petrous apex final

04/11/23 ORLHNS-AFMC 1

Approaches to the petrous Apex

Presented by- Maj Pravin Singh

Moderator-Surg Capt R K Verma


Overview

• Introduction

• Anatomy of the petrous apex

• Lesions of the petrous apex

• Pre-op evaluation

• Surgical approaches

• Complications

• Recent advances


Introduction


Anatomy


• Cell Tracts• The infralabyrinthine

tract • The posteromedial tract

• The subarcuate tract • The anterior tract • The superior tract


Triangles of the Middle fossa• Anteromedial (Mullan's)

Triangle

• Anterolateral Triangle

• Posterolateral (Glasscock's) Triangle

• Posteromedial (Kawase's) Triangle

• Inferolateral Triangle

• Inferomedial Triangle


Lesions of the petrous apex

• Cystic Lesions-• Vascular

» Internal Carotid Aneurysm

» Venous Lake

• Nonvascular» Apicitis(abscess)

» Congenital epidermoid

» Cholesterol Granuloma

» Arachanoid Cyst

• Solid Lesions-• Benign

» Chondroma

» Neurofibroma

» Meningioma

» Paraganglioma

• Malignant» Chondrosarcoma

» Eosinophilic Granuloma

» Lymphoma

» Metastatic


• Cholesterol Granuloma• Most common cystic lesions of petrous apex• Also called

» Epidermoid cysts» Giant cholesterol cysts» Mucosal cysts

• Not true cysts-no epithelial lining• Result of Foreign Body reaction to cholesterol crystals• Pathogenesis-

– haemorrhage blood breakdown cholesterol release Giant cell FB reaction


• Cholesteatoma• Congenital-epidermoid cysts• Retention of epithelial remanants in the region of foramen

lacerum• Secondary – from middle ear• Spread via pre existing cell tracts• Slowly expanding lesion that progressively erodes the bone

of petrous apex


• Mucocele• Slowly expanding cystic lesion

• Formed by obstruction of mucous lines space containing glandular tissue

• Common in PNS

• rarely in pneumatized petrous apex


• Petrous apicitis-• Suppurative infection• Bacteriology-

» Pneumococcus

» H. Influenza

» B-haemolytic Streptococcus

» Staphylococcus sp.

» Pseudomonas sp

• Acute/ Chronic• Spread of infection into

pneumatized apex.

• Gradenigo Syndrome-» Diplopa

» Otorrhea

» Retro-orbital pain

• Complications-» Brain abscess

» Subdural empyema

» Meningitis

» Dural sinus thrombosis

• Management


• Skull Base Osteomyelits• extension of bacterial infection from otitis externa• Diabetic, immunocompromised• Clinically

» Deep pain» Refractory Otitis Externa

• Common pathogen –Pseudomonas• Management

» Appropriate antibiotic» Surgical if evidence of abcess, bony sequestra,

necrotic tissue


• Chondrosarcoma-• Slow growing• Primary malignancy of

bone• 5 histologic types

» Conventional» Myxoid» Mesenchymal» Clear cell» dedifferentiated

• Grossly gray,avascular, gelatinous,

• Surgical excision cornerstone of treatment


• Chondroma-• Rare• Locally aggressive• Midline lesions• Arise from embryologic

remanants of lnotocord• Grossly-

» Gelatinous, gray, avascular

• Histologcally-» Vacuolated

physaliporous cells within myxod matrix

» Lobulated, cords/ pseudoacini


• Meningioma• Arise from arachanoid villi of the meninges• Petroclival meningiomas from petroclival synchondrosis

• Neurogenic tumours• Schwannomas or Neuromas arising from adjacent cranial

nerves

• Metastatic lesions• Commonly from breast, lung, prostate, melanoma, kidney


• Intrapetrous Carotid Aneurysm• Rare• Congenital, • Acquired-traumatic, mycotic, Inflammatory• Angiography confirms diagnosis

• Osteodystrophy• Rare• Fibrous dysplasia, Paget`s disease, osteopetrosis• Hearing loss• Surgical decompression improves hearing


Clinical Presentation

• Hearing loss- most common• Vestibular dysfunction• Headache• Tinnitus• Facial spasm• Diplopia• Facial paralysis• Otorrhea

( Muckle RP, De la Cruz A, Lo WM. Petrous lesions. AM J Otol 1998;19:219-25 )


Imaging

• CT

• MRI

• Angiography-• Conventional• MRA• MR Venography• CT Angiography/ Venography


Approaches

• Hearing preserving– Infracochlear approach– Infralabyrinthine Approach– Middle Fossa Approach– Transsphenoidal Approach

• Non hearing preserving– Translabyrinthine Approach– Transotic approach– Subtotal Petrosectomy


