Acoustic Neuroma Summary

Key Facts:

Clinical Features:

Diagnosis:

Management Options:

Important: Chemotherapy is ineffective for acoustic neuromas

Acoustic Neuroma

Vestibular schwannoma - Diagnosis and Management

Acoustic neuroma (vestibular schwannoma) is a benign cerebellopontine angle tumour that grows from the superior vestibular component of the vestibulocochlear nerve, usually presenting with unilateral sensorineural hearing loss. Larger tumours can cause significant problems with cerebellar problems, increased intracranial pressure, and obstructive hydrocephalus, and, as a result, may be life threatening.

Risk Factors

A coexisting diagnosis of neurofibromatosis type 2 increases the prevalence of acoustic neuroma. This rare autosomal dominant disorder causes benign tumours on the vestibulocochlear nerves and other locations.

Clinical Features

Patients may have minimal symptoms, as tumours grow slowly. Signs and symptoms may not always correlate with tumour size.

Common symptoms

  • Unilateral sensorineural loss
  • Intermittent dizziness (caused by cerebellar compression or vestibular dysfunction)
  • Unilateral facial numbness (caused by compression of trigeminal nerve)
  • Tinnitus

Less common symptoms

  • Headache
  • Unilateral facial weakness
  • Altered tear production on affected side
  • Metallic or reduced taste on affected side
  • Diplopia on lateral gaze
  • Nystagmus
  • Swallowing difficulties
  • Loss of balance and coordination difficulties
  • Slower blink
  • Gait disturbance
  • Features of hydrocephalus or raised intracranial pressure

Investigations

Patients with unilateral hearing loss (especially if progressive) not responding to local ear care warrant referral for audiology testing, auditory brainstem reflexes and ENT consultation.

Gold Standard: All patients with sensorineural or retrocochlear findings on audiometry, especially if asymmetrical, are recommended for a gadolinium-enhanced MRI.

MRI Findings

  • Cerebellopontine angle lesion extending into the internal acoustic meatus
  • Absence of the dural tail is considered conclusive
  • Determines size and location of the tumour
  • Used to monitor tumour growth if resection is unsuitable

CT Scan

  • Less sensitive than MRI
  • May be used if MRI is unavailable
  • Can show bony changes in the internal auditory canal

Management

Patient management is influenced by local experience in focused radiation and surgical approach. Specific recommendations to patients, tumour size limits, and age and hearing level limits will vary greatly depending on local experience.

Observation

  • For smaller tumours with minimal symptoms
  • Serial scanning to monitor growth
  • Appropriate if no documented growth

Radiation Therapy

  • Stereotactic radiotherapy
  • Stereotactic radiosurgery
  • Preserves facial nerve function better than surgery in some cases

Surgical Options

  • Translabyrinthine approach
  • Retrosigmoid/suboccipital approach
  • Middle fossa approach
  • Choice depends on tumour size and hearing preservation goals

Note: Chemotherapy is ineffective for acoustic neuroma.