Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Temporal bone fractures: CT findings Poster No.: C-489 Congress: ECR 2009 Type: Educational Exhibit Topic: Head and Neck Authors: S. Rosa, E. Domènech, M. Larios, C. Delgado, D. Villa, T. Sempere; Tarragona/ES DOI: 10.1594/ecr2009/C-489 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myESR.org Page 1 of 41 Learning objectives Petrous bone is the most common place of skull base fractures. The purpose of this poster is: Ø To review anatomic relationships of temporal bone and adjacent structures (blood vessels, nerves). Ø To identify and describe CT findings of the 3 types of petrous bone fractures (longitudinal, transverse and mixed or oblique) and to know complications associated to them. Background ANATOMIC REVISION OF TEMPORAL BONE: Ø Temporal bones are important paired lateral estructures which are part of the skull base (they form the posterolateral floor of middle cranial fossa). Ø Have a straight relationship with internal carotid artery, internal jugular vein, vestibulocochlear and facial nerves. Ø Divided in 5 different portions: (Fig. 1 and 2) 1. 2. 3. 4. 5. Squamous: forms lateral wall of middle cranial fossa Petrous: pyramidal shape, contains middle and inner ear Mastoid: postnatal developement Tympanic: forms most of bony external ear Styloid: are two bilateral inferior projections Page 2 of 41 Fig.: 1. Squamous portion 2. Petrous portion3. Mastoid portion Page 3 of 41 Fig.: 1. Squamous portion 2. Petrous portion 3. Mastoid portion 4. Styloid portion 1. EXTERNAL EAR: (Fig. 3) Ø Function: to lead and amplify sound waves towards the tympanum Ø Consists of the auricle or pinna and the external auditory canal (EAC) Ø EAC forms an S-shaped curve and as it extends from the auricle to the tympanic membrane. Lateral 1/3 of external auditory canal is cartilaginous and medial 2/3 are osseous (narrower than cartilaginous part). Ø The tympanic membrane is frontier between external and middle ear, it marks medial limit of EAC and lateral limit of middle ear. Fig.: Shows external auditory canal cartilaginous (EACc) and osseous (EACo) segments to the tympanic membrane (arrow) 2. MIDDLE EAR: Ø Function: to transmit and amplify, across the ossicular chain, vibrations that come into contact with the tympanic membrane causing deflection of the oval window (which is attached to the footplate of the stapes) Ø Contains: ossicular chain (which consists of the malleus, the incus, and the stapes) (Fig. 4, 5 and 6), muscles (tensor tympani and stapedius muscle), chorda tympani nerve (branche of facial nerve) Page 4 of 41 Fig.: Head of malleus (yellow arrow)Short process of incus (red arrow), Prussak space (green arrow) Page 5 of 41 Fig.: Manubrium of malleus (yellow arrow), stapes (red arrow), long process and lenticular process of incus(blue arrow) Page 6 of 41 Fig.: 1. Malleus head 2. Malleus manubrium 3. Incus body 4. Incus long process 5. Stapes head 6. Anterior crura of stapes 7. Posterior crura of stapes 8. Epitympanum 9. Mesotympanum 10. Hypotympanum 11. External auditory canal Ø Divided in three different parts: (Fig. 7a and 7b) 1. EPYTYMPANUM: tegmen tympani is the roof and the floor is a line from scutum to 2. 3. tympanic portion of facial nerve. Tegmen tympani is a thin bony sheet separating tympanic cavity from duramater of middle cranial fosa. MESOTYMPANUM: tympanic cavity in strict sense HYPOTYMPANUM: floor of tympanic cavity. Does not contain vital structures Page 7 of 41 Fig.: Green line represents imaginary limit floor from scutum (3) to tympanic portion of facial nerve (1). Tegmen tympani (2) represents the roof. Fig.: Green lines represent imaginary limits for roof and floor of mesotympanum. Red line marks tympanic membrane. 