however, reformatted coronal images are usually easily derived from the axially acquired data. With the widespread application of spiral technology and filmless picture archiving and communications systems (PACS), reformatted coronal and sagittal images may be obtained at the workstation, obviating the need to scan the patient in multiple planes. General surveys typically cover the base of the skull to the clavicles with 4 Management of Temporal Bone Malignancy 49 Radiological Diagnosis of Temporal Bone Malignancy or 5 mm thick slices. The use of intravenous contrast is recommended. For special regions of interest, patients may be scanned with additionally acquired 2 mm slices and a higher zoom factor, or with newer scanners, the same information can be obtained using reconstructed spiral data (Spreer et al., 1995). Multidetector CT The current generation of 64-slice scanners allows for rapid volumetric image acquisition with resolution in the range of 0.3 to 0.6 mm. Because the data are acquired for an entire volume in a single pass, there is no need for performing scans in multiple planes (axial, direct coronal, and sagittal). The volumetric data can be reformatted rapidly in any desired plane and without loss of resolution, which is a tremendous improvement that allows visualization of the anatomy in novel ways. Another advantage is that the current scanning protocols require approximately 5 to 10 seconds for image acquisition. The incredibly rapid acquisition time greatly reduces motion artifact and often the need for sedation in infants or young children, which reduces not only the risk of the procedure but also the cost to the health care system (Leblanc et al., 1999). Figure 19: Sensation 64 scanner equipped with 32 detectors and two sources. Images through the skull base can be obtained in less than 10 seconds. The volumetric acquisition allows for reconstruction of the data in any plane without loss of resolution (Driscoll and Lane 2007) Management of Temporal Bone Malignancy 50 Radiological Diagnosis of Temporal Bone Malignancy CT angiography CT angiography can be performed on multidetector CT scanners as a noninvasive means to obtain information concerning the skull base arterial anatomy. The technique can be useful for identifying an aberrant carotid artery or assessing vascular malformations or the interface between tumors and arterial vasculature. Angiography should be performed in all cases in which the carotid artery is at risk. When carotid resection is anticipated, cerebral blood flow analysis should be used to determine resectability and the need for revascularization. Consideration should also be given to embolization when intraoperative hemorrhage is a concern. Contrast is given during image acquisition and the image viewing software is used to subtract out bone and other structures to allow isolated views of the arteries. The high quality of these images often obviates the need for a formal angiogram (Vrtiska et al., 2005) There are important points considering each part in studying of the CT of temporal bone. External Ear The entire external auditory canal can be seen on axial images at and just below the level of the temporo–mandibular joint where it is S-shaped. The tympanic membrane is stretching superiorly from the scutum down to the tympanic annulus. The scutum is normally thin and sharply edged and is an important bony landmark. The scutum, the tympanic membrane and the tympanic annulus are best demonstrated on coronal images (Butler et al., 1999). Management of Temporal Bone Malignancy 51 Radiological Diagnosis of Temporal Bone Malignancy Figure 20: Axial CT image at the level of the left temporomandibular joint demonstrating the S-shape and the junction of the cartilaginous and bony portions of the external auditory canal. 1-External auditory canal (EAC), 2-cartilaginous portion of EAC, 3-bony portion of EAC, 4-pinna, 5- Tympanic membrane (Ahuja et al., 2003). Figure 21: Coronal CT image at the mid bony portion of the left external auditory canal. 1-Pars flaccida, 2-pars tensa, 3-tympanic membrane, 4-scutum, 5-tympanic annulus, 6-epitympanum, 7-mesotympanum, 8-hypotympanum, 9-tympanic segment of facial nerve (Ahuja et al., 2003). Middle Ear The middle ear cavity is divided into three compartments in the coronal plane. A line drawn from the lower edge of the scutum to the tympanic portion of the facial nerve divides the superior compartment, the epitympanum (attic), from the middle compartment, the mesotympanum (tympanic cavity proper). A line drawn parallel to the floor of the external auditory canal further divides the mesotympanum from the inferior compartment, the hypotympanum. (Butler et al., 1999). Management of Temporal Bone Malignancy 52 Radiological Diagnosis of Temporal Bone Malignancy The epitympanum contains the head of the malleus, the malleo– incudal articulation and the body and short process of the incus, which are best demonstrated on axial images at about the level of the vestibule. The roof of the epitympanum forms an important bony landmark, the tegmen tympani. The tegmen serves as a barrier between the middle ear cavity and the middle cranial fossa. The integrity of the tegmen tympani is best evaluated on coronal images. The space situated between the scutum and pars flaccida laterally and the neck of the malleus medially is known as the Prussak’s space or the lateral epitympanic recess (Curtin et al., 1996; Swartz et al., 1998). Posteriorly the epitympanum opens into the mastoid antrum via the aditus ad antrum; this opening is well demonstrated on both the axial and coronal images. The medial wall of the epitympanum is the cortex overlying the lateral semicircular canal. The tympanic portion of the facial nerve runs posterolaterally inferior to the lateral semicircular canal. In this area the bony floor of the facial nerve canal is very thin and may not be visualized on coronal CT images. The tympanic segment of the facial nerve can also be identified on the axial images running from the anterior genu posterolaterally just below the lateral semicircular canal to the posterior genu. The mesotympanum contains the rest of the ossicular chain. On coronal images the long process of incus is vertically oriented parallel to the malleus manubrium, continuing as the rounded lenticular process with the ―hockey stick‖ appearance and with the facet to articulate with the head of the stapes. The stapes hub and crura are best demonstrated on axial images at the level of the oval window. The floor of the hypotympanum is a thin Management of Temporal Bone Malignancy 53 Radiological Diagnosis of Temporal Bone Malignancy plate of bone separating the middle ear cavity from the jugular bulb, and in a case of dehiscence may allow a high-riding jugular bulb to herniate into the hypotympanum (Swartz et al., 1998). Inner Ear The inner ear includes the membranous labyrinth within the bony labyrinth (otic capsule). The membranous labyrinth contains endolymph and is surrounded by perilymph, which together appear as low attenuation on CT and high fluid signal on T2- weighted images but cannot be independently demonstrated by imaging. The bony labyrinth consists of the cochlea, the vestibule, the semicircular canals and the cochlear and vestibular aqueducts (Leblanc et al., 1999). There are three semicircular canals, namely the superior (anterior), lateral (horizontal) and posterior semicircular canals. They are perpendicular to each other. The plane of the posterior semicircular canal is parallel to the petrous ridge while that of the superior semicircular canal is perpendicular to it although both are in the vertical plane. The vestibule is separated from the middle ear cavity by the oval window niche. The superior semicircular canal forms a bony ridge at the roof of the petrous bone called the arcuate eminence giving a landmark to the surgeon entering through the middle cranial fossa (Swartz et al., 1998). Management of Temporal Bone Malignancy 54 Radiological Diagnosis of Temporal Bone Malignancy The following are consecutive axial CT images of the right middle and inner ear from caudal to cephalic: Figure 22: 1-Manubrium of malleus, 2-basal turn of cochlea, 3-cochlear aqueduct, 4-tensor tympani muscle, 5-tensor tympani tendon, 6-neck of malleus, 7-lenticular process of incus, 8-incudostapedial articulation, 9-hub and posterior crus of stapes, 10-facial nerve, 11-pyramidal eminence, 12-sinus tympani, 13-bony margin inferior to the oval window. PT—protympanum, MT— mesotympanum, PosT—posterior tympanum (Ahuja et al., 2003). Figure 23: 14-vertical portion of the basilar turn of cochlea, 15-apical turn of cochlea, 16-tympanic portion of the facial nerve canal, 17-head of malleus, 18-body of incus, 19-short process of incus, 20-lateral semicircular canal, 21-vestibule, 22-internal auditory canal, 23-posterior semicircular canal, 24-vestibular aqueduct (Ahuja et al., 2003). Management of Temporal Bone Malignancy 55 Radiological Diagnosis of Temporal Bone Malignancy Figure 24: 25-malleoincudal articulation, 26-aditus ad antrum, 27-anterior genu of the facial nerve, 28-labyrinthine portion of the facial nerve canal, 29-superior semicircular canal (Ahuja et al., 2003).. In general, high resolution CT scan gives good accuracy in determining the presence of the tumor and its extensions regarding the presence of bone invasion or not. However distinguishing mucosal thickening from tumor on CT imaging was more difficult. MRI scans were more sensitive in this respect (Driscoll and Lane 2007). High resolution CT scan is rapidly becoming the procedure of choice for evaluation of temporal bone, nasopharynx, infratemporal fossa and base of skull. Making it ideally suited for evaluation of primary tumors of the ear which can involve any of these areas. Intravenous contrast material is helpful in identifying tumor extension beyond the confines of the temporal bone especially in the parotid gland, infratemporal, fossa and dura of the middle or the posterior cranial fossa (Shaffer et al., 1980). So, CT is helpful in the staging, management and prognosis of temporal bone malignancies (Goodwin and Jesse, 1980). Management of Temporal Bone Malignancy 56 Radiological Diagnosis of Temporal Bone Malignancy In the following, shows the usage of CT in diagnosing temporal bone lesions: Figure 25: Oblique coronal CT scan shows an extensive destructive lesion of the left temporal bone with mottled calcification (Takahashia, 2002). Figure 26: An endolymphatic sac tumor in a 15-year-old patient with Von HippelLindau disease who first developed facial paralysis 1year before presentation, severe vertigo and sudden sensorineural deafness on the right side. CT scan reveals the tumor extending superiorly with destruction of the right lateral and superior semicircular canals. No evidence of contralateral endolymphatic sac tumor (Megerian 2007). Management of Temporal Bone Malignancy & Semaan, 57 Radiological Diagnosis of Temporal Bone Malignancy Magnetic Resonance Imaging (MRI) of The Temporal Bone MRI has been the most important development in the assessment of skull base lesions. The examination is