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Lesions of and Surgical Approaches to the Petrous Apex 2.12.14 - Galloway - Denneny O Truncated pyramid O Medial to the inner ear labyrinth O Can be bisected by coronal plane through the IAC into the anterior and posterior petrous apex Pneumatization O Sclerotic O O Diploic O O 33% of patients Anterior petrous apex O O Middle ear Squamomastoid Petrous Apex Perilabyrinthine Accessory air cells Posterior petrous apex O O Air filled 5 general areas of pneumatization in the adult temporal bone O O O O O O Marrow filled Pneumatic O O Solid bone 10% of patients Not always symmetric O 4-7% of pneuatization is asymmetrical Pneumatization O Supralabyrinthi ne O Retrolabyrinthin e O Infralabyrinthine O Anterior labyrinthine The Petrous Apex O How do we find these lesions? O Are not amenable to direct clinical evaluation O Imaging O Symptoms which correlate with anatomic proximity to structures O What are these lesions? O What do we do with them? Differential to Lesions of the Petrous Apex O O O O O O O O O O O O O Asymmetric marrow Petrous apex effusion Petrous apex cephalocele Petrous apicitis Cholesterol granuloma Cholesteatoma Mucocele Skull base osteomyelitis Meningioma Chordoma Malignancies – metastasis, myeloma, chondrosarcoma Langerhans cell histiocytosis Endolymphatic sac tumor Asymmetric Marrow O Usually an incidental finding obtained for non-otologic complaints O Variable pneumatization of the petrous apex O O 4-7% of pneumatized apices are asymmetrical Marrow space should follow same signal characteristics as orbital fat on MRI T1 and T2 O O T1 and decrease in intensity with T2 Fat saturation should fully suppress the signal O CT should demonstrate a nonexpansile, nonaerated petrous apex O No further follow up is indicated O This may be misconstrued as a cholesterol granuloma Asymmetric Marrow O Leave me alone” lesions of the petrous apex AJNR Am J Neuroradiol 19:733-738. April 1998. O O 1989-1997 23 patients with “leave alone” lesions Asymmetric marrow or trapped fluid (effusions) Petrous Apex Effusion O Presumed to represent previous otitis media with subsequent obstruction of connections between middle ear and apical air cells. O Opacified air cells should demonstrate a high T2 signal – equivalent to CSF O The T1 signal may vary, depending on the protein content of the fluid O O Low T1 uncomplicated petrous air effusion Intermediate or high T1 CT scan to exclude an erosive or expansile lesion O O or possibly early cholesterol granuloma Lesions most likely to be misconstrued as cholesterol granuloma Petrous Apex Effusion Leave me alone” lesions of the petrous apex AJNR Am J Neuroradiol 19:733-738. April 1998. Petrous Apex Effusion Leave me alone” lesions of the petrous apex AJNR Am J Neuroradiol 19:733-738. April 1998. Petrous Apex Effusion Leave me alone” lesions of the petrous apex AJNR Am J Neuroradiol 19:733-738. April 1998. Petrous Apex Effusion Leave me alone” lesions of the petrous apex AJNR Am J Neuroradiol 19:733-738. April 1998. Petrous Apicitis O Complication of spread of infection of the mastoid and middle ear O In pre-antibiotic era this well known spread of otitis media with further intracranial complications O Guiesseppe Gradenigo described this classic triad of symptoms associated with petrous apicitis in 1907 Gradenigo’s Syndrome O Deep facial pain O Otitis media O Ipsilateral abducens palsy http://www.thebarrow.org/Education_And_Resources/Barrow_Quarterly/204927 http://www.thebarrow.org/Education_And_Resources/Barrow_Quarterly/204927 Petrous Apicitis O Current day symptomatology typically subtle O Previous mastoid surgery- complains of persistent infection and deep facial pain O Predominant organism O P. aeruginosa O Can also be considered central skull base osteomyelitis O If recalcitrant to antibiotics will require surgical drainage Petrous Apicitis O On MRI O T1- hypointense O T2 – hyperintense O Enhancing O On CT O Aggressive bony destruction O Consider gallium scan O Clinical evidence of infection http://synapse.koreamed.org/DOIx.php?id=10.3342/kjorl-hns.2009.52.3.279&vmode=PUBREADER#!po=16.6667 Petrous Apicitis Connor. Imaging of the petrous apex: a