3. INNER EAR: (Fig. 8) Ø Function: once sound wave energy arrives to oval window is transmitted to the fluid of the cochlea and converted by the hair cells of Corti's organ into nerve impulses that are transmitted across the auditory nerve to the brain. Ø Can be distinguished 3 different parts: 1. BONY LABYRINTH: CT has a great sensibility to visualize it. Contains perilympha. Located inside petrous portion of temporal bone. Consists of: Page 8 of 41 • • • • Cochlea (snail shell shape): contains organ of Corti, the sensory organ of hearing Vestibule: organ involved with balance Semicircular canals (superior, posterior and lateral): detect angular acceleration Vestibular and cochlear aqueducts 2. MEMBRANOUS LABYRINTH: Can be studied by MR. Contains endolympha. Housed within bony labyrinth. Complex series of interconnected membranous sacs and ducts. Has four components: • • • • Vestibule (utricle and saccule) Semicircular canals Endolymphatic duct and sac Cochlear duct 3. INTERNAL AUDITORY CANAL (IAC): It is a narrow duct located at posterior and medial surface of petrous bone. Contains facial and vestibulocochlear nerves (VII and VIII), which reach inner ear from brainstem. Page 9 of 41 Fig.: Internal auditory canal (IAC), cochlear foramen (black arrow), cochlea (red arrow), vestibule (pink arrow)semicircular posterior conduct (blue arrow), oval window (green arrow), mastoid sinus (*) 4. VESSELS AND NERVES: (Fig. 9 and 10) Ø INTERNAL CAROTID ARTERY: crosses apex petrous portion of temporal bone through carotid canal. Petrous segment of internal carotid artery (C2) has a vertical caudal part and an horizontal cranial segment which turns cephalad across lacerum foramen (C3) and becomes cavernous segment (C4). Ø INTERNAL JUGULAR VEIN: origins in jugular foramen, located in the apex petrous. Consists in the caudal continuation of sigmoid sinus. Page 10 of 41 Page 11 of 41 Fig.: 1. Carotid canal 2. Lacerum foramen 3. Jugular foramen 4. Sigmoid sinus Fig. 9 Ø VESTIBULOCOCHLEAR NERVE (VIII): is a sensory nerve within internal auditory canal. Innervates vestibule (utricle and saccule), semicircular canals and cochlea. It consists of the cochlear nerve, carrying information about hearing, and the vestibular nerve, carrying information about balance. Ø FACIAL NERVE (VII): presents one motor root and a sensitive smaller root. Can be divided in four different parts: 1. 2. 3. 4. First or internal auditory canal segment (anterosuperior location within IAC) Second or labyrinthine segment: short segment which lies superior to the cochlea and has an anteromedial course. Later makes an anteromedial turn to reach the geniculate ganglion, in this location it presents a posteroinferior turn to form anterior genu. Third or tympanic segment: runs inferolateral to the lateral semicircular canal and extends to posterior genu (where facial nerve changes to a more vertical direction). Fourth or mastoid segment: vertical course inside mastoid process of temporal bone to exit through stylomastoid foramen. Fig.: Labyrinthine segment (light green arrow). Anterior genu (yellow arrow). Tympatic segment (pink arrow). Posterior genu (light blue arrow). Mastoid segment (black arrow) Page 12 of 41 Stylomastoid foramen (red arrow). Lateral semicircular conduct (discontinuous black arrow). Cochlea (dark green arrow) Fig. 10 Images for this section: Fig. 1: 1. Squamous portion 2. Petrous portion 3. Mastoid portion 4. Styloid portion Page 13 of 41 Fig. 2: 1. Malleus head 2. Malleus manubrium 3. Incus body 4. Incus long process 5. Stapes head 6. Anterior crura of stapes 7. Posterior crura of stapes 8. Epitympanum 9. Mesotympanum 10. Hypotympanum 11. External auditory canal Page 14 of 41 Fig. 3: 1. Squamous portion 2. Petrous