performed in the axial, coronal, and sagittal planes with 3-mm sections. All signal intensities (T1- and T2weighted, and proton density images) are applied for evaluation of the anatomy (T1-weighted images) and lesion characterization (T2-weighted images). Also MRI is important in defining intracranial tumor extension and differentiation of cystic from solid lesions. Magnetic resonance angiography (MRA) defines the vascular anatomy in relation to tumors and cysts and may also depict hypervascularity of lesions (Driscoll and Lane 2007). Soft tissue discrimination is best achieved with MRI. Tumor can usually be separated from muscle and fat using T1- weighted images, proton density images and T2-weighted images. If tumor invades fatty planes, the normal high signal intensity of these planes is obliterated by the more intermediate signal intensity of the tumor. This is relevant to the evaluation of the pterygoid fossa, parapharyngeal space at the base of skull and exit foramina of the cranial nerves (foramen rotundum, ovale, spinosum, and stylomastoid foramen), which all contain fatty tissue. Perineural tumor spread will obliterate the fat at the extra cranial opening of the foramina (Curtin et al., 1985). With the introduction of gadolinium, lesion detection and conspicuity have been increased. Recently, fat suppression techniques with contrast enhancement have been used to define tumor extent optimally in the region below the skull base (Laine et al., 1990; Tien, 1992). Management of Temporal Bone Malignancy 58 Radiological Diagnosis of Temporal Bone Malignancy Magnet strength in MRI Currently, the most widely available magnet strength is 1.5 T, with many institutions having one or more 3-T magnets. Higher strength magnets offer several potential advantages, including improved resolution, increased signal-to-noise ratio, and faster scanning times. Higher strength magnets also can create more problems with certain artifacts, so a stronger magnet does not always yield better images. Higher strength magnets also have the potential to cause tissue injury caused by heating (Driscoll and Lane, 2007). Figure 27: An MRI scanner. Large patients and patients with claustrophobia may not be able to be accommodated or tolerate the narrow bore of high-strength MRI scanner (Driscoll and Lane, 2007). Management of Temporal Bone Malignancy 59 Radiological Diagnosis of Temporal Bone Malignancy Here are MRI images demonstrating lesions that could affect the temporal bone: Figure 28: Magnetic resonance imaging of the internal acoustic canal revealed the following characteristics: The lesion originated from the petrous part of the left temporal bone, obliterated the pontomedullar and pontocerebellar cistern, pressed the brainstem and left cerebellar hemisphere but did not cause apparent effects of deviation, entered below the temporal lobe, was sometimes cystic and lobulated, demonstrated homogenous postgadolinium contrast, occupied the entire mastoid and middle ear, narrowed the external ear canal from the upper side, and disturbed the cortex integrity in a 2 cm by 3 cm field at the mastoid cortex superior section. The mass extended to the left jugular foramen. There was a signal void loss that could have been associated with the absence of flow in the left internal jugular vein (Yilmaz et al., 2008). Management of Temporal Bone Malignancy 60 Radiological Diagnosis of Temporal Bone Malignancy Figure 29: Rhabdomyosarcoma in a 6-year-old girl presenting with deafness on the right side and sudden onset of facial paralysis. (A) Unenhanced spin echo (SE) T1-weighted image. The hypointense fluid signal in the IAC on the right side is replaced by soft tissues with an isointensity to brain tissue (arrowheads). The fat signal in the petrous apex on the right side is replaced by soft tissues (large arrow). Compare with the normal fatty marrow signal in the left petrous apex. There seems to be extension in the anterior side of the petrous bone, probably along the course of the facial nerve (small arrows). The middle ear signal void is replaced by an isointense signal (B) Postgadolinium SE T1-weighted image. There is strong enhancement of the mass lesion in the IAC and cerebellopontine angle (arrowheads). There is also enhancement of the mass lesion in the petrous apex (large arrow) and in the anterior part of the petrous bone, probably in the extension along the facial nerve (small arrows). Although the lesion mimics a facial nerve schwannoma, these lesions are considered extremely rare in young children. A middle and inner ear mass lesion in a child should always include rhabdomyosarcoma in the differential diagnosis (De Foer et al., 2009). Management of Temporal Bone Malignancy 61 Radiological Diagnosis of Temporal Bone Malignancy Figure 30: Adenoid cystic carcinoma with perineural spread along the facial nerve in a 35-year-old woman with persistent and painful facial nerve palsy lasting for at least 6 months. (A) Axial T2-weighted MR imaging at the level of the parotid gland shows a slightly hyperintense, heterogeneous, unsharp mass lesion in the left parotid gland (arrows): adenoid cystic carcinoma of the left parotid gland. (B) Axial unenhanced T1weighted MR imaging at the level of the stylomastoid foramen. The right stylomastoid foramen demonstrates normal hyperintense signal attributable to the fat around the facial nerve (large arrow). This fatty signal on the left side has disappeared because of tumoral infiltration along the facial nerve (small arrow) (De Foer et al., 2009). Management of Temporal Bone Malignancy 62 Radiological Diagnosis of Temporal Bone Malignancy Registration and Fusion of CT and MRI of the Temporal Bone CT and MRI of the temporal bone provide complementary information about temporal bone structures and pathologies. CT allows imaging of bony structures, whereas MRI enables imaging of soft tissue structures. So image registration and fusion gains a significant improvement over conventional images in depicting the relationship between bone and soft tissue (Panigrahy et al., 2000). An accurate image registration and fusion could be especially useful in the temporal bone, because here, small soft tissue structures are embedded in the surrounding bone. For example, to assess the facial nerve along its entire course, one has to switch from the direct MR imaging of the nerve in the internal auditory canal (IAC) to the indirect CT imaging of its bony canal, aligning the images mentally for this transition. The same problem occurs when other structures such as the inner ear and IAC and their bony delineation need to be aligned (Hill et al., 1994). So, in the registered images, the facial nerve can be seamlessly followed along its entire course. In malformations, this could improve diagnostic accuracy, because the facial nerve and its canal can be identified more reliably. For tumor surgery within the IAC, accurate surgical planning is necessary. Almost all important surgical landmarks such as the IAC, facial nerve canal, inner ear, vestibular and cochlea aqueduct are all solely displayed in CT and the tumors are mostly solely displayed in MRI. Without registration, the surgeon relies on a rough assessment of the surgical approach by mentally integrating the information of both modalities. Management of Temporal Bone Malignancy 63 Radiological Diagnosis of Temporal Bone Malignancy Registration of CT and MRI allows an assessment of the tumor extent relative to important surgical landmarks that need to be avoided during surgery. Especially the 3D imaging of the tumor together with important surgical landmarks can be beneficial for surgical planning and guiding during surgery. This method allows measurements to be taken within the registered data set to objectively assess whether it is possible to reach the tumor through certain surgical approaches and therefore to assess the feasibility of various surgical approaches (Hans et al., 1999). So co-registration and subsequent 3 dimensional visualization were evaluated for high-resolution CT and MRI of the temporal bone. Coregistration resulted in highly accurate and feasible multimodality images. We found that registered images are superior to conventional images for delineating the relationship between bony and soft tissue structures of the temporal bone. Excellent applications are the surgical planning for cochlea implantation and tumor surgery of the IAC, which can be further improved by 3D imaging of the structures from either modality together in 1 model. The only trade-off is the time need for the post processing; therefore, it is preferable to do the registration and fusion of the temporal bone in special cases (Ellul et al., 2000). Management of Temporal Bone Malignancy 64 Radiological Diagnosis of Temporal Bone Malignancy Figure 31: Registration and Fusion of CT and MRI of the Temporal Bone (A) Lesion is present in the right internal auditory canal (arrow) in registered and fused CT and MRI of the temporal bone. (B) For surgical planning, the MRI-given tumor (yellow) and critical CT-given surgical landmarks such as the labyrinth (blue) and the facial nerve canal (gray) (C) As well as the bony skull base (white) can be displayed together (Bartling et al., 2005). Management of Temporal Bone Malignancy 65 Surgical Management of Temporal Bone Malignancy Surgical Management of Temporal Bone Malignancy Cancer of the temporal bone is a challenging disease to be treated effectively. Modern management of this disease consists of combined modality therapy, including surgery to remove all evident disease and radiation therapy to treat the margins of resection. The surgical procedure of choice depends on the extent of disease and consists of lateral resection of the temporal bone; subtotal resection of the temporal bone; subtotal resection of the temporal bone with extension to the infratemporal fossa, jugular foramen, or dura; and total resection of the temporal bone, which includes removal of the petrous apex (Hirsch et al., 2008). The management of cancer of the temporal bone was first discussed by Politzer in 1883. Radical mastoidectomy with radiation therapy was previously the recommended treatment, but cure rates were quite low. In 1954, Parsons and Lewis described the technique of en bloc subtotal temporal bone resection. Lederman presented the first large series of patients treated by radiation therapy in 1965 and established the concept of combined therapy at a time when the role of radiation in treating cancer of the temporal bone was not yet well accepted. In 1984, Graham and colleagues reported total en bloc resection of the temporal bone, including the internal carotid artery. Postoperative radiation therapy should encompass the resection margins, residual parotid gland, infratemporal fossa and ipsilateral neck (John et al., 2002) Management of Temporal Bone Malignancy 66 Surgical Management of Temporal Bone Malignancy Figure 32: Types of temporal bone resections Axial (A) and coronal (B) illustrations demonstrating (1) lateral resection of the temporal bone, (2) subtotal resection of the temporal bone, and (3) total resection of the temporal bone. The