Acoustic Neuroma / Vestibular Schwannoma Surgery

Introduction

An acoustic neuroma — also called a vestibular schwannoma — is a benign (non-cancerous) tumour that grows on the nerve connecting the inner ear to the brain. It usually grows slowly. Even though it is not a cancer, it sits in a delicate area near the brainstem and several important nerves, so when it grows large enough to cause symptoms, doctors often recommend treatment.

This article is written for patients who have already been diagnosed with an acoustic neuroma and are considering or preparing for surgery, as well as those who have had surgery and want to understand recovery and long-term follow-up. It explains what the surgery involves, the different surgical approaches, the non-surgical alternatives, the risks to hearing and facial nerve function that come with this kind of operation, and what life tends to look like in the months and years afterwards.

Decisions about acoustic neuroma management are highly individual. Tumour size, location, hearing level in both ears, your age and general health, and the experience of the treating team all matter. The information here is intended to help you have a more informed conversation with your surgical team, not to replace it.

What Is Acoustic Neuroma Surgery?

Acoustic neuroma surgery is a neurosurgical operation to remove a vestibular schwannoma. The tumour grows from the Schwann cells that wrap and insulate the vestibulocochlear nerve — the eighth cranial nerve — which carries hearing and balance signals from the inner ear to the brain. Most acoustic neuromas arise on the vestibular (balance) division of this nerve, which is why the more accurate medical term is vestibular schwannoma.

The tumour sits inside or near the internal auditory canal (a narrow bony tunnel running from the inner ear toward the brainstem) and the cerebellopontine angle (the space between the cerebellum and the brainstem). Several critical structures pass through or near this space, including the facial nerve, which controls facial movement, and the trigeminal nerve, which carries sensation from the face.

The surgery is performed by a team that usually includes a neurosurgeon and a neurotologist (an ear surgeon with specialist training in skull base surgery). The goal is to remove as much tumour as can safely be taken out while protecting the facial nerve, and where possible, preserving hearing. Modern surgery is performed under a microscope or endoscope, with continuous monitoring of the facial nerve and sometimes the cochlear (hearing) nerve during the operation.

Why Is Acoustic Neuroma Surgery Performed?

Not every acoustic neuroma needs to be removed. Many small, slow-growing tumours are simply watched with regular MRI scans. Surgery is considered when one or more of the following situations applies:

• The tumour is growing. Serial MRI scans show measurable enlargement over time.
• The tumour is already large at diagnosis. Larger tumours press on the brainstem and cerebellum and are usually treated rather than observed.
• Symptoms are progressing. Worsening hearing loss, dizziness, imbalance, facial numbness, or headaches may push the decision toward intervention.
• Hydrocephalus. A very large tumour can block the normal flow of cerebrospinal fluid and cause a build-up of pressure inside the skull.
• The patient prefers definitive removal. Some patients prefer to deal with the tumour while they are younger and healthier rather than monitor it for many years.
• The tumour is unsuitable for radiosurgery. Very large tumours, or those causing significant brainstem compression, are generally beyond the safe range for stereotactic radiosurgery.

Decisions about timing depend on tumour size on MRI, your hearing in the affected ear and the other ear, the presence of balance or facial symptoms, your age, and your overall health.

Who Is a Candidate?

A patient may be a candidate for acoustic neuroma surgery when:

• The tumour is medium to large, or has grown on follow-up scans
• The tumour is compressing the brainstem or cerebellum
• Stereotactic radiosurgery is not suitable, has been declined, or has failed to control the tumour
• The patient is fit enough to undergo several hours of general anaesthesia and a craniotomy or skull base procedure
• The patient has a reasonable life expectancy and prefers a one-time definitive treatment

Patients with very small tumours and stable hearing, very elderly patients with slow-growing tumours, or those with significant other medical conditions may be guided toward observation or radiosurgery instead. Patients with neurofibromatosis type 2 (NF2) — a genetic condition that causes tumours on both vestibular nerves — are managed by specialised teams who balance hearing preservation across both sides and may use combinations of surgery, radiosurgery, and medical therapy.

Alternatives to Surgery

Surgery is one of three accepted management options for acoustic neuroma. The other two — observation and stereotactic radiosurgery — are appropriate in many situations, and the choice between them is one of the most important conversations to have with the treating team.

Observation (Watch and Wait)

Because most acoustic neuromas grow slowly, and some do not grow at all, observation with periodic MRI is a legitimate strategy for small tumours with mild or stable symptoms. Scans are typically repeated at six-month or yearly intervals at first, and the interval is lengthened if the tumour remains stable. Hearing tests are usually done alongside the scans. Treatment is considered if the tumour grows, if symptoms worsen, or if hearing declines.