portion3. Mastoid portion Fig. 4: Shows external auditory canal cartilaginous (EACc) and osseous (EACo) segments to the tympanic membrane (arrow) Page 15 of 41 Fig. 5: Head of malleus (yellow arrow)Short process of incus (red arrow), Prussak space (green arrow) Page 16 of 41 Fig. 6: Manubrium of malleus (yellow arrow), stapes (red arrow), long process and lenticular process of incus(blue arrow) Page 17 of 41 Fig. 7: Green line represents imaginary limit floor from scutum (3) to tympanic portion of facial nerve (1). Tegmen tympani (2) represents the roof. Fig. 8: Green lines represent imaginary limits for roof and floor of mesotympanum. Red line marks tympanic membrane. Page 18 of 41 Fig. 9: Internal auditory canal (IAC), cochlear foramen (black arrow), cochlea (red arrow), vestibule (pink arrow)semicircular posterior conduct (blue arrow), oval window (green arrow), mastoid sinus (*) Page 19 of 41 Fig. 10: Labyrinthine segment (light green arrow). Anterior genu (yellow arrow). Tympatic segment (pink arrow). Posterior genu (light blue arrow). Mastoid segment (black arrow) Stylomastoid foramen (red arrow). Lateral semicircular conduct (discontinuous black arrow). Cochlea (dark green arrow) Page 20 of 41 Imaging findings OR Procedure details TEMPORAL BONE FRACTURES: Ø The spectrum of temporal bone trauma is extremely wide, ranging from minor contussion without functional deficits to severe blunt or penetrating trauma with multifunctional deficits that involve the auditory and vestibular nerves, the facial nerve, and the intracranial contents. Ø Usually temporal bone fractures occur in politraumatic patients with serious vital problems (neurologic, thoracic, abdominal), so temporal bone fractures become into the background of urgency. Ø However there are some clinical and radiological signs which must make us think about temporal bone fracture: • • CLINIC SIGNS: Otoliquorrhea, hemotympanum, facial nerve paralysis, Battle's sign (ecchymosis of the postauricular skin), "Racoon eyes" (ecchymosis of the periorbital area) CT SIGNS: Opacification of the mastoid air cells on page or middle ear, unexplained pneumocephalus on page , gas within the temporomandibular joint on page , soft tissue swelling over the temporal region on page . All fracture lines are best identified on axial CT images. EPIDEMIOLOGY: Ø Head is the most frequently injured part of the body. Head injuries occur in approximately 75% of all motor vehicle accidents and temporal bone fractures are the most common fractures in the skull base. Ø 20% of patients with skull fracture have temporal bone fractures Ø 2.5% temporal bone fractures involve otic capsule Ø 10% associated with VII pair injury; 85% with geniculate ganglion CLASSIFICATION: depending on the direction of the fracture line 1. 2. 3. LONGITUDINAL: parallel to long axis of temporal bone TRANSVERSAL: perpendicular to long axis of temporal bone MIXED or OBLIQUE: combination of longitudinal and tranversal fractures 1. LONGITUDINAL FRACTURE: (Fig. 1 to 6) Ø Fracture line is parallel to long axis of petrous bone Ø Represents about 70-90% of total temporal bone fractures Ø Results by a lateral trauma at temporal or parietal region Page 21 of 41 Ø Typically crosses the external auditory canal through the middle ear, can involve the region of the geniculate ganglion and ends in the fibrous tissue of the foramen lacerum Ø Can be distinguished two subtypes depending on their origin: 1. 2. Anterior: involves squamos segment, tegment tympani, glenoid fossa and facial nerve Posterior: involves mastoid, ossicular chain and facial nerve Ø The most common course of the fracture is anterior and extralabyrinthine; however, although rare, intralabyrinthine extension is possible. Ø COMPLICATIONS: 1. 