carotid artery is preserved in this illustration (Hirsch et al., 2008). Management of Temporal Bone Malignancy 67 Surgical Management of Temporal Bone Malignancy Depending on the stage of disease, surgical treatment of cancer arising in the temporal bone is potentially a major undertaking. The risk of morbidity and mortality increases with factors such as advanced age and medical conditions as coronary artery disease, pulmonary disease, diabetes mellitus, and peripheral vascular disease. However, because combined modality therapy that includes major surgery appears to be the only treatment that offers any reasonable chance of control of cancer, there is no absolute medical contraindication to surgical treatment (De Vries et al., 1990). The treatment program depends primarily on the extent of the cancer. Cancer limited to the EAC (T1, T2) is treated by lateral temporal bone resection with superficial parotidectomy and preservation of the facial nerve. Rarely, the cancer may be small, isolated in the lateral cartilaginous aspect of the EAC, and not eroding bone, thereby permitting sleeve resection of the external canal skin, lateral to the tympanic membrane. In practice, sleeve resection is probably not oncologically adequate (Moffat et al., 2005). Cancer that has invaded the middle ear and mastoid cavities (T3) is treated by subtotal temporal bone resection. Total temporal bone resection (sometimes called radical temporal bone resection) is performed when cancer extends to the petrous apex. Cancer extending to the temporomandibular joint, neck, dura, or infratemporal fossa (T4) will require resection of these structures (Moffat et al., 2005). Parotidectomy is routinely performed in conjunction with temporal bone resection. Ideally, the parotid is resected en bloc with the temporal bone. However, for T1 and T2 cancers, superficial parotidectomy is Management of Temporal Bone Malignancy 68 Surgical Management of Temporal Bone Malignancy sufficient. For T3 and T4 cancers and if the facial nerve must be resected, total parotidectomy is performed (Hirsch et al., 2008). Supraomohyoid neck dissection is performed in most cases. The lymphatic drainage of pinna and EAC lesions is not entirely predictable but will often extend to the upper jugular nodal chain. Also, exposure of cervical structures provides safe control of the great vessels, if needed. In a clinically N0 neck, neck dissection can be done as a staging procedure to assist in the decision as whether to proceed with postoperative radiation therapy. The survival benefit provided by elective neck dissection is unclear (Moffat et al., 2005). Neck dissection is commonly carried out at the time of temporal bone resection, which provides good local/regional control but does not seem to affect survival (Moody et al., 2000). The presence of metastatic cancer, especially in the neck, should be detected before therapy. Metastasis to the neck is unusual in cancer of the temporal bone, but a thorough physical examination and CT or MRI with contrast enhancement should detect lymph node involvement. Spread of cancer to the lymph nodes in the superficial lobe of the parotid gland is more common, so the superficial lobe of the parotid gland is usually removed during surgery with preservation of the facial nerve. If the pathology is squamous cell carcinoma, a metastatic evaluation consisting of chest radiography and liver function testing is adequate. In malignant tumors with a high predilection for systemic spread such as melanoma, CT scanning of the chest, abdomen, and pelvis, as well as whole-body bone scanning, should be performed (Myers et al., 2008) . Management of Temporal Bone Malignancy 69 Surgical Management of Temporal Bone Malignancy Preoperative staging determines the scope of the planned procedure and the necessity for a team approach. Neurosurgical participation is appropriate when surgery requires intracranial resection. Similarly, wound closure after tumor removal may necessitate transfer of regional or distant tissue, thus warranting consultation with a reconstructive surgeon. Surgical treatment of cancer of the temporal bone usually requires a long duration of anesthesia and can entail major blood loss and fluid shifts, intracranial manipulation, and postoperative stress, including fluid and electrolyte abnormalities, pulmonary and cardiac stress, coagulation abnormalities, and the possibility of aspiration. The patient's medical status should be optimized before surgery (Hirsch et al., 2008). Incisions vary according to the extent of the tumor. The incision is designed postauricular and either to incorporate the pinna in case when it must be removed or to retract it anteriorly, or superiorly. Then the incision is extended superiorly into the temporal fossa and inferiorly into the neck. When tumor invasion of the conchal cartilage or periauricular skin is suspected, an appropriate skin island is incorporated into the overall design. A blind-sac closure of the EAC helps contain the specimen. The EAC skin is sutured shut to avoid tumor spillage. The outline of the incisions should preserve the blood supply to the remaining auricle. The anterior and posterior skin flaps are elevated. The superficial temporal fat pad is elevated with the anterior skin flap in a subperiosteal plane over the zygomatic arch (Neely, 1982). Management of Temporal Bone Malignancy 70 Surgical Management of Temporal Bone Malignancy Lateral temporal bone resection According to the extent of the disease, lateral temporal bone resection can be classified into four types. Type I resection consists of removal of tympanic bone & EAC lateral to the tympanic membrane. The type II resection consists of the removal of the entire tympanic bone, the tympanic membrane, the incus and the malleus preserving the facial nerve and the inner ear. Type III resections remove, in addition to type II, the distal facial nerve and fallopian canal, the mastoid tip, the styloid process, and the stylomastoid foramen. The type IV resection consists of the removal of only the mastoid tip and the inferior portion of the tympanic bone. The decision to perform a lateral temporal bone resection and the decision as to what type of temporal bone resection to perform is based on the location and extent of the tumor (Medina et al., 1990). A lateral temporal bone resection is considered when a malignant tumor clinically and /or radiographically involves the postauricular sulcus skin, the concha, and the external auditory canal or invading the tympanic bone the mastoid cortex or both but doesn’t invade the middle ear or any pneumatized space in the temporal bone (Medina et al., 1990). After the incision cortical mastoidectomy and exploration of the middle ear is done through an extended facial recess approach any suspected tissues should be removed and must be examined by frozen section. Then the bone lateral to the epitympanum is removed to the level of root of zygoma and temporomandibular joint. The bone lateral to hypotympanum and the facial nerve is also removed in an anterior direction to the temporomandibular joint (Medina et al., 1990). Management of Temporal Bone Malignancy 71 Surgical Management of Temporal Bone Malignancy Then after that we can perform one of the following types of lateral temporal bone resections that can be selected according to the location and extent of the tumor: Type I lateral temporal bone resection (sleeve resection of the EAC) is considered when the tumor originated in the concha or in the periauricular skin but didn’t involve the skin of the EAC grossly, didn’t infiltrate into the parotid, the temporomandibular joint or involved the facial nerve. The tympanic bone is cut circumferentially in a plane lateral to the tympanic membrane the complete circumference of the EAC is cut with a drill into the temporomandibular joint. Frozen section from the entire circumference of medial margin of skin of the EAC and from the capsule of the temporomandibular joint is taken. If proved positive for tumor invasion consider type II lateral temporal bone resection (Medina et al., 1990). Figure 33: lateral temporal bone resection type I. Left, outline of the bone cuts in the EAC. Center, EAC fractured forward (the bone cut is performed just lateral to the tympanic membrane and the facial nerve. Right, remaining structures and defect after removal of the surgical specimen. Type II lateral temporal bone resection this operation is performed when the tumor is originated from the EAC or extended grossly into it from Management of Temporal Bone Malignancy 72 Surgical Management of Temporal Bone Malignancy the pinna or the periauricular skin. After the initial steps described previously were completed, the facial recess is opened, the incus will be disarticulated from the stapes, and the tensor tympani tendon is cut. The fallopian canal is identified, but not opened, from the geniculate ganglion to the stylomastoid foramen, the chorda tympani is cut. The bone about the hypotympanum is removed in a plane medial to the tympanic annulus and just lateral to the jugular foramen and the carotid canal. The removal of the bone is carried up to the glenoid fossa. After completion of this step of the operation, the lateral portion of the temporal bone to be resected was only connected to the rest of the temporal bone by a thin plate of bone between the hypotympanum of the middle ear and the glenoid fossa in the area of the eustachian tube. This will be easily fractured forward by gentle pressure on the bony canal, freeing the surgical specimen (Medina et al., 1990). Figure 34: lateral temporal bone resection type II. Left, outline of the bone cuts in the tympanic bone and potential extension to the neck of the condyle. Center, the tympanic bone with attached tympanic membrane, malleus, and incus has been fractured forward. Right, remaining structures and defect after removal of the surgical specimen. Type III lateral temporal bone resection when the location and extent of the tumor dictated the need to resect the entire tympanic bone, the stylomastoid foramen, and the facial nerve, as in the case of persistent or Management of Temporal Bone Malignancy 73 Surgical Management of Temporal Bone Malignancy recurrent tumors following superficial parotidectomy the bone cuts are performed in a plane medial to the fallopian canal, the stylomastoid foramen, and styloid process, which will be included in the resected specimen. The jugular foramen and the internal carotid artery are the medial limit of the resection (Medina et al., 1990). Figure 35: lateral temporal bone resection type III. Left, outline of the bone cuts the fallopian canal and potential extension to the neck of the condyle. Center, lateral portion of the temporal bone to be resected, including the styloid process, fallopian canal,and facial nerve. Right, remaining structures and surgical defect. Type IV lateral temporal bone resection this type of resection is done when the tumor is adjacent only to the mastoid tip, the inferior aspect of the tympanic bone, or both. The EAC lumen, the tympanic membrane, and the middle ear structures are