The advantage of observation is that it avoids the risks of surgery and radiation in patients whose tumours may never need treatment. The disadvantage is the psychological weight of living with a known tumour, and the possibility that hearing may be lost during the observation period regardless of whether the tumour grows.

Stereotactic Radiosurgery

Stereotactic radiosurgery delivers a precisely focused dose of radiation to the tumour in a single session or a small number of sessions, using systems such as Gamma Knife, CyberKnife, or linear accelerator-based platforms. It is not surgery in the conventional sense — there is no incision and no general anaesthesia. The aim is to stop the tumour from growing rather than to remove it.

Radiosurgery is most often used for small to medium-sized tumours (generally up to around 2.5 to 3 cm in the cerebellopontine angle, though limits vary by centre). Tumour growth control rates over many years are high in published series. Hearing preservation in the short term is reasonable, but hearing in the affected ear tends to decline over the years that follow. Facial nerve risk is generally low but not zero.

Radiosurgery is not appropriate for very large tumours, tumours causing brainstem compression or hydrocephalus, or in some cases where definitive removal is preferred. If a tumour continues to grow after radiosurgery, later surgery is still possible but can be technically more difficult because of scarring.

Choosing Between the Options

The choice among observation, radiosurgery, and surgery depends on tumour size, growth pattern, hearing, age, the presence of brainstem compression, and personal preference. Major neurosurgical and neurotological societies describe all three as accepted options in appropriate situations, and skull base teams typically discuss the choice with the patient over more than one visit.

Surgical Approaches

Retrosigmoid (Suboccipital) Approach

The retrosigmoid approach reaches the tumour from behind the ear, through an opening in the back of the skull behind the sigmoid sinus (a large vein). The cerebellum is gently retracted to expose the cerebellopontine angle and the tumour.

This approach can be used for tumours of nearly any size and offers the possibility of preserving hearing when useful hearing is still present before surgery. It gives a wide view of the brainstem and the surrounding nerves. The trade-off is that the lateral end of the internal auditory canal can be difficult to see fully, so additional bone removal may be needed to reach tumour at the far end of the canal. Post-operative headache is a recognised complication of this route in some patients.

Translabyrinthine Approach

The translabyrinthine approach goes through the bone behind the ear and through the inner ear’s balance organs (the labyrinth). Because the route passes through the labyrinth, all hearing in that ear is lost as part of the operation. This approach is therefore chosen when hearing in the affected ear is already poor and not worth preserving, or when the tumour is too large for hearing preservation to be realistic.

The main advantage is excellent exposure of the facial nerve along its course in the internal auditory canal, which can help with facial nerve preservation. Because the cerebellum does not need to be retracted, some of the complications related to cerebellar manipulation are reduced. Vestibular (balance) function on that side is also removed by this approach, which sometimes makes balance adjustment after surgery more predictable.

Middle Cranial Fossa Approach

The middle fossa approach reaches the tumour from above the ear, through the floor of the middle cranial fossa. This route is generally used for small tumours that are confined to the internal auditory canal, particularly when the goal is to preserve serviceable hearing. It gives excellent access to the lateral end of the internal auditory canal, where retrosigmoid exposure can be limited.

The middle fossa approach involves some temporal lobe retraction, and it is technically demanding. It is most often offered at centres with significant skull base experience and is reserved for selected smaller tumours.

How the Approach Is Chosen

In practice, the team considers tumour size, position, hearing level, and patient factors together. As a general pattern:

• Small intracanalicular tumours with useful hearing — middle fossa or retrosigmoid
• Small to medium tumours with poor hearing — translabyrinthine
• Medium to large tumours with useful hearing — retrosigmoid with hearing preservation attempt
• Large tumours with brainstem compression — retrosigmoid or translabyrinthine, depending on hearing and team preference

The exact approach should be discussed with the surgical team, who will explain their reasoning in your specific case.

Preparing for Surgery

Preparation for acoustic neuroma surgery usually begins several weeks before the operation and involves a combination of imaging, hearing tests, anaesthesia review, and counselling.

Investigations

• MRI of the brain and internal auditory canals with contrast is the key imaging test. It defines tumour size, position, and relationship to the brainstem, cerebellum, and surrounding nerves.
• Audiometry (a formal hearing test) measures hearing in both ears. Word recognition scores are particularly important when hearing preservation is being considered.
• Vestibular testing may be done in some centres to assess balance function on each side.
• CT scan may be used in addition to MRI to evaluate the bony anatomy.
• Routine pre-anaesthetic workup — blood tests, ECG, chest X-ray, and other investigations depending on age and health.

Medical Optimisation

Conditions such as high blood pressure, diabetes, or heart disease should be well controlled before surgery. Blood-thinning medications, including aspirin and anticoagulants, are usually paused before the operation according to the surgical team’s instructions. Smoking cessation, even for a short period before surgery, can improve healing and reduce respiratory complications.