2. 3. 4. Conductive hearing loss (60%): due to ossicular dislocation (more often involves incudoestapedial joint) or fracture or laceration of the tympanic membrane Hemotympanum (>90%): sometimes is the only sign of fracture present Cerebrospinal fluid (CSF) otolyquorrhea (50%): caused by fracture of tympanic roof when the fracture line perforates the dura. Sometimes develop meningitis. Facial incomplete paralysis (rare) 2. TRANSVERSE FRACTURE: (Fig. 7a and 7b) Ø Fracture line is perpendicular to long axis of petrous bone Ø Approximately 20% of total temporal bone fractures Ø Results on a blow to the head at frontal or occipital region Ø Often involves otic capsule, internal auditory canal (IAC) and facial nerve canal Ø Usually respects external auditory canal (EAC) and middle ear Can be distinguished two subtypes depending on their relationship with arcuate eminence of petrous bone (a prominence on the anterior surface indicating the position of the superior semicircular canal): Ø 1. 2. st Medial subtype: posterior petrous surface through fundus of IAC to 1 genu of facial nerve Lateral subtype: posterior petrous surface through labyrinth Ø COMPLICATIONS: 1. 2. 3. 4. 5. 6. Sensorineural hearing loss or deafness: associated to medial subtype Perilymphatic fistula: common in lateral subtype Vestibular dysfunction: vertigo, balance disturbance Severe nystagmus Facial complete paralysis (30-50%) Vascular injuries: internal carotid artery or jugular vein Page 22 of 41 3. MIXED OR OBLIQUE FRACTURE: (Fig. 8 to 10) Ø Longitudinal and transverse fracture combined Ø Represents about 10% of total temporal bone fractures, but according to some authors, these patterns occur more often than isolated transverse or longitudinal fractures. Ø Associated to intracranial complications frequently Images linked within the text of this section: Fig.: Axial CT shows two air bubbles within right temporomandibular joint. Page 23 of 41 Fig.: Axial head CT shows the presence of soft issue outside temporal left bone (yellow arrow) and a bone fragment within external auditive conduct (red arrow) as a result of head trauma. Page 24 of 41 Fig.: Coronal CT bone demonstrates an intracranial air bubble in a politraumatic patient. Page 25 of 41 Fig.: Opacification of right mastoid cells (black arrow). Additional images for this section: Page 26 of 41 Fig. 1: Axial bone CT demonstrates fracture line extending along right mastoid process (black arrows), causing middle ear fluid (hemotympanum). Note the presence of middle cranial fossa pneumocephalus (yellow arrow). Page 27 of 41 Fig. 2: Axial CT reveals a longitudinal line of fracture at the roof of petrous bone, from mastoid air cells extending to middle ear. Page 28 of 41 Fig. 3: Axial CT shows longitudinal fracture line (anterior subtype) from mastoid surface to tympanic cavity (red arrow), hemotympanum, incudoestapedial joint disruption(yellow arrow) and mastoid cells opacification. Page 29 of 41 Fig. 4: Axial CT demonstrates fracture line in the anterior surface of mastoid cells (yellow arrow). Oppacification of mastoid air cells and middle ear. Malleoincudal joint disruption (red arrow). Page 30 of 41 Fig. 5: Sagital MPR of right temporal bone reveals a longitudinal fracture (yellow arrows) from the roof of petrous bone extending to temporomandibular joint.Opacification of middle ear without ossicular chain involvement. Malleus (red arrow), incus (green arrow). Page 31 of 41 Fig. 6: Can be visualizated two bilateral longitudinal anterior subtype lines of fracture (yellow arrows) from mastoid surface to petrous apex. Page 32 of 41 Fig. 7: Reveals bilateral longitudinal fracture lines from mastoid to apex petrous (yellow arrows). Black arrows indicates ossicular