preserved while the inferior portion of the tympanic bone and the mastoid tip is resected. Depending upon the clinical situation, the facial nerve and the styloid process could be resected or preserved (Medina et al., 1990). Management of Temporal Bone Malignancy 74 Surgical Management of Temporal Bone Malignancy Figure 36: lateral temporal bone resection type IV. Left, outline of the bone cuts through the mastoid tip and inferior portion of the tympanic bone. Center, resected portion of the temporal bone displaced forward. Right, remaining structures and surgical defect. The resection of the lateral portion of the temporal bone could be done in conjunction with a parotidectomy, a partial mandibulectomy or resection of the glenoid fossa and the floor of the middle cranial fossa, depending upon the extent of the tumor (Hirsch et al., 2008). The resulting surgical defect is repaired with a temporalis muscle flap, a split thickness skin graft, or both, whenever possible. Large defects, particularly those in which the dura or the internal carotid artery was exposed, will be repaired with myocutaneous flaps (Medina et al., 1990). The four types of lateral temporal bone resections described here can be used for the surgical treatment of selected malignant tumors of the ear, periauricular skin, and the parotid. Proper use of these techniques requires a methodical preoperative evaluation and a systematic intraoperative assessment of the extent of the tumor. In general the morbidity associated with the lateral temporal bone resections is low (Medina et al., 1990). Management of Temporal Bone Malignancy 75 Surgical Management of Temporal Bone Malignancy Subtotal Temporal bone resection It is indicated in the case of cancer extending medial to the tympanic membrane and invading the middle ear, hypotympanum, otic capsule, facial nerve, or mastoid (Kinney, 1989). The approach for lateral resection of the temporal bone is performed as described previously, with examination of the middle ear through the facial recess and mastoid cavity for cancer. If the cancer is present and the decision is to be subtotal resection we proceed as follows. The temporalis muscle is elevated in a subperiosteal fashion and reflected inferiorly. It must be separated from the lateral pterygoid muscle, and care should be taken not to injure the deep temporal arteries supplying blood to the temporalis muscle (Prasad and Janecka, 2010). A temporal craniotomy is performed, and the intracranial portion of the middle meningeal vessels is coagulated. This maneuver will define an intracranial margin to establish resectability of the tumor mass. If the tumor extends through dura, the dura can be resected free of the temporal lobe. However, extension of the tumor into the temporal lobe makes it inoperable (Sataloff et al., 1988). The facial nerve can be handled differently, depending on tumor invasion of the parotid gland. When the parotid gland is involved, peripheral branches of the facial nerve are identified and then divided. The entire parotid gland is dissected and mobilized posteriorly, while the attachment to the EAC is maintained. When the parotid gland is suspected to be free of tumor, the facial nerve trunk is located in the usual manner at the Management of Temporal Bone Malignancy 76 Surgical Management of Temporal Bone Malignancy tympanomastoid suture and divided. The parotid gland, along with the distal stump of the facial nerve, is dissected free of the EAC and mobilized anteriorly. The ninth cranial nerve, the greater auricular nerve, or cervical cutaneous nerves can be used as cable grafts for facial nerve reconstruction (Hirsch et al., 2008). The jugulodigastric region is explored, and cervical lymph nodes are sent for frozen section pathologic analysis. Regional metastases determine the need for a formal cervical lymphadenectomy (Prasad and Janecka, 2010). Cranial Nerves IX, X, XI, and XII; the internal jugular vein; the external and internal carotid arteries are dissected. The sternocleidomastoid and digastric muscles are detached from their attachment to the mastoid. The masseter is detached from the zygomatic arch, allowing exposure of the zygoma and mandible. Zygomatic and mandibular osteotomies can then be performed (Prasad and Janecka, 2010). The meniscus of the temporomandibular joint is separated from the glenoid fossa. The stylomandibular and sphenomandibular ligaments are divided and allow removal of the mandibular segment (Prasad and Janecka, 2010). The lateral and medial pterygoid muscles are resected either en bloc with the specimen or separately, depending on tumor invasion. In a subperiosteal manner, the contents of the infratemporal fossa are elevated off the floor of the middle fossa to expose the middle meningeal artery and vein in the foramen spinosum and the mandibular division of the trigeminal nerve in the foramen ovale. The contents of the foramen spinosum are bipolarly Management of Temporal Bone Malignancy 77 Surgical Management of Temporal Bone Malignancy coagulated and divided. Frequently, the venous plexus of the foramen ovale requires bipolar coagulation and packing with oxidized cellulose. The cartilaginous eustachian tube is divided, and the anterior end is sutured closed to prevent postoperative cerebrospinal fluid rhinorrhea (Chung and Pensak, 2005). Management of Temporal Bone Malignancy 78 Surgical Management of Temporal Bone Malignancy Figure 37: A: Incisions vary according to whether the tumor is contained in the temporal bone. B: The facial nerve can be divided peripherally at the distal branches or centrally at the facial nerve trunk, depending on involvement of the parotid gland. C: After osteotomies and removal of the zygomatic arch and mandibular segments, dissection in the infratemporal fossa continues (Prasad and Janecka 2010). Management of Temporal Bone Malignancy 79 Surgical Management of Temporal Bone Malignancy A mastoidectomy is then performed, which skeletonizes the sigmoid sinus and the jugular bulb. Continuing anteriorly, the carotid artery is exposed in its vertical and horizontal petrous segments and may be mobilized anteriorly (Chung and Pensak, 2005). From a subtemporal or middle fossa exposure, the internal auditory canal is identified and opened with cranial nerves VII and VIII divided. Any remaining bony connections are freed. The lines of resection are through the carotid canal at the lateral aspect of the IAC, through the cochlea and the exiting jugular foramen (Chung and Pensak, 2005). The middle and posterior fossa dura is inspected for carcinomatous involvement. Any involved areas are resected, and margins are sent for frozen section pathologic examination. The temporal lobe and cerebellum are also examined, and limited involvement of the inferior temporal gyrus and cerebellum can be resected. When intradural hemostasis is achieved, the dura is closed in a watertight manner using pericranium or fascia lata (Hirsch et al., 2008). Total Temporal Bone Resection Total en bloc resection of the temporal bone with clear margins could be the procedure needed for oncologic control. It includes resection of the petrous apex with the main temporal bone specimen (Sataloff et al., 1988). The vital structures that surround the temporal bone demand that a meticulously controlled approach be performed to avoid catastrophic vascular and neurologic consequences. Even if the carotid artery is to be Management of Temporal Bone Malignancy 80 Surgical Management of Temporal Bone Malignancy sacrificed with the specimen, proximal and distal control must be achieved. Similarly, the brain, dura, and cranial nerves must be dissected and isolated. Although a “no–touch” tumor approach remains the technique to which we aspire, it is often not accomplished to safely obtain access to the petrous portion of the temporal bone (Sataloff et al., 1988). Figure 38: (A) Incision marked out for extended temporal bone excision. (B) First step is to place colored slings around the great vessels in order to ensure vascular control and identify cranial nerves IX, X, XI, and XII prior to completing the supra-omohyoid neck dissection. (C) Wide access and good visualization of the jugular and carotid foramina and skull base is essential before completing the en bloc extended temporal bone excision. (D) View of the large defect on completion of the resection (Moffat, 2009). After completion of subtotal temporal bone dissection, proximal control of the ICA is obtained either at the skull base or in the neck. Distal control is achieved in the floor of the middle cranial fossa via middle fossa craniotomy. The carotid artery is exposed so that a clip can be placed on it Management of Temporal Bone Malignancy 81 Surgical Management of Temporal Bone Malignancy for distal control if necessary. The bone lateral to the ICA at the genu is removed, and the ICA is dissected free from its canal from the skull base to the foramen ovale (Prasad and Janecka 2010). A thick, fibrous ring of tissue surrounds the ICA at the carotid foramen. When mobilizing this portion of the ICA, it is safer to first dissect circumferentially around the fibrous tissue rather than along the carotid itself because the risk of carotid laceration is high. The fibrous ring can be left intact while the ICA is mobilized. Once adequate exposure has been achieved, the remainder of the otic capsule containing the cochlea is drilled (Prasad and Janecka 2010). Anteriorly, the petrous apex is drilled to complete total resection of the temporal bone. The eustachian tube lays inferolateral to the carotid canal at the genu and travels anteromedially. The eustachian tube can be resected anteriorly to the level of the foramen ovale. If cancer is found anterior to this area, nasopharyngeal resection and possibly cavernous sinus dissection will be necessary to achieve total resection. The transected end of the eustachian tube is sutured closed to prevent CSF rhinorrhea (Sataloff et al., 1988). Reconstruction after temporal bone surgery The goals of soft tissue reconstruction after temporal bone resection include alleviation of cosmetic deformity, prevention of CSF leak, and promotion of adequate healing (Hirsch et al., 2008). In most cases, these objectives are best accomplished with a vascularized flap. To prevent communication between the nasopharynx and the middle ear space after lateral temporal bone resection, the eustachian Management of Temporal Bone Malignancy 82 Surgical Management of Temporal Bone Malignancy tube is obliterated by scarifying the mucosa and filling the lumen with bone dust, Surgicel, or a plug of muscle (Hirsch et al., 2008). The resultant defect after lateral resection of the temporal bone is similar to that after radical mastoidectomy, and there is usually little risk of cerebrospinal fluid (CSF) leak, so adequate tissue coverage can be accomplished with a split–thickness skin graft. However, because most patients require radiation therapy after surgery or have previously undergone radiation therapy, so a vascularized flap to promote healing provides the optimal result. The posterior one half of the temporalis muscle is separated