Acoustic Neuroma & Glomus Tympanicum Dr. Vishal Sharma

Acoustic Neuroma

Introduction A.K.A.: vestibular schwannoma / neurilemmoma Benign, encapsulated, slow growing tumour arising from Schwann cells of superior vestibular division of 8th nerve within internal auditory canal Rarely from inferior vestibular or cochlear division

Tumour growth Tumor expansion within internal auditory canal  causes widening & erosion of I.A.C.  appears in cerebello-pontine angle (> 2.5 cm)  involves 5th, 7th, 9th, 10th, 11th cranial nerves  displacement of brainstem & cerebellum  raised intracranial pressure  Involvement of 6th & 3rd cranial nerves

Classification as per size 1. Intra-canalicular: confined to I.A.C. 2. Small: up to 1.5 cm 3. Medium: 1.5 to 4 cm 4. Large: over 4 cm

Tumor size

Intra-canalicular

Small

Medium

Large

Epidemiology 10% of all brain tumors 80% of all Cerebello-pontine angle tumors Age: 40-60 yrs Male : Female = 3:2 Unilateral (90%); Bilateral (10%) Bilateral = von Recklinghausen’s neurofibromatosis

Clinical Staging Otological stage: due to pressure on 8th nerve Other Cranial nerve involvement Brainstem + Cerebellar involvement Raised intra-cranial tension Terminal stage: failure of vital centers of brainstem & cerebellar tonsil herniation

Otological symptoms & signs Progressive, unilateral sensorineural deafness Poor speech discrimination (disproportionate) Tinnitus Mild vertigo Nystagmus Vestibular symptoms appear late due to slow tumor growth & vestibular compensation

Other Cranial nerve palsy Trigeminal: first nerve to be involved Loss of corneal reflex Pain, numbness and paresthesia of the face Facial: Hypoaesthesia of posterior external auditory canal wall (Hitselberger’s sign) Facial weakness, Loss of taste, ed lacrimation

Other Cranial nerve palsy Glossopharyngeal, Vagus & Accessory Spinal: Dysphagia Hoarseness Nasal regurgitation Decreased gag reflex Abducent & Oculomotor: Diplopia

Brainstem involvement  Ataxia  Weakness of arms & legs  Tendon reflexes exaggerated Cerebellar involvement  Ataxic gait (fall on affected side)  Intention tremors  Past-pointing  Dysdiadochokinesia Increased Intra-cranial tension  Headache  Projectile vomiting  Blurred vision  Papillodema  Abducent nerve palsy

First Symptoms Hearing loss: 80-100 % Vertigo: 10-50 % Tinnitus: 5-10 % Ear ache: 5 % Sudden hearing loss: 5% Facial paralysis: 1-2 %

Investigations Pure Tone Audiometry: high frequency SNHL Speech audiometry: SD scores < 30% Tone decay test: positive Stapedial Reflex: Decay > 50 % in 10 sec B.E.R.A.: wave V >4.2 ms; inter-wave V >0.2 ms Caloric test: I/L canal paresis or no response C.T. scan with contrast: for tumor > 0.5 cm M.R.I. with gadolinium contrast: best

Pure Tone Audiogram

Speech Audiometry Roll over phenomenon

Calorigram

Brainstem Evoked Response Audiometry (B.E.R.A.)

Contrast C.T. Scan

Contrast M.R.I.: neuro-anatomy

Contrast M.R.I. : intra-canalicular

Contrast M.R.I. : small

Contrast M.R.I. : Medium

Contrast M.R.I. : Large

Bilateral tumor: small

Bilateral tumor: large

Treatment 1. Observation 2. Microsurgical removal: (partial or total) Trans-labyrinthine approach Retro-sigmoid or Sub-occipital approach Middle Cranial Fossa approach Combined approach 3. Proton Stereotactic Radiotherapy 4. Brainstem Implant: after B/L tumor excision

Observation Indications: Age > 60 years with small tumor & no symptoms Tumour in only hearing / better hearing ear Serial MRI used to follow growth pattern. Treatment recommended if hearing is lost or tumor size becomes life threatening.