chains which are posterior to them. Page 33 of 41 Fig. 8: Axial CT scan of the right temporal bone reveals fracture line (arrow) extending from the edge of internal auditory canal to carotid canal. Page 34 of 41 Fig. 9: Axial CT scan of the right temporal bone reveals fracture line (arrow) extending from the edge of internal auditory across petrous apex. Page 35 of 41 Fig. 10: Axial CT demonstrates a severely comminuted fracture with extracranial fragment bones (black arrow) and opacification of mastoid cells and middle ear. Page 36 of 41 Fig. 11: Axial CT demonstrates a severely comminuted fracture with extracranial fragment bones (black arrow) and middle cranial fossa pneumocephalus (white arrow). Page 37 of 41 Fig. 12: Axial CT shows two different fracture lines. The first one (yellow arrow) has a longitudinal trajectory from mastoid to anterior segment of tympanic cavity, associated with hemotympanum and malleoincudal joint disruption. Also reveals a tranverse fracture line (medial subtype) extending from posterior surface of temporal bone to carotid canal (black arrow). Page 38 of 41 Fig. 13: Politraumatic patient who presents multiple fracture lines:The first one courses along parietal bone, crossing squamous portion of temporal bone to reach the roof of externe auditive conduct (red arrows).Also frontal and parietal fracture lines are demonstrated (black arrows). Page 39 of 41 Conclusion Petrous bone fractures must be taken into account in patients with cranial trauma because of their serious consequences and relatively high frecuency. It is important to recognize anatomic structures in order to make a correct diagnosis. Personal Information Silvia Rosa Calero, Mònica Larios Sánchez, Cristina Delgado Ricote, Diasol Villa Viñas, Tomás Sempere Durá Radiodiagnostic department Esther Domènech Vadillo Otorrinolaringology department Hospital Universitari Joan XXIII (Tarragona, Spain) References 1. Harnsberger H. R. Temporal bone anatomy and imaging issues. In Harnsberger et al. Diagnostic imaging: Head and neck. Amirsys Inc. 2nd Ed. Canada. P I-2-2, I-2-5 2. Swartz J. D. Temporal bone fractures. In Harnsberger et al. Diagnostic imaging: Head and neck. Amirsys Inc. 2nd Ed. Canada. P I-2-196, I-2-199 3. Fatterpekar GM, Doshi AH , Dugar M, Delman BN, Naidich TP, Som PM. Role of 3D CT in the evaluation of the temporal bone. Radiographics 2006; 26: S117-S132 4. Veillon F, Dosch JC, Dutreix JL, Stierle JL et Bloch P. Exploration radiologique des traumatismes de l'oreille. Oto-rhino-laryngologie, 20-047-A-50, 1988, 8p 5. Sempere Durá T. Atlas de anatomía por la imagen seccional [CD]. 2009 Química farmacéutica Bayer. S.L 6. Huey-Jen Lee, Cheemun Lum, Jeans K, Chandrasekhar S, Brown L, Holodny A. Temporal bone fractures and complications: correlation between high-resolution computed tomography and audiography. American Society of Emergency Radiology 1997; 5: 1070-3004/98/8-12 Page 40 of 41 7. Meriot P, Veillon F, García JF, Nonent M, Jezequel J, Bourjat P, Bellet M. CT appearances of ossicular injuries. Radiographics 1997; 17: 1445-1454 8. Lane JI, Lindell EP, Witte RJ, Delone DR, Driscoll CLW. Middle and inner ear: improved depiction with multiplanar reconstruction of volumetric CT data. Radiographics 2006; 26: 115-124 9. Grossman RI, Yousem DM. Neurorradiología. Ed. Marbán. Madrid 2007 10. Gaensler E. H. L. Neurorradiologia fundamental. Ed. Marbán. Madrid 1998 nd 11. Osborn A. G. Angiografía cerebral. 2 edition. Marbán. Madrid 2000. 12. Riera March A. et al. Temporal bone fractures. Updated 20 mar 2008. http://emedicine.medscape.com/ article/857365-overview 13. Valvassori G.E, Buckingham R.A., Carter B. L, Hanafee W. N, Mafee. M. F. Head and neck imaging. Thieme Inc. New York 1988 Page 41 of 41