from the anterior portion, and while pedicled inferiorly, the posterior portion of the muscle is rotated into the mastoid cavity (Hirsch et al., 2008). The surgical defect after subtotal temporal bone resection extends medially through the otic capsule and poses a greater likelihood of a CSF leak. If infratemporal fossa dissection has not been performed, the resultant defect is not significantly larger than one resulting from lateral temporal bone resection. Usually, a pedicled posterior temporalis flap provides adequate coverage. Other options include a lower island trapezius or pectoralis major myocutaneous flap. If these flaps cannot be mobilized superiorly to cover the temporal bone defect adequately, a free flap with microvascular anastomosis to the superficial temporal or facial artery system can be used. The most commonly used free flap is the rectus abdominis, although a scapular or latissimus dorsi free flap can also be used. The temporomandibular joint is not reconstructed routinely (Hirsch et al., 2008). If the facial nerve has been resected and there is an adequate proximal stump, it is reconstituted with a cable nerve graft. More commonly the sural Management of Temporal Bone Malignancy 83 Surgical Management of Temporal Bone Malignancy nerve is used. The greater auricular nerve can be used if the length required is less than 6 cm. Otherwise, a sural nerve graft is necessary to obtain a longer donor graft for anastomosis between the proximal and distal ends of the facial nerve. If facial nerve resection has been performed distal to the pes anserinus, both the upper and lower branches are reconstructed. If the proximal stump of the facial nerve has been resected at the brain stem with an inadequate length left for anastomosis, a hypoglossal-to-facial (XII to VII) nerve anastomosis can be performed. If a CSF leak is a potential problem, the wound should be closed in at least three layers (Hirsch et al., 2008). Complications of temporal bone resection Aggressive temporal bone resection may be associated with major intracranial complications. Extensive brain retraction can result in lower cranial nerve palsy, cerebellar or temporal lobe edema and dysfunction, and cerebral infarction. Major arterial injuries can cause disastrous consequences, and all precautions should be taken to prevent these injuries. As in the case of dissection of the ICA can result in injury with bleeding and stroke (Ariyan et al., 1981). So intraoperatively, before manipulation of ICA, proximal control of the vessel in the neck or at the skull base and distal control in the horizontal portion of the intrapetrous carotid artery should be obtained. In this way, if an injury to the ICA occurs, rapid control of the situation can be achieved. If a laceration of the ICA occurs, it is managed by either primary repair, repair with a patch, bypass grafting using the saphenous vein, or sacrifice of the ICA without reconstruction. Venous complications are also possible after Management of Temporal Bone Malignancy 84 Surgical Management of Temporal Bone Malignancy temporal bone resection, especially if manipulation or resection of the sigmoid sinus is performed (Ariyan et al., 1981). Another complication is CSF leak. The main morbidity of a CSF leak is increased risk for the development of meningitis. Because meningitis can be a life–threatening condition, prevention plus control of CSF leaks is very important. CSF leaks occur when there is inadequate closure of the dura in conjunction with a path for egress of CSF through the soft tissues to the external environment. The usual sites of leakage are the eustachian tube, incision site, and remnant of the EAC. Prevention is the most efficacious method of management. All dural closures should be made as watertight as possible. Any potential dead spaces should be obliterated by placement of muscular flaps or autologous fat grafts. The final barriers to CSF flow, skin closure and the eustachian tube, should be closed or obliterated in watertight fashion. A drain is not placed in the wound. Postoperatively, the patient's head is kept elevated and the patient is instructed to avoid straining or performing a Valsalva maneuver. A pressure dressing is maintained for 5 days (Skedros et al., 1993). Wound infections occur infrequently after resection of the temporal bone. Appropriate treatment is no different from treatment elsewhere in the head and neck (Hirsch et al., 2008). One of the most rapidly progressive and potentially fatal complications is acute intracranial hemorrhage, which if not treated promptly can lead to irreversible cerebral injury with uncontrolled cerebral edema or brain stem herniation and even death (Hirsch et al., 2008). Management of Temporal Bone Malignancy 85 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Radiotherapy alone has been used to treat ear carcinoma in large radiotherapy centers. Lederman and others showed that in 1965 the overall 5-year survival rate was 24% in patients treated for external canal carcinoma by radiotherapy alone. Arthur reported that radiotherapy alone can achieve an overall 5-year survival rate of 42%. In 1987, Million and Cassisi reported an 80% two year survival rate for patients treated by radiotherapy alone. In 1989, Golding-Wood and others suggested that radiotherapy was the preferred initial treatment in almost all patients (Shiratoa et al., 2000). However, with the development of en bloc resection and plastic surgery, radiotherapy has shifted from being an initial treatment to being an adjunct to surgery in many institutions. In these institutions, the use of radiotherapy alone is reserved as a treatment for inoperable advanced disease, and therefore the survival rate following radiotherapy alone is reported to be very low. Some authors have suggested that conservative surgery combined with definitive radiotherapy is as effective as or more effective than aggressive surgery (Testa et al., 1997). In spite of intraoperative monitoring of margins of resection, many cases showed tumor invasion beyond surgical margins following nerves, vessels, and fasciae. Because incomplete surgical excision is the major reason for treatment failure, postoperative radiotherapy has become an important measure to achieve local control of the disease (Graham et al., 1984). Adenoid cystic carcinomas are a special entity in tumors of the ear, showing a slow proliferation rate and a low tendency of lymphatic spread. However, when excised incompletely, lesions recur locally and the Management of Temporal Bone Malignancy 86 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy prognosis is poor. So a “wait and see” policy without postoperative radiotherapy could only be used in completely en bloc resected patients with adenoid cystic carcinoma. (Perzin et al., 1982). General management in external auditory canal malignancy Tumors of the external ear are most often treated with limited surgery or external radiation therapy. Treatment in early stages with irradiation is usually in the form of electron beam therapy. Surgery is beneficial if the lesion has invaded the cartilage of the ear or extends medially into the middle ear. Advanced lesions involving a significant portion of the ear canal are managed with a combination of irradiation and surgery (Shockley and Stucker 1987). Treatment of draining lymphatics is normally not required for early stages of external ear tumors. Lesions over 4 cm and those with cartilage invasion have an increased risk of nodal spread; so prophylactic neck dissection is recommended. Most investigators do not agree with this approach because the overall chance of lymph node involvement in tumors of the external ear is only 16% (Shiratoa et al., 2000). Interstitial irradiation using after loading 192 Ir, particularly for tumors smaller than 4 cm, is also an effective method of treatment, affording excellent local control (Hammer et al., 1994). Radical surgery and postoperative radiation therapy are the accepted methods of treatment for more advanced lesions of the external auditory canal and lesions in the middle ear and mastoid. Tumors that are detected early, each modality is considered optimal by itself, and a combination of Management of Temporal Bone Malignancy 87 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy the two produces the best results in locally advanced disease (Chao et al., 2008) General management in middle ear malignancy In management of temporal bone tumors originating from the middle ear and mastoid area, surgeons have extended their abilities to resect tumors in these areas owing to advances in surgical techniques, modern neurosurgical anesthesia, intensive care, microsurgery, and cranial base reconstruction with micro vascular flaps (Sekhar et al., 1992). Depending on the tumor extent, the surgical options are mastoidectomy, lateral temporal bone resection, subtotal temporal bone resection, and total temporal bone resection. Postoperative radiation therapy is essential to increase the chance of local tumor control. In studies that suggest limited benefit of postoperative irradiation, the results may be related to the extent of the tumor. Some investigators favor only limited surgery and postoperative irradiation (Prasad & Janecka 1994). Radiation Therapy Techniques Before 1989, a single lateral field in mixed beam technique photon: electron or most frequently, a paired lateral wedged technique was employed for radiation treatment to achieve a better dose distribution (Wang 1975). Since 1989, External beam radiation therapy (EBRT) has been performed by an individualized radiation technique based on CT treatment planning. From 1989 to 1995, dose distributions in multiple sections throughout the target volume were calculated by Oncology Support System Management of Temporal Bone Malignancy 88 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy (Philips), since 1995 true 3D-planning is performed using Treatment Management System (Helax) (Pfreundner et al., 1999). Target volume for treatment of cancer of the EAC includes the petrosal bone, the parotid fossa, including intra- and infraparotideal lymph nodes, ipsilateral retroauricular, upper jugular, and upper spinal accessory lymph nodes. In case of clinical and histological confirmed lymph node metastases, the target volume also includes the locations of the middle and lower groups of the ipsilateral jugular and spinal accessory lymph nodes. In case of histopathological confirmed perineural tumor spread along the facial nerve, the compartment innervated by the ipsilateral facial nerve will be included into the target volume (Pfreundner et al., 1999). Using external beam radiation based on 3D CT-treatment planning, in tumoricidal doses can be administered without a serious threat of brain stem damage and brain injury. The radicality of resection and radiotherapy is a factor influencing local control and survival. Postoperative adjuvant radiotherapy with doses of 54–60 Gy when tumor was resected radically could achieve a good local control and 5-year survival rate. Many cases of late stage cancer of the external auditory canal and middle