House Ear Institute 1977

Incisions Middle cranial fossa Retro-sigmoid Trans-labyrinthine

Retro-sigmoid Approach

Sub-occipital approach

Trans-labyrinthine approach

Middle cranial fossa approach

Surgical Approach Protocol 1. Intra-canalicular: Middle cranial fossa approach 2. Small (<1.5 cm): Retrosigmoid approach 3. Medium (1.5 - 4 cm) a. Hearing fine**: Retrosigmoid approach b. Hearing bad: Trans-labyrinthine approach 4. Large (>4 cm): Trans-labyrinthine / Combined ** Pure Tone Average < 30 dB, S.D. Score >70%

Intra-operative photograph

Proton stereotactic radiotherapy Single high dose of radiation delivered on a small area to arrest or kill tumor cells. Minimal injury to surrounding nerves & brain tissue Gamma Knife: radioactive cobalt LINAC X-knife: linear accelerator Cyber-Knife: robotic radio-surgery system Indication: 1. Surgery refused / contraindicated 2. Post-operative residual tumour

Treatment Planning

Treatment Planning

P.S.R.T. in progress

Pre & Post treatment

Glomus Tumours

Introduction Synonym:  Chemodectoma  Non-chromaffin paraganglioma Commonest benign tumour of middle ear derived from glomus bodies distributed along parasympathetic nerves of head & neck Consists of paraganglionic cells derived from embryonic neuroepithelium

Introduction Histologically benign but locally invasive, highly vascular, non-encapsulated, slow growing tumors 10 % tumors: familial 10 % tumors: multicentric 10 % tumors: functional (secrete catecholamines) 4 % tumors: metastatic

Histopathology Typical cellular groups ("Zellballen") surrounded by a capillary network

Types Glomus jugulare Arises along jugular bulb & superior vagal Ganglion, near floor of middle ear Glomus tympanicum Arises along tympanic plexus on promontory formed by tympanic branch of Glossopharyngeal nerve, near medial wall of middle ear

Spread

Common Symptoms Seen in 40-60 yrs Female : male = 5:1 U/L deafness: progressive, conductive Pulsatile tinnitus: synchronous with pulse decreases on carotid occlusion Blood stained otorrhoea Ear ache & vertigo: rare

Signs Rising sun sign: red reflex on otoscopy Browne’s pulsation sign on siegalization: Positive pressure  tumor engorges  tumor blanches  pressure released  tumor engorges Aural mass: bleeds on touch Systolic bruit: over mastoid on auscultation Neurological: 9th, 10th 11th cranial nerve palsy

Rising sun sign

Blood-stained otorrhoea

Bleeding polyp

Investigations 1. Pure Tone Audiometry: Conductive deafness 2. High resolution C.T. scan with contrast: erosion of carotico-jugular spine (Phelp’s sign) 3. Magnetic Resonance Imaging with Gadolinium contrast: for soft tissue & intra-cranial extension 4. M. R. Angiography: non-invasive. For invasion of Internal jugular vein & internal carotid compression

Investigations 5. Digital Subtraction Angiography 6. Four Vessel Angiography  Tumour blush  Feeding arteries  Contra lateral circulation  Embolization (within 48 hours of surgery)  Other carotid body tumors

Investigations 7. 24 hour urine Vanillyl Mandelic Acid level: > 7 mg  Catecholamine secreting tumor  Initial hypertension during surgery followed by hypotension 8. Careful biopsy of mass in ext. auditory canal: rule out malignancy. Ear packing done for profuse bleeding.

C.T. scan plain Glomus Jugulare

Plain & contrast C.T. scan

M.R.I. with contrast

4 Vessel Angiography

Digital Subtraction Angiography

Pre & Post embolization

Magnetic Resonance Angiography

Fisch Staging Stage A: tumor limited to middle ear cleft Stage B: tympano-mastoid tumor sparing infra-labyrinthine bone Stage C: tympano-mastoid tumor eroding Stage D1: Intra-cranial extension < 2 cm Stage D2: Intra-cranial extension > 2 cm

Surgical Treatment Anterior Tympanotomy: small stage A Extended facial recess approach: large stage A Modified Radical Mastoidectomy: small Stage B Combined Modified Radical Mastoidectomy + Fisch’s Infratemporal fossa approach: large stage B, Stage C Subtotal temporal bone resection: Stage D1

Anterior Tympanotomy

Infratemporal fossa approach

Facial nerve decompression

Facial nerve re-routing

Tumor excised

Other Treatments Tele - Radiotherapy (4000 – 5000 rads) or Stereotactic Radiotherapy: Inoperable, residual or recurrent tumors; Pt unfit for surgery or refuses surgery Observation: Pt > 70 yr with minimal symptoms Embolization: Before surgery: reduces vascularity After RT: for residual or recurrent tumor

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