Acoustic neuroma

Question 1

Definition

Answer 1

AKA - Vestibular schwannomas
Benign tumours of CN VIII arising from Schwann cells in the nerve sheath of the vestibular branch

Question 2

Pathophysiology

Answer 2

AN’s account for ~ 90% of cerebellopontine angle tumours.
- Often asymptomatic as their slow growth allows the surrounding tissue to stretch and accommodate them.
- Tumours in the internal auditory canal , produce symptoms much earlier
- Most acoustic neuromas are sporadic (95%) and unilateral.

Question 3

Epidemiology and Risk factors

Answer 3

• Aged 45-50 years
• Neurofibromatosis type 2: rare autosomal dominant genetic disease = typically bilateral and have an earlier age of onset ~ 30 years
• High-dose ionising radiation
• Caucasian ethnicity:
• Female sex

Question 4

Signs

Answer 4

Very few signs unless large tumours:
- Ataxia
- Co-ordination difficulties
- Nystagmus e.g. on lateral gaze
- Signs of increased ICP

Question 5

Symptoms

Answer 5

CN VIII :
- Unilateral, sensorineural hearing loss: progressive, but rarely sudden onset
- Unilateral tinnitus
- Progressive dizziness: balance issues subtle at presentation
Other Sx with large tumours = compression on surrounding CN
- CN 5: facial pain or numbness
- CN 7: facial palsy

Question 6

Diagnosis

Answer 6

• Urgent referral to ENT
  FIRST LINE: Audiological testing: Asymmetrical sensorineural hearing loss on audiological testing = go onto have MRI. Audiogram abnormal >90% of Px
  GOLD STANDRD: Gadolinium-enhanced MRI = appears as a cerebellopontine angle lesion extending into the internal acoustic meatus

Question 7

Treatment Options

Answer 7

Observation
Surgery
Radiotherapy

Question 8

Observation

Answer 8

Watch and wait : For smaller tumours in ASx Px, esp in older patients. Px are monitored with interval MRI scans annually for the first 5 years.
- If there is evidence of growth on interval scanning, interventional treatment is recommended

Question 9

Sterotactic surgery/treatment

Answer 9

Used to administer a focused, strong dose of radiation to the tumour
- Stereotactic radiosurgery = single treatment
- Stereotactic radiotherapy = administered in smaller doses over multiple treatments
- Radiotherapy may provide similar levels of tumour control, and better levels of hearing and facial nerve preservation, compared to surgical approaches

Question 10

Surgical removal

Answer 10

FIRST LINE = Tumours >3cm in size due to their potential for life - threatening mass effects

Question 11

Complications from large tumours

Answer 11

• Trigeminal and facial neuropathies
• Brainstem compression
• Hydrocephalus

Question 12

Complications from surgery/radiotherapy

Answer 12

• Hearing loss
• Facial weakness
• CSF leak