ear is resected with tumor beyond surgical margins, also with reduced doses in postoperative radiation treatment; this might be the reason for low local tumor control rates. (Shih and Crabtree, 1990). Tumors involving the pinna can be treated with electron beam. The fields can be round or polygonal, drawn around the tumor to spare surrounding normal tissues. For small superficial tumors, margins of 1 cm are adequate. However, more extensive lesions require large portals, which Management of Temporal Bone Malignancy 89 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy may encompass the entire pinna or external canal and require 2-3cm margins around the clinically apparent tumor. Lesions involving the pinna must be treated with low fractionation (1.8 to 2 Gy daily) to prevent cartilage necrosis. Doses of 65 Gy over a period of 6.5 weeks are required to achieve adequate tumor control (Chao et al., 2008). Figure 39: Example of treatment portal for tumor of the middle ear involving the petrous bone. The mastoid is included in the irradiated volume (Chao et al., 2008). Large lesions of the external auditory canal are treated with irradiation alone or combined with surgery; the portals should encompass the entire ear and temporal bone with an adequate margin (3 cm). The volume treated should include the ipsilateral preauricular, postauricular, and subdigastric lymph nodes. Treating lymphatics beyond the jugulodigastric area is usually not necessary. Extremely advanced tumors that are unresectable should be treated with high-energy ipsilateral electron beam therapy (16 to 20 MeV) alone or mixed with photons (4 to 6 MV) or with wedge pair (superior inferiorly angled beams) techniques using low-energy photons. Doses of 60 to 70 Gy over 6 to 7 weeks are required. Doses higher than this may produce Management of Temporal Bone Malignancy 90 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy osteoradionecrosis of the temporal bone. If various types of radiation therapy beams are available, individualized treatment plans should be devised. Patients receiving radiation therapy to the middle ear and temporal bone regions require immobilization devices to avoid target miss. When electron beam radiation therapy is used, use of water bolus in the external auditory canal and concha may reduce the auricular complications. Threedimensional conformal radiation therapy is a valuable technique in the treatment of these tumors (Chao et al., 2008). This volume will be irradiated by a dose of 54–60 Gy. In case of tumor involved surgical margins or residual tumor, boost volume will include the site of the primary tumor and of the lymph node metastases. Boost irradiation will be up to a total dose about 70 Gy (Chao et al., 2008). Management of Temporal Bone Malignancy 91 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Figure 40: Radiation technique for treatment of T3N1 carcinoma of the external auditory canal with involvement of an intraparotideal lymph node and perineural tumor spread along the facial nerve. The peripheral margin of facial nerve was infiltrated by the tumor. (a) Three-field 5 MV-technique for treatment of potential tumor invaded structures (applied dose 56 Gy, single dose 2 Gy). The fields from 273° to 337° are forming the triangular dose distribution predescribed by the planning-target volume. The field from 0 degree is filling up the dose in the depth, and spares the brain stem. All fields are wedged for homogenization of the dose distribution, field from 337° with the tip in cranial direction. It compensates the dose loss caused by the increase of the patient’s diameter. (b) Three-field wedged technique (290°, 230°, 0°), forming a triangular dose distribution covering the tumor bed for boost irradiation (applied dose 14 Gy, single dose 2 Gy) (Pfreundner et al., 1999). Extension of the disease beyond the dura mater is a sign of unresectability and incurability. Therefore, the palliative EBRT appears to be the adapted treatment for these patients. Recurrences after surgery and EBRT exhibit a poor prognosis. Brachytherapy is a treatment option which can be applied in curative intent when the disease is locally confirmed. Many authors concluded that brachytherapy can be used to achieve local control in small volume recurrences at previous irradiated sites (Martinez et al., 1991). Management of Temporal Bone Malignancy 92 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Figure 41: Dose distribution for brachytherapy treatment of EAC recurrence. 3D CTbased treatment was performed after surgery and a full course of EBRT (70 Gy). A mold containing seven applicators was inserted in the cavity of resection. The reconstructed applicator model is superimposed on the planning CT study. The target volume is defined in the CT scans. (a) Planning-target volume and dose distribution in the region of the upper border of the cavity of resection. (b) Planning-target volume and dose distribution at the level of the mandibular joint. The 2 Gy isodose corresponds to the reference isodose. (c) 3 D-patient model with the reference isodose surrounding the target volume (Pfreundner et al., 1999). Management of Temporal Bone Malignancy 93 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Palliative Radiation Therapy Radiation therapy offers significant palliation in recurrent or advanced disease. Pain relief is reported in 61% of patients with tumors of the auditory canal and middle ear. Recurrences developing after previous irradiation may be retreated with low-dose radiation therapy and hope for control of tumor. When a small-volume local recurrence occurs after previous radiation therapy, fractionated high dose-rate treatment may be considered (Martinez et al., 1991). Results of radiotherapy The series of patients reported from several institutions are small. In more extensive lesions, combinations of surgery and irradiation have yielded satisfactory results. Overall 5-year survival rates with combination therapy for tumors involving the middle ear and external auditory canal range from 40% to 60%, with patients with earlier-stage tumors achieving a 70% survival rate at 5 years with no evidence of disease (Hammer et al., 1994). Sequelae of radiotherapy Radiation therapy sequelae include cartilage necrosis of the external auditory canal and osteoradionecrosis of temporal bone. Very rarely, secondary infection and meningitis are reported. Because of the proximity of the brainstem and medulla oblongata, it is extremely difficult to deliver a high dose of irradiation to the temporal bone without a significant risk of injury to these structures. An overall 10% incidence of bone necrosis can be expected after administration of 60 to 65 Gy. After external ear lesions are treated with interstitial irradiation, there is a 4% incidence of late cutaneous Management of Temporal Bone Malignancy 94 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy and cartilage necrosis. Risk of necrosis increases for lesions over 4 cm (Chao et al., 2008). Stereotactic Radiosurgery Stereotactic radiosurgery and radiotherapy are techniques to administer precisely directed, high-dose irradiation that tightly conforms to a target to create a desired radiobiologic response while minimizing radiation dose to surrounding normal tissue (Mendenhall et al., 1996). Stereotactic radiosurgery evolved from the pioneering work reported in 1908 by Horsley and colleagues. They developed a tool that could localize an intracranial structure in three dimensions, enabling the insertion of a needle electrode. Using this apparatus in a monkey brain, Horsley and Clarke were the first to describe the stereotactic destruction of an intracranial target using electrode electrocoagulation (Horsley and Clarke, 1908). Spiegel and colleagues began developing the first stereotactic device for human use in 1947. Their device was fixed to the patient’s head in much the same way as Horsley and Clarke’s (Spiegel et al., 1947). Lars Leksell is known as the father of stereotactic radiosurgery for his pioneering work applying the stereotaxic technique to radiation delivery. Leksell1 developed his stereotactic apparatus for intracerebral surgery in 1947. The device enabled the precise placement of a needle or electrode into a desired location within the human brain. Leksell first described the concept of stereotactic radiosurgery in 1951. The initial device used a collimated xray beam (gamma rays) that could move along the semicircular arch of his stereotactic apparatus to strike an intracranial target (Leksell, 1951). Management of Temporal Bone Malignancy 95 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy In 1960, Leksell and colleagues performed their first human stereotactic proton beam operation at the Gustaf Werner Institute in Uppsala. About the same time, Woodruff and colleagues introduced a similar cyclotron-based radiosurgery system and began irradiating pituitary lesions. Leksell eventually settled on gamma rays as a practical compromise for stereotactic radiosurgery. The first gamma unit was installed in Sweden, in 1968. The device used 179 sources of cobalt-60 distributed with collimators to create a sharply circumscribed disc-shaped lesion. The second gamma unit was installed in Stockholm, Sweden, in 1974. This updated version was designed specifically for stereotactic radiosurgery (Leksell et al., 1960; Woodruff et al., 1984; Leksell, 1983). Target localization improved dramatically when CT was used in conjunction with the stereotactic apparatus. Leksell described the application of CT during radiosurgery and noted the technique enabled rapid and accurate target localization. With the advent of better imaging methods, solid tumors became radiosurgical targets. Leksell believed stereotactic radiosurgery was a logical approach to decrease the morbidity and mortality if compared to surgery (Leksell et al., 1980). By 1985, Leksell and colleagues reported the potential application of MRI to radiosurgery, pointing out the many advantages of this detailed imaging modality (Leksell et al., 1985). Today CT, MRI, and angiography are used commonly during radiosurgical planning (Lasak & Gorecki, 2009). So we have a treatment option, that could be stereotactic radiosurgery or stereotactic radiotherapy (fractionated stereotactic radiosurgery). It is used Management of Temporal Bone Malignancy 96 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy in patients who are not candidates for resection because of preference, infirmity, or age (65 years or older). So they can be treated with either external beam radiotherapy or stereotactic radiosurgery. In general, stereotactic radiosurgery is preferred, because it is probably at least as effective as fractionated external beam irradiation and is considerably less time consuming. The risk of a major complication after stereotactic radiosurgery is probably similar to that associated with external beam irradiation. There is considerable interest in the development of stereotactic radiotherapy, in the hope of achieving local control rates comparable with those obtained by both external beam irradiation and