Objectives Acoustic Neuroma:

definition, histopathology

Etiopathogenesis Classification Clinical Features Management

WHAT WILL ILEARN TODAY ?

FAQ’s in RGUHS

• Acoustic Neuroma• Clinical features of acoustic neuroma• Hitzelberger’s sign

Acoustic Neuroma• Definition:

Tumour of eighth cranial Nerve.

• Eponyms: Vestibular Schwannoma Neurilemmoma

• Incidence: 80% of Cerebellopontine angle tumours 10% of all brain tumours

Pathology

• Gross: Benign, Encapsulated, Slow-growing• Microscopy:Elongated spindle cells Rod-shaped nuclei in rows or palisades.

Origin & Growth

• Origin:Schwann Cells of Vestibular Nerve, rarely from cochlear nerve

• Growth: (slow) Causes widening and erosion of the canal and

appears in the CP angle Anterosuperior growth: 5th

Inferior: 9th , 10th & 11th Later stages: displacement of brainstem, pressure on

cerebellum and raised intracranial tension

Origin & Growth

Classification

Acoustic Neuroma

Intracellular Small Size <1.5cm

Medium size 1.5-4cm

Large Size > 4cm

Clinical Features• Age : 40-60 years• Sex: M=F• Symptoms: 1. Progressive unilateral SNHL2. Tinnitus3. Marked difficulty in understanding speech4. Imbalance/ Unsteadiness5. Vertigo6. Sudden Hearing loss7. Fullness in the ear

Cranial Nerve Involvement

1. 5th nerve: EARLIEST Reduced cornea sensitivity, paraesthesia of faceInvolvement indicates : tumour size = 2.5cm & occupies CP angle

2. 9th & 10th : dysphagia & hoarseness due to palatal, pharyngeal, laryngeal paralysis

3. Other cranial nerves: affected only when tumour size is very large

Cranial Nerve Involvement

Facial nerve:• Sensory fibres are affected early.• Hitzelberger’s sign : Hypoaesthesia of

posterior meatal wall• Loss of taste ( Electrogustometry)• Schirmer test : Reduced lacrimation• Motor fibres: Affected late• Delayed blink reflex

Brainstem Involvement

• Ataxia• Weakness & Numbness of arms and legs• Exaggerated tendon reflexes

Raised Intra-cranial tensionHeadache, nausea, vomiting, diplopia(6th) & papillo-edema with blurring of vision.

Cerebellar involvement

• Pressure symptoms on cerebellum are seen in large tumors

• Revealed by Finger-nose test Knee-heel test Dysdiadochokinesia Ataxic gait Inability to walk along a straight line (tendency to

fall on the affected side)

Investigations

• Audiological tests:1. PTA2. Speech Audiometry3. Recruitment

phenomena: Absent4. Short Increment

Sensitivity Index: 0-20% 5. Threshold tone decay

test : Retrocochlear type of lesion

Vestibular Tests

• Caloric test:

Diminished or absent response in 96% of patientsMay be normal when tumour is small

Neurological Tests

Complete examination of:• Cranial nerves• Cerebellar functions• Brainstem signs of pyramidal & sensory tracts• Fundus

Radiological tests

1. Plain X-ray:• Positive in 80% of patients• Different views:1. Transorbital2. Stenver’s3. Towne’s4. Submentovertical

2. Vertebral angiography:• Helps in differentiating AN from other tumours

Radiological Test

3. CT scan:• More sensitive than X-ray• Can detect even intra-meatal and posterior fossa tumors

4. MRI with Gadolinium contrast:• GOLD Standard• Can detect even intracanalicular tumours of few mm

Stapedial reflex Decay Test

Other tests

• BERA:A delay of >0.2ms in wave V between 2 ears in case of 8th nerve tumour

• CSF Examination:Protie level raised, Lumbar puncture should be avoided

Investigations

Important tests for AN work-up:• PTA• Speech discrimination score• Roll-over curve• Stapedial reflex decay• BERA• MRI with gadolinium contrast

Differential Diagnosis

• Meniere’s Disease• Tumours of CPangle:1. Meningioma2. Epidermoid3. Arachnoid Cyst4. Schwannoma of other cranial nerves5. Aneurysm6. Glomus tumour7. Metastasis

Treatment

Treatment

Surgical Radiotherapy

Surgical

• Treatment of Choice

Approaches

Middle Cranial Fossa Translabyrinthine Suboccipital

Combined translabyrinthine-

suboccipital

Radiotherapy

1. Conventional Radiotherapy2. X-knife/ɣ-knife surgery3. Cyber knife

X-knife/ɣ-knife surgery

• Stereotactic radiotherapy• Advantages:1. Minimal radiological effect 2. Causes reduction in tumour size &

growth.3. Can be used in patients where surgery is

not feasible.• Procedure : linear accelerator ɣ-knife through cobalt-60

RadiotherapyConventional:• Not prefered now due to low

tolerance of CNS to radiationCyber knife:• Modified X-knife• More accurate & frameless• Method: real-time image

guidance technology through computer controlled robotics.

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