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Health condition · Clinically reviewed

Acoustic neuroma, observation, Gamma Knife or skull-base surgery.

A benign but eloquent tumour on the hearing and balance nerve. The right pathway depends on size, symptoms and age.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, ENT UK, British Skull Base Society and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including MRI surveillance, Gamma Knife radiosurgery and skull-base microsurgery.

Key facts

Acoustic neuroma at a glance.

The essentials, in plain English - what it is, how it presents, and the three pathways UK skull-base teams use.

  • What it is

    A benign Schwann cell tumour of the vestibular nerve, growing in the internal auditory canal or cerebellopontine angle.

  • How common

    Around 1 in 100,000 per year in the UK. Around 90% are unilateral and sporadic.

  • Bilateral

    Bilateral vestibular schwannomas are pathognomonic for neurofibromatosis type 2 (NF2) and need genetics input.

  • Classic triad

    Asymmetric sensorineural hearing loss, one-sided tinnitus and imbalance are the hallmark presenting features.

  • Gold-standard test

    MRI internal auditory meati with gadolinium is the diagnostic gold standard.

  • Three pathways

    Observation with serial MRI, stereotactic radiosurgery, or microsurgery via a skull-base team.

Why this guide matters

One diagnosis, three very different pathways.

Acoustic neuroma is benign, but it sits on the hearing and balance nerve next to the facial nerve and brainstem. The choice between observation, radiosurgery and microsurgery matters.

  • Watchful waiting is legitimate

    Around half of small tumours do not grow. Serial MRI is the safest starting point for many patients, especially over 60.

  • Radiosurgery is highly effective

    Gamma Knife controls more than 95% of small and medium tumours at 10 years with good facial nerve preservation.

  • Surgery is decisive for large tumours

    Skull-base microsurgery remains the answer for large or brainstem-compressing tumours, and for many younger patients.

How the diagnosis is made

From asymmetric hearing loss to a clear plan.

The steps a UK ENT team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and examination

    Timing of hearing change, tinnitus, vertigo, imbalance and any facial numbness or weakness. Cranial nerves V, VII and VIII are checked carefully.

  2. 02

    Assessing

    Pure-tone audiometry

    The first line test. Asymmetric high-frequency sensorineural loss is the classic pattern that triggers imaging.

  3. 03

    Assessing

    Speech discrimination

    Word recognition is often disproportionately poor on the affected side, a soft sign of retrocochlear pathology.

  4. 04

    Confirming

    MRI IAMs with gadolinium

    The gold standard. Shows the tumour location and size and separates intracanalicular, canalicular-cisternal and brainstem-compressing disease.

  5. 05

    Confirming

    Auditory brainstem response

    Used selectively where MRI is contraindicated or as an adjunct. A prolonged wave V latency is suggestive.

  6. 06

    Confirming

    Facial nerve assessment

    House-Brackmann grading of any weakness. Facial function is a key outcome measure across all three treatment pathways.

  7. 07

    Planning

    Skull-base MDT referral

    A joint neuro-otology and neurosurgery clinic decides on observation, radiosurgery or microsurgery, with genetics input if bilateral disease.

Typical timeline: audiometry, MRI and MDT decision within a few weeks.

Symptoms

What acoustic neuroma actually feels like.

A slow, one-sided cluster of hearing, tinnitus and balance symptoms - occasionally with facial or brainstem features when the tumour is larger.

  • Asymmetric hearing loss

    Gradual, one-sided sensorineural hearing loss is the commonest presenting feature and the strongest single red flag.

  • Unilateral tinnitus

    A persistent ringing or hissing in one ear, often noticed before the hearing change itself.

  • Imbalance and vertigo

    Vague unsteadiness is more typical than true spinning vertigo. The vestibular system compensates slowly.

  • Facial numbness

    Trigeminal (V) involvement suggests a larger tumour reaching the cerebellopontine angle.

  • Facial weakness

    Uncommon at presentation but a warning sign. Any true facial nerve palsy warrants urgent imaging.

  • Headache

    Occipital or generalised headache can appear as tumours enlarge, particularly with brainstem contact.

  • Brainstem compression

    Large tumours can cause ataxia, dysphagia or hydrocephalus. These are indications for urgent surgical review.

  • Red flag - sudden hearing loss

    Sudden sensorineural hearing loss needs same-week ENT assessment and MRI to exclude a vestibular schwannoma.

Treatment

How acoustic neuroma is treated in the UK.

Observation for many small tumours, Gamma Knife or CyberKnife radiosurgery for small and medium tumours, skull-base microsurgery for larger ones - and specialist NF2 care where relevant.

  • Watchful waiting

    For small, asymptomatic tumours - especially in older patients. Around half of small tumours do not grow on serial MRI.

  • Serial MRI surveillance

    Annual gadolinium-enhanced MRI, then extended intervals if stable. Growth of more than 2 mm per year prompts a rethink.

  • Gamma Knife radiosurgery

    A single-session focused radiation option for tumours under 2.5 to 3 cm. Tumour control exceeds 95% at 10 years.