stereotactic radiosurgery but with less morbidity. This is a reasonable option for the elderly patient in poor health with a limited tumor (Mendenhall et al., 1996). Radiation therapy techniques Stereotactic radiosurgery may be delivered with a particle beam, a gamma knife, or a linear accelerator. The cost associated with particle beam therapy is more than for the gamma knife or linear accelerator. Disadvantages of the gamma knife are that it is also expensive, it requires 201 cobalt-60 sources that must be replaced periodically, and it can only be used for stereotactic radiosurgery. The linear accelerator based system is an effective method of delivering stereotactic radiosurgery and is much less expensive than the other two alternatives. An additional advantage is that the linear accelerator can be used for conventional external beam irradiation when it is not being used for radiosurgery. The Brown-Roberts-Wells (BRW) frame is attached to the patient's skull. A stereotactic CT with or without MRI is then obtained in the axial plane and is used to plan the Management of Temporal Bone Malignancy 97 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy treatment. Stereotactic radiosurgery is delivered with 6 MV X-rays using multiple noncoplanar arcs (Mendenhall et al., 1996). Figure 42: Stereotactic radiosurgery technique (A, B) Treatment is delivered through up to nine non coplanar arcs intersecting at the isocenter of the target. (C) The location of the arcs relative to the calvarium is indicated (Friedman et al., 1992). Management of Temporal Bone Malignancy 98 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy In 1997, Adler introduced the Cyberknife. It is a frameless stereotactic radiotherapy system that mounts a lightweight (130 lb) 6 mV linear accelerator on a highly mobile robotic arm. This revolutionary design incorporates a real-time guidance system, which obviates the need for rigid fixation as used in frame base systems. Cyberknife determines the location of the skull or spine in the coordinate frame of the radiation delivery system by comparing digitally reconstructed CT phantoms obtained from the patient’s treatment planning images with real-time oblique radiographs obtained during the procedure. (Chang and Adler, 2001). Figure 43: John Adler and the Cyberknife (Lasak & Gorecki, 2009). Management of Temporal Bone Malignancy 99 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Now, the medical community has a well-founded combination of anticipation and expectation for noninvasive treatment methods. The potential for decreased morbidity and improved quality of life with the use of radiosurgery and radiotherapy is being realized. There is a growing involvement outside of neurosurgery and radiation oncology, such as neurotologists, thoracic surgeons, general surgeons, and urologists. Stereotactic radiosurgery and radiotherapy will continue to advance treatment options for patients, and the future of this evolving field should be interesting (Lasak & Gorecki, 2009). Chemotherapy The role of chemotherapy in the treatment of temporal bone malignancy has not been determined, but interest in its use is growing. Because of the low incidence and the histologic diversity of temporal bone malignancies. Temporal bone malignancies of salivary gland origin, similar to salivary malignancies in other sites, do not usually respond to currently available chemotherapeutic agents. Squamous cell carcinoma of the temporal bone may respond to platinum-based agents, but typically the results are not durable, and other modalities must be used. For these reasons, most patients with temporal bone cancer are treated with surgery, radiation, or a combination of the two, and chemotherapy is usually reserved for palliation in patients with distant metastases or recurrences (Arriaga and Leonetti, 2010) Chemotherapy has been shown to be effective for rhabdomyosarcoma (Leonetti and Marzo, 2002). Management of Temporal Bone Malignancy 100 Radiotherapy and Stereotactic Radiosurgery in Temporal Bone Malignancy Nakagawa and others, published data that suggest a possible role for preoperative chemoradiation therapy in the treatment of T3 and T4 squamous cell carcinoma. The radiation-enhancing effect of chemotherapy may be useful in reducing the tumor burden and improving control of the surgical margin. They showed improved survival rates for T4 lesions not involving dura, pyramidal apex, carotid canal, or lymph nodes that are as good as survival rates in patients with T3 lesions (Nakagawa et al., 2006). Management of Temporal Bone Malignancy 101 Prognosis and Outcome of Temporal Bone Malignancy Prognosis and Outcome of Temporal Bone Malignancy It is difficult to meaningfully compare the treatment outcome of temporal bone malignancy for several reasons. Temporal bone malignancy is so rare that no one center has extensive experience with treatment. Lack of universally accepted staging systems and the wide variety of treatment protocols applied make comparison of results difficult. No prospective study comparing different treatment protocols has been carried out as yet (Moffat, 2009). The local extent of tumor at diagnosis is an important prognostic indicator. In most studies the cure rate is high when the disease is lateral to the tympanic membrane. When disease is detected early and limited to the external canal a lateral temporal bone resection can be performed. More extensive disease extending into the middle ear and surrounding structures including dura, brain, pterygoid muscles, otic capsule, and carotid carries a worse prognosis and hence the extent of surgery must be according to the disease stage (Moffat, 2009). However, if the disease is confined to the EAC. No statistically significant difference in 5-year survival was found between patients treated with LTBR and patients treated with STBR. When disease extended into the middle ear, patients who had STBR had better 5-year survival than patients who had LTBR. The experience with carcinoma that invaded the petrous apex is limited. But patients then will be treated with TTBR (Prasad and Janecka, 2010) Regarding the value of preoperative or postoperative radiation therapy, when the disease is confined to the EAC, the addition of either preoperative or postoperative radiation therapy to LTBR did not Management of Temporal Bone Malignancy 102 Prognosis and Outcome of Temporal Bone Malignancy significantly improve 5-year survival. But in more aggressive disease, radiotherapy has a vital rule for local control and improving the survival rate (Prasad and Janecka, 2010). When the disease extends into the middle ear a lateral temporal bone resection will offer a 28.7% survival rate. Whereas a more extensive subtotal temporal bone resection has a 41.7% five-year survival. More recently the cure rates for T3 and T4 tumors are reported between 35–47% (Moffat et al., 2005). This highlights the importance of aggressive en bloc resection. Moffat in an early review in 1997 reported his data on 15 patients who underwent either a lateral temporal bone resection or for more advanced disease extended temporal bone resection. He achieved an overall outcome of 47.5% five-year survival. A more recent review in 2005 of 39 patients revealed that survival for stage I and II disease was 100% and for stage III and IV disease was 43%. This again demonstrated the increased survival of early stage disease and the importance of early diagnosis and aggressive surgical management (Moffat et al., 2005). Moffat and Moody both recommend an en bloc resection and Moody proposes that a prospective protocol be developed in which each skull base unit follows a progression of treatment that is specific for each stage of the disease based on a consistent staging system. For early lesions a modified temporal bone resection or a lateral temporal bone resection (LTBR) is performed, with more advanced lesions a subtotal temporal bone resection (STBR) or a total temporal bone resection (TTBR) should be the treatment Management of Temporal Bone Malignancy 103 Prognosis and Outcome of Temporal Bone Malignancy of choice. Moffat takes a more aggressive approach than this and states that the minimal procedure for disease lateral to the tympanic membrane should be a LTBR and superficial parotidectomy. For T3 and T4 disease an extended temporal bone resection and total parotidectomy with facial nerve sacrifice offers the greatest chance of cure. Half the recurrences are in the first 12 months following treatment and 85% of recurrences occur within three years of treatment. Recent evidence suggests that treatment for advanced and recurrent cancer in the form of extended temporal bone resection and postoperative radiotherapy results in improved five-year survival rates of 47% (Moffat et al., 1997). Specific Outcome Issues Nodal Disease Twenty-three percent of the 39 patients in Moffat’s series had nodal disease at presentation, confirmed by histology following radical neck dissection. He considered that this was a significant prognostic indicator in his series. Death was always due to local recurrence and hence it was believed that nodal disease is a good indicator of aggressive disease (Moffat et al., 2005). Histology Generally undifferentiated tumors had a poorer prognostic outcome than moderately and well-differentiated tumors. Positive histological margins at the time of resection, not surprisingly, are a poor prognostic indicator in this locally aggressive disease. Death in these patients usually occurs within 12 months (Moffat et al., 2005). Management of Temporal Bone Malignancy 104 Prognosis and Outcome of Temporal Bone Malignancy Basal cell carcinoma has a propensity for deep local invasion and perineural spread with metastases being rare. Primary melanoma of the temporal bone is extremely rare with a very poor prognosis (Moffat et al., 2009). Adenoid cystic carcinomas are the most common glandular tumors. Adenocarcinomas are usually well differentiated low-grade papillary cancers. The long-term prognosis for high-grade adenocarcinoma and mucoepidermoid carcinoma is poor. In contrast, survival after adenoid cystic carcinoma can be lengthy even in the presence of metastases (Glasscock et al., 1987). Chondrosarcoma of the temporal bone is extremely rare. These tumors may be indolent and present late. They tend to invade locally and metastasize late. They may extend outside the temporal bone and into the cerebellopontine angle. Radical surgery and postoperative radiotherapy is the treatment of choice (Moffat et al., 2009). Rhabdomyosarcoma is a rare aggressive tumor almost exclusively limited to childhood age groups. The mean age at presentation is five years. Until recently the prognosis has been extremely poor, but following the multimodality treatment (surgical resection, followed by radiotherapy and chemotherapy) protocol recommended by The Intergroup Rhabdomyosarcoma Study Committee, treatment outcomes have greatly improved. Recurrent sarcoma tends to spread early to the lungs and bone, and intracranially to involve multiple cranial nerves (Wiatrak and Pensak, 1989). Management of Temporal Bone Malignancy 