Infracochlear approach

• Advantages• Hearing preserved• Preservation of normal

middle ear mechanism• Dependant drainage• Adequate access to

petrous apex despite high jugular bulb

• Disadvantages• Damage to facial nerve• Intimate knowledge of

the anatomy required


• Incision• Standard postaural

• Steps• Musculoperiosteal flap

raised• Meatotomy done• Canal incision at 2 and

10 o`clock given• Tympanomeatal flap

raised


• Inf bony annulus and floor of EAC drilled

• Hypotympanic and infra cochlear air cells exposed

• Chorda Tympani & Facial nerve Identified

• Landmarks-• The cochlea• The jugular bulb• The carotid artery


• Landmarks delineated• Infracochlear air cells

removed• Air cell tract followed

to the petrous apex• Cyst wall opened and

contents evacuated


• Drainage silastic tube placed

• Bony defect repaired• TM flap repositioned• EAC packed• Wound closed in

layers• Mastoid dressing

applied


Infralabyrinthine Approach

• Advantages-• Familiar anatomy• Preservation of normal

middle ear mechanism• Preservation of hearing

• Disadvantages-• Access limited in high

jugular bulb• Larger lesions cannot

be excised


• Incision-• Standard Postaural

• Steps-• Musculoperiosteal flap

raised• Cortical mastoidectomy

done• Vertical portion of facial

nerve identified


• Sigmoid sinus and posterior semicircular canal skeletonized

• Jugular bulb identified

• Bill`s island left

• Infalabyrinthine air cell tract followed


• Petrous apex reached• Cyst wall exposed• Opened and drained• Silastic catheter

placed• Wound closed in

layers• Mastoid dressing


Translabyrinthine Approach

• Reintroduced by Hitselberger and House

• Advantages-• Greater exposure

• Drains cysts directly into the bony eustachian tube

• Disadvantages-• Sacrifice hearing

• Drainage not dependant

• Higher rate of CSF leak


• Incision-• Postaural C-shaped


raised• Cortcal mastoidectomy

done• Posterior fossa dural

plate, sigmoid sinus, sinudural angle, antrum and diagatric ridge exposed


• Vertical portion of facial nerve identified

• Facial recess opened and incus removed

• 3 semicircular canals systematically removed

• jugular bulb defined• IAC delineated


• Bone removed superior and inferior to IAC

• Petrous apex reached

• Lesion excised/ drained

• Cavity obliterated

• Wound closed in layers

• Mastoid dressing applied


Transotic/ Transcochlear approach

• Extension of translabyrinthine approach

• Introduced by Fisch • Advantage-

• Greater exposure• Reduced risk of CSF

leak

• Disadvantage-• Sacrifice hearing• Facial nerve injury


• Incision-• Postaural c-shaped


raised• Meatotomy done• Canalwall down

mastoidectomy done• Internal auditory canal

skeletonised


• Stapes extracted from oval window

• Cochlea removed• Limits of dissection-

• Facial nerve• Jugular bulb• Internal carotid artery

• Disease extracted• Eustachian tube

obliterated• Cavity obliterated• Wound closed in layers• Mastoid dressing applied


Middle Fossa Approach

• 1904 - Parry

• 1961 - William House

• Advantages-• Greater exposure• Preserves hearing• Exposes facial nerve

• Disadvantages-• Temporal lobe retraction• Risk of CSF fistula


• Position• Supine• Ear facing upwards

• Incision• Vertical• 5-6 cm• 1cm ant to tragus• Superiorly from

zygomatic arch


• Steps-• Fascia and

temporalis muscle split

• Retracted • Square bone flap

3cmm x 3cm• Upper limit-

squamous suture• One third post and

two third ant to EAC


• Temporal lobe elevated

• Foramen spinosum, arcuate eminance exposed

• GSPN identifed• Traced to geniculate

ganglion


• Kawase triangle Identified• GSPN preserved/

resected• Bone removed ant to

cochlea• Lesion exposed • Drainage/excision• Stenting• Closure• Pressure dressing


Transsphenoidal Approach

• Large cysts in proximity to post wall

• Advantages-• Preservation of hearing

• Disadvantage-• Increased risk to carotid artery• Risk of damage to the the optic nerve


• Steps• Posterior wall of

sphenoid sinus exposed

• Endospic assistance can be taken

• Cruciate incision made on post sphenoid wall

• Mucoperiosteal flap raised

• Small sphenoidotomy done


• The orifice enlarged using pituitary rongeurs

• Cystic lesion exposed

• Cyst wall opened

• Contents drained

• Nasal cavity packed, spheoid not packed


Subtotal Petrosectomy

• Described by Fisch and Mattox

• Advantage-• Full exposure of petrous apex

• Disadvantage-• Hearing is sacrificed


• Incision• Post aural C-shaped

• Steps• Musculoperiosteal flap

raised• Meatotomy done• EAC everted & sutured• Canal wall down

mastoidectomy done


• Remaining EAC skin, Tympanic membrane and annulus removed

• Air cells removed• Bony Labyrinth and

Cochlea removed• Lesion visualized and

removed• Remaining middle ear

mucosa removed


• ET obliterated• Cavity obliterated• Temporalis muscle

flap rotated inferiorly & sutured

• Wound closed in layers

• Mastoid dressing applied


Complications

• Hearing loss• Cranial Nerve Deficits

• III, IV, V, VI , VII

• Central Nervous System Sequelae• Injury to temporal lobe• Brain abscess• Meningitis• CSF leaks

• Vascular Injury• Jugular bulb• Extradural venous bleed

• Problems related to the wound


Recent Advances

• Image guided surgery


• Robotic Surgery


Bibliography

• Scott Brown , 7th Edition• Brackmann; Otologic Surgery 3rd Edition• Shambaugh; Surgery of the ear 6th Edition• Jackler; Neurotology• Eugene Myers; Operative Otolaryngology• OCNA; 2007, Vol 40, Issue3, Neurotology• Greenberg`s textbook of neurosurgery• Google Search

petrous apex final

Documents