  • CyberKnife radiosurgery

    A frameless robotic alternative to Gamma Knife, sometimes delivered in a small number of fractions.

  • Translabyrinthine microsurgery

    A skull-base approach that sacrifices any residual hearing but gives excellent facial nerve access for larger tumours.

  • Retrosigmoid microsurgery

    A posterior fossa approach that can preserve hearing in selected cases. Used for medium and large tumours.

  • Middle fossa microsurgery

    Reserved for small intracanalicular tumours where hearing preservation is the priority.

  • NF2-specific care

    Bilateral vestibular schwannomas need a specialist NF2 service. Bevacizumab can slow growth and preserve hearing.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your ENT surgeon or skull-base team knows the imaging and hearing tests and can tell you which pathway fits you. If in doubt, ask.

  • ENT UK. Guidelines on the management of vestibular schwannoma.

  • British Skull Base Society. Consensus on vestibular schwannoma pathways.

  • NICE. Sudden onset hearing loss - suspected acoustic neuroma referral criteria.

  • Manchester NF2 Service. National standards for NF2 care in England.

Red flags

When acoustic neuroma needs urgent attention.

Most cases move at a slow, planned pace. These are the situations where the pace has to change.

  • Sudden sensorineural hearing loss

    Sudden one-sided hearing loss needs same-week ENT assessment. Around 1 in 20 cases turn out to be a vestibular schwannoma.

  • Facial nerve palsy

    True facial weakness is unusual and points to a larger tumour or an alternative diagnosis. Urgent imaging is warranted.

  • Rapid tumour growth

    Growth of more than 2 mm per year on serial MRI usually prompts a move from observation to active treatment.

  • Bilateral vestibular schwannomas

    Diagnostic of NF2 until proven otherwise. Needs referral to a specialist NF2 service and genetic testing.

  • Brainstem compression

    Ataxia, dysphagia, cranial nerve palsies or hydrocephalus need urgent neurosurgical review.

  • New severe headache

    Worsening occipital headache, morning vomiting or visual change may signal hydrocephalus.

  • Post-radiosurgery swelling

    Transient tumour enlargement is common in the first 12 to 18 months. Sudden new symptoms still need review.

  • Persistent CSF leak after surgery

    Clear watery discharge from the nose, ear or wound after skull-base surgery needs urgent assessment.

  • Progressive imbalance

    A meaningful drop in day-to-day function is an indication to reconsider active treatment.

Living with it

A benign tumour, managed for the long term.

Four things that make the biggest difference day to day - staying with your MRI plan, rehabilitating the hearing loss, retraining balance and protecting the facial nerve and eye.

A quiet reminder

Consistency beats intensity, every time.

Small, steady habits - kept up for months - do more than a heroic week that does not last.

  1. 01 Monitor

    Stick to your MRI schedule

    Serial imaging is how observation stays safe. Do not skip the annual or two-yearly scan even if you feel well.

  2. 02 Hearing

    Rehab the hearing loss

    Hearing aids, CROS aids, bone-anchored devices and, in selected cases, cochlear implants all have a role after treatment.

  3. 03 Balance

    Vestibular rehabilitation

    Structured balance therapy accelerates central compensation after both surgery and radiosurgery.

  4. 04 Face

    Facial nerve care

    Eye lubrication, facial physiotherapy and, where needed, oculoplastic input protect the eye and support recovery.

Frequently asked

Everything we get asked about acoustic neuroma.

Quick answers on diagnosis, observation, radiosurgery, microsurgery and NF2.

  • What is an acoustic neuroma?

    An acoustic neuroma - properly called a vestibular schwannoma - is a benign tumour arising from the Schwann cells of the vestibular part of the eighth cranial nerve. It grows slowly in the internal auditory canal or cerebellopontine angle and does not spread elsewhere.

  • How is it diagnosed?

    The classic path is audiometry showing asymmetric sensorineural hearing loss, followed by an MRI of the internal auditory meati with gadolinium contrast. MRI is the diagnostic gold standard and shows the size, location and any brainstem contact.

  • Do I need treatment straight away?

    Not always. Small, asymptomatic tumours can be watched with serial MRI, and around half of small tumours do not grow. Active treatment is offered when the tumour grows, causes troublesome symptoms or is already large at diagnosis.

  • What is Gamma Knife radiosurgery?

    Gamma Knife is a single-session focused radiation treatment delivered without an incision. It is the preferred non-surgical option for tumours under about 2.5 to 3 cm, with tumour control rates above 95% at 10 years and good hearing and facial nerve preservation.

  • When is microsurgery needed?

    Microsurgery is offered for larger tumours, those pressing on the brainstem, or younger patients with a long life expectancy who prefer definitive removal. The translabyrinthine, retrosigmoid and middle fossa approaches are chosen based on tumour size and hearing status.

  • What is different about NF2?

    Bilateral vestibular schwannomas define neurofibromatosis type 2. Management is coordinated by a specialist NF2 service and often includes bevacizumab to slow growth, hearing preservation strategies and planned surveillance of other schwannomas and meningiomas.

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