pictorial review. The British Journal of Radiology, 81 (2008) 427-435. Cholesterol Granuloma O Most common primary lesion of the petrous apex O 60% of all lesions in this area O May have silent presentation, O Expansile mass forms within isolated petrous apex air cells O Repetitive cycles of hemorrhage and granulomatous reaction granulomatous reaction initiated by obstruction of ventilation output O Brownish liquid with cholesterol crystals Cholesterol Granuloma O Imaging O MRI O High T1 O High T2 O Non-enhancing O CT O Bony moulding O Pressure deossification O Require Surgical drainage Connor. Imaging of the petrous apex: a pictorial review. The British Journal of Radiology, 81 (2008) 427-435. Cholesteatoma O Same as cholesteatoma elsewhere O Proliferation of skin – destructive keratinizing squamous epithelium O Congenital vs. Acquired (secondary) O Acquired O Erosion from the mastoid/middle ear O Otorrhea, facial nerve palsy, dizziness, hearing loss O Intracranial complication- meningitis, lateral sinus thrombosis, brain abscess Cholesteatoma O Congenital O Theories O Presence of epidermoid cells in middle ear during fetal development O Migration of the external meatus ectoderm O Less frequent than secondary cholesteatoma O Can develop for long period without symptoms O Sudden severe symptoms O i.e. facial nerve palsy (first symptom of congenital cholesteatoma), deafness Cholesteatoma O CT scan O Bony destruction O MRI O T1- low signal O T2- high intensity signal O Non-enhancing O Requires surgical excision Connor. Imaging of the petrous apex: a pictorial review. The British Journal of Radiology, 81 (2008) 427-435. Cumming’s Otolaryngology Chapter 135. Connor. Imaging of the petrous apex: a pictorial review. The British Journal of Radiology, 81 (2008) 427-435. Surgical Approaches to the Petrous Apex Julius Lempert O Father of modern otology O Jewish immigrant came to NYC in O O O O early 1900’s One of the three pioneers Glasscock dedicated his Surgery of the Ear book in the forward. First to use dental drills in lieu of chisels in mastoid surgery First to wear a headlight, instead of overhead lights Developed an approach to the petrous apex via the carotid artery which basis for modern skull base surgery O Approach through glenoid fossa http://www.michaeleglasscockiii.com/21/Julius_Lempert.htm Surgical Approaches O Classic approaches to posterior petrous apex O O O Anterior petrous apex O O O O O O Infracochlear Transotic approach Middle fossa approach Transcanal approach Endoscope assisted approach Image guidance approach – trans-sphenoidal O O O Transmastoid infralabrynthine approach Transmastoid translabrynthine approach Endonasal endoscopic Retrosigmoid approach Transpalatinal-transclival Surgical Approaches O Things to consider when choosing an approach O Serviceable hearing? O Drainage vs. Excision? O Where is your access/aircells? http://www.mayfieldclinic.com/PE-Acoustic.htm#.Uvr9axZ_hUQ Transmastoid procedures O Superior access for mass lesions such as cholesteatomas O Infralabryinthine approach can salvage hearing O Complete mastoidectomy with skeletonization of facial nerve O Locate infralabyrinthine air cell tract O Confirm this on preoperative imaging O Inferior to posterior semicircular canal, superior to jugular bulb, medial to facial nerve O Route passes inferior to IAC, through cochlear aqueduct (plug with bone wax to prevent CSF leak) O Translabryinthine approach Transcanal O Drainage of limited lesions of the anterior petrous apex O Elevate wide, superiorly based tympanomeatal flap, generous anterior and inferior canalplasty O Expose petrous carotid O Drill between cortical bone of the cochlea, internal carotid artery and follow air cell tract to anterior petrous apex. Endonasal Approaches O Open approaches to the skull base transphenoidally have been in practice since the 1980’s O Endoscopic Approaches O Medial approach O Medial approach with internal carotid artery lateralization O Transptyergoid infrapetrous approach O Choose your approach based on the proximity to the ICA, degree of pneumatizaiton of the sphenoid, medial expansion of lesion, pathology Endonasal Approach Utilization of landmarks Thank you