105 Prognosis and Outcome of Temporal Bone Malignancy Dural and Cerebral Involvement Brain involvement is usually associated with a poor outcome. In Moffat’s series dural involvement alone was not a significant prognostic indicator. (Moffat et al., 2005). Carotid Invasion Invasion of the carotid artery signifies extensive disease progression. Both Gillespie and Moffat no longer consider carotid resection. In the series described by Moffat of the seven patients with perivascular involvement of the carotid, only one is alive at a follow up of six months. Gillespie reports two patients with carotid involvement both of whom have died of their disease within months of treatment. Moody successfully resected the carotid in one patient who is still alive, but no comment was made with regards to neurological status in this case (Gillepsie et al., 2001). De Novo versus Salvage If patients had undergone any treatment at any institution, so any further treatment is considered salvage. Patients with no previous treatment are defined as de novo cases. Although the numbers were too small to make any statistical analysis the trend showed poorer outcomes for the salvage patients. This would support the concept that the first treatment protocol offers the greatest chance of cure and should be aggressive (Moffat et al., 2009). Management of Temporal Bone Malignancy 106 Report of a case Report of a case A 21 year old man presented to kasr Al Aini university hospital with long history of unresolved chronic suppurative otitis media with left facial paralysis. The patient was underwent left ear exploration. Abnormal tissue was seen during the operation, so radical mastoidectomy was done and biopsy was taken for histopathological examination. The result showed squamous cell carcinoma. Figure 44: Close up view showing the lateral extent of the mass encroaching on the concha. After that, CT scan was done revealed destructive lesion involving the left external auditory canal, middle ear, mastoid and reaching the petrous apex short of the carotid artery, with erosion of the tegmen tympani. No intracranial extension was found. According to that, he was staged T4 N0 temporal bone squamous cell carcinoma. Management of Temporal Bone Malignancy 107 Report of a case He underwent left total temporal bone resection. Figure 45: Operative view showing markings including: 1. The incision. 2. Temporalis muscle borders. 3. Zygomatic arch. 4. Mandible. 5. Sternomastoid muscle and trapezius. 6. Mastoid process. Figure 46: Intraoperative view showing the incision. Note: preservation of the auricular framework. Management of Temporal Bone Malignancy 108 Report of a case Figure 47: Intraoperative view showing anterior and posterior flap elevations before surgical dissection. Figure 48: Intraoperative view after neck dissection and temporal craniotomy showing: 1. Temporalis muscle. 2. Outline of temporal craniotomy. 3. Outline of specimen before resection. 4. Cut facial nerve (tagged). 5. Cut internal jugular vein (tagged). Management of Temporal Bone Malignancy 109 Report of a case Figure 49: Intraoperative view after resection showing: 1) Temporal lobe dura. 2) cerebellum. 3) Internal carotid artery. Note: the lower four cranial nerves are numbered. Management of Temporal Bone Malignancy 110 Report of a case Figure 50: The specimen (lateral aspect). Figure 51: Immediate postoperative view. Note marginal skin ischemia of the auricle that resolved completely after 1 month. Management of Temporal Bone Malignancy 111 Report of a case Postoperative radiation therapy was done and ended in December 2007. Follow up CT was done every three months for the first year, then every six months in the second year with no evidence of recurrence. After thirty months, there is no evidence of recurrence and he is at the present time a candidate for dynamic facial reanimation using free muscle flap. Management of Temporal Bone Malignancy 112 Summary Summary The temporal bone is a composite structure consisting of the tympanic bone, mastoid process, squama (also known as the squamous portion of the temporal bone), and petrosa (also known as the petrous portion of the temporal bone). Although the styloid process is closely related to the temporal bone, it is not considered a portion of it. It contains the structures of the middle ear and inner ear. Also it is related to vital structures as the temporal lobe and the internal carotid artery. According to different histological structures in the temporal bone there are many tumors could arise either from external auditory canal or the middle ear. Carcinomas as squamous cell carcinoma, basal cell carcinoma, malignant melanoma and adenexal carcinomas. Sarcomas as angiosarcoma, chondrosarcoma and rhabdomyosarcoma. Each type has its own behavior and presentation. Malignant tumors of temporal bone could spread directly to involve surrounding tissues as parotid gland anteriorly through fissures of santorini. Superiorly to involve temporal lobe, deeply to involve middle ear structures facial nerve and inner ear reaching to the internal carotid and petrous apex. In general, temporal bone malignancy has low incidence of lymphatic and distant metastasis but if present it carries very poor prognosis. Age incidence in temporal bone malignancies usually above 60 years except in case of rhabdomyosarcoma that present in younger age groups. The presentation is usually in the form of bloody otorhea, hearing loss or aural polyp. Management of Temporal Bone Malignancy 113 Summary On examination we can see suspicious granulations that bleed on touch or tumor mass itself. For accurate diagnosis of temporal bone malignancies biopsy must be taken from the suspicious polyp or tumor mass. Also computed tomography and magnetic resonance imaging play very important rule in tumor staging to know extensions of the tumor if vital structures as internal carotid artery is affected or not. Also MRI is superior on CT in diagnosing soft tissue involvement and perinural spread of tumors. Magnetic resonance angiography can be done also to detect carotid and big vessel affection. Recently fusion between CT and MRI is used for better visualization of temporal bone tumors. Management of malignant tumors of temporal bone could be through surgery, radiotherapy or a combination of both. The role of chemotherapy is generally limited and it is beneficial only in case of rhabdomyosarcoma. It is used also for palliation to control distant metastasis. The treatment program depends primarily on the extent of the cancer. Cancer limited to the EAC (T1, T2) should be treated by lateral temporal bone resection with superficial parotidectomy and preservation of the facial nerve. Rarely, the cancer may be small, isolated in the lateral cartilaginous aspect of the EAC, and not eroding bone, thereby permitting sleeve resection of the external canal skin, lateral to the tympanic membrane. In practice, sleeve resection is probably not oncologically adequate. Management of Temporal Bone Malignancy 114 Summary Cancer that has invaded the middle ear and mastoid cavities (T3) is treated by subtotal temporal bone resection. Total temporal bone resection (sometimes called Radical temporal bone resection) is performed when cancer extends to the petrous apex. Cancer extending to the temporomandibular joint (TMJ), neck, dura, or Infratemporal fossa (T4) will require resection of these structures. Radiotherapy is essential in the treatment of temporal bone malignancy especially if combined with surgery for adequate local control of the disease. It improves the prognosis of large lesions, in case of positive margins and in recurrence after surgery. 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Auris Nasus Larynx; 35(2): 276-281 Management of Temporal Bone Malignancy 133 الملخص العربي الملخص العربي اٌعظُ ا ٌصذغ ٛ٘ ٟعظُ ِعمذ اٌزشو١ت ٠زى ِٓ ْٛعذح أخزاء ٠ٚحز ٞٛعٍ ٝأعضبء ٘بِخ خذا ِٕٙب األرْ اٌٛسطٚ ٝاالرْ اٌذاخٍ١خ اٌّسؤٌٚخ عٓ اٌسّع ٚاالرزاْ ف ٟاالٔسبْ .وّب أٔٗ ٛ٠خذ ثدٛاس أخزاء ٘بِخ خذا ِٕٙب اٌفص اٌصذغٌٍّ ٟخ ٚاٌشش٠بْ اٌسجبر ٟاٌذاخٍ. ٟ ٚفمب ٌٍ١ٙبوً إٌس١د١خ اٌّخزٍفخ ف ٟاٌعظُ اٌصذغٕ٘ ٟبن اٌعذ٠ذ ِٓ األٚساَ اٌزّ٠ ٟىٓ أْ رٕشأ ِٕٙبٚ.رمسُ ٘زٖ األٚساَ بالنسبة لمنشئها ،إِب أْ رٕشأ ِٓ األر ن الخارجية بما فيها صوان األذن ٚ اٌمٕبح اٌسّع١خ أ ٚاألرْ اٌٛسطٚ ٝاٌذاخٍ١خ. ِٓ ٘زٖ األٚساَ :األٚساَ اٌظب٘ش٠خ ِثً سشطبْ اٌخال٠ب اٌمبعذ٠خ ٚاٌسشطبٔبد اٌغذ٠خ ٚاٌسشطبٔبد اٌحششف١خٕ٘ٚ .بن اٌسشطبٔبد اٌٍحّ١خ اٌز ٟرظٙش ِٓ األٚع١خ اٌذِ٠ٛخ ٚاٌخال٠ب اٌعضٍ١خ اٌّٛخٛدح ثعظّخ اٌصذغ . ٕ٘ٚبن أٚساَ لذ رٕشأ ِٓ األعضبء اٌّزبخّخ ٌعظّخ اٌصذغ ٚرٕزشش إٌٙ١ب عٓ طش٠ك اإلٔزشبس اٌّجبشش.أ ٚلذ رٕشأ ِٓ أعضبء ثع١ذح عٓ عظّخ اٌصذغ ٚرصً اٌٙ١ب عٓ طش٠ك اٌذَ. ٌألٚساَ اٌخج١ثخ ٌعظبَ اٌصذغ اٌمذسح عٍ ٝأ٢زشبس ِجبششح إٌ ٝاألٔسدخ اٌّح١طخ ثٙب ِثً اٌغذح إٌىف١خ ِٓ خالي شمٛق سبٔزٛسٚ ٟٕ٠وزٌه إٌ ٝاٌفص اٌصذغٌٍّ ٟخٚ.رٕزشش ف ٝاٌعّك إٌِ ٝحز٠ٛبد األرْ اٌٛسطِ ٝثً عصت اٌٛخٗ ثُ إٌ ٝاألرْ اٌذاخٍ١خ حز ٝرصً إٌ ٝاٌشش٠بْ اٌسجبر ٟاٌذاخٍ.ٟ ٚثصفخ عبِخ ،يألٚساَ اٌخج١ثخ ٌعظبَ اٌصذغ ِعذي ِٕخفط ٌالٔزشبس ٌٍغذد اٌٍّفب٠ٚخ ٚاٌذَ ٌٚىٓ إرا حذس رٌه رى ْٛإٌزبئح اٌّزٛلعخ ٌٍعالج س١ئخ . ٠زشاٚذ سٓ األصبثخ ةاألٚساَ اٌخج١ثخ ف ٟعظبَ اٌصذغ ِٓ سز ٓ١سٕخ فأوثش ِبعذا ف ٟثعط األٚساَ اٌٍحّ١خ اٌخج١ثخ ٕ٠خفط ِزٛسظ اٌعّش اٌ ٝاٌفئبد األصغش سٕب . عبدح ٠ظٙش اٌّشض عٍ ٝشىً اٌزٙبة صذ٠ذِ ٞزِٓ ثبألرْ ال٠سزد١ت ٌٍعالخبد اٌذٚائ١خ أ ٚعٍٝ شىً سٍٍ١خ خبسخخ ِٓ األرْ ٚاٌز ٟرؤد ٞأٌ ٝز٠ف عٕذ ٌّسٙبٚ .لذ ٠ظٙش اٌّشض ثبعشاض أزشبس اٌٛسَ ِثً شًٍ اٌعصت اٌّخ ٟاٌسبثع أٚ ٚسَ ثبٌغذح إٌىف١خ ا ٚاٌعمذ اٌٍّ١فب٠ٚخ اٌعٕم١خ. 1 عالج األورام الخبيثة لعظمة الصدغ الملخص العربي ٌٍحصٛي عٍ ٝاٌزشخ١ص اٌذل١ك ٌألٚساَ اٌخج١ثخ ٌعظبَ اٌصذغ ٠دت أْ رؤخز عٕ١خ ِٓ اٌٛسَ وتحلل ثبثٌٛٛخ١ب .وّب أْ األشعخ اٌّمطع١خ ٚاٌشٔ ٓ١اٌّغٕبط١سٍ٠ ٟعت دٚس ٖ اَ خذا ف ٟرشخ١ص اٌٛسَ ٌّعشفخ ِذ ٜأزشبسٖ ٌألٔسدخ اٌّدبٚسح ٚرٌه ٌزحذ٠ذ أٔست اٌطشق اٌعالخ١خ س ٛاء وبٔذ عٓ طش٠ك اٌعالج اٌدشاح ٟأ ٚاإلشعبع.ٟ عالج األورام الخبيثة لعظمة الصدغ يمكن أن يكون عن طريق الجراحة أو اإلشعاع أو مزيج من االثنين معا. بالنسبة لدور العالج الكيميائي فإنه مقصور فقط على بعض األورام اللحمية الخبيثة وكذلك في عالج االنبثاثات البعيدة من الورم. برنامج العالج الجراحي لألورام الخبيثة لعظمة الصدغ يعتمد أساسا على مدى امتداد الورم داخل العظمة وخارجها .وبالتالي يمكن أن يكون في صورة استئصال جزئي أو شبه كلي أو استئصال كلي لعظمة الصدغ. بالنسبة للعالج االشعاعي إما أن يكون هو أساس العالج وذلك في حالة األورام الصغيرة في حجمها والمحدودة في إمتدادها .أو يكون مكمال للعالج الجراحي في حالة األورام االكبر حجما و األكثر امتدادا. من الصعب تحديد تكهن كافي وصحيح في عالج االورام الخبيثة لعظمة الصدغ وذلك ألسباب عدة منها ندرة هذه األورام وعدم توفر احصائيات ودراسات دقيقة لهذه الحاالت وكذلك لعدم وجود نظام عالجي متفق عليه عالميا. بشكل عام يكون التكهن سيئا اذا وجد أن الورم امتد الى أعضاء هامة مثل الفص الصدغي للمخ والشريان السباتي الداخلي .ويكون جيدا اذا تم اكتشاف الورم في مرحلة مبكرة وتم استئصاله كليا بالجراحة وتم اعطاء العالج اإلشعاعي المكمل له. 2 عالج األورام الخبيثة لعظمة الصدغ عالج األورام الخبيثة لعظمة الصدغ رسالة مقدمة من الطبيب أحمد فتحي محمد الدحن توطئة للحصول على درجة الماجيستير في األذن واألنف والحنجرة تحت اشراف أ.د / .اسماعيل زھدي أستاذ األذن و األنف و الحنجرة كلية الطب جامعة القاھرة أ.د / .لؤي الشرقاوي أستاذ األذن و األنف و الحنجرة كلية الطب جامعة القاھرة د /باھر عاشور مدرس األذن و األنف و الحنجرة كلية الطب جامعة القاھرة ٢٠١٠