Counselling on Expected Outcomes

Realistic counselling is an important part of preparation. Before surgery, the team usually discusses:

• The likelihood of complete versus near-complete tumour removal in your case
• The expected outcome for hearing in the operated ear
• The risk of temporary or permanent facial weakness
• What balance and headache symptoms to expect afterwards
• The plan for follow-up MRI scans

It is reasonable to ask the team how many of these procedures they perform each year and what their typical outcomes are for tumours of your size.

What Happens During Surgery

Acoustic neuroma surgery is performed under general anaesthesia and typically takes between four and ten hours, depending on tumour size, the approach used, and the difficulty of separating the tumour from the facial and cochlear nerves.

The general sequence of events is:

1. Anaesthesia and positioning. You are placed under general anaesthesia and positioned on the operating table according to the approach — usually on your back with the head turned, or in a semi-sitting position in some centres.
2. Nerve monitoring. Fine electrodes are placed on the face and sometimes near the cochlea so the team can monitor the facial nerve (and where relevant the hearing nerve) throughout the operation. This continuous feedback helps the surgeon identify and protect these nerves while removing tumour.
3. Skin incision and bone removal. An incision is made depending on the approach. Bone is removed to create a window through the skull and reach the tumour. The bony work is precise and may take a significant portion of the operating time.
4. Tumour removal. Working under the operating microscope, the surgical team enters the cerebellopontine angle, identifies the tumour and the nerves, and removes the tumour piece by piece. The facial nerve is identified early and protected. In some cases, a small amount of tumour is intentionally left behind on the facial nerve to reduce the risk of facial weakness; any residual tumour is then watched or treated with radiosurgery later if it grows.
5. Closure. The bony defect is reconstructed using bone, fat, muscle, or synthetic material to prevent leakage of cerebrospinal fluid. The wound is closed in layers.

The Hospital Stay

Most patients spend one night in intensive care or a step-down unit, then move to a regular ward. Total hospital stay is typically four to seven days, though it can be longer if there are complications such as a cerebrospinal fluid leak, prolonged dizziness, or wound issues.

In the first days you may experience:

• Dizziness and unsteadiness when sitting up or walking
• Nausea, often related to the balance change and to the anaesthetic
• Headache, sometimes severe in the first few days
• Some facial weakness, which may improve over weeks or months
• Dry eye on the affected side, particularly if the facial nerve is weak
• A change or loss of hearing in the operated ear
• Tinnitus (ringing) in the operated ear

Physiotherapy usually starts during the hospital stay, focusing on safe walking and balance retraining. The team will also teach you how to look after the eye on the affected side if facial weakness is present.

The First Few Weeks at Home

Most patients are tired for several weeks. Headache, imbalance, and ear symptoms typically improve gradually but unevenly. Activities are usually restricted in the early weeks:

• Avoid heavy lifting, straining, and vigorous exercise until cleared by the surgical team
• Avoid air travel until cleared, usually a few weeks
• Avoid swimming and submerging the head until the wound is fully healed
• Walk regularly to help balance recover

Driving is usually restricted until balance and any visual changes have settled and the surgical team has cleared you.

Longer-Term Recovery

The brain adapts to the loss of vestibular input from the operated side through a process called vestibular compensation. This takes weeks to months and is helped greatly by staying active and by vestibular rehabilitation exercises, particularly for those who have persistent imbalance. Many patients feel substantially better by three to six months, with continued, slower improvement up to a year or more.

Facial nerve function, when affected, may continue to recover for six to twelve months or sometimes longer. Hearing in the operated ear, if lost, does not return.

Risks and Complications

Acoustic neuroma surgery is a major operation in a delicate area of the skull base. Modern outcomes at experienced centres are good, but a number of specific risks need to be understood.

Facial Nerve Injury

The facial nerve runs alongside or is sometimes stretched and flattened by the tumour. Some degree of facial weakness after surgery is common, particularly with larger tumours. In many cases it is temporary and improves over weeks to months. Permanent partial or complete facial weakness can occur, especially with very large tumours. Severity is described using grading systems such as the House-Brackmann scale.

Persistent facial weakness can affect eye closure, smiling, eating, and speech. Treatments include eye care (artificial tears, ointment, sometimes a small weight placed in the upper eyelid to help it close), physiotherapy and facial rehabilitation, botulinum toxin injections for synkinesis (unwanted associated movements), and in selected cases, reconstructive surgery on the face or nerve.

Hearing Loss

Hearing is often already reduced on the affected side before surgery. Depending on the approach and tumour size, hearing in the operated ear is sometimes preserved, but in many cases it is lost. The translabyrinthine approach always results in complete hearing loss on that side. Even when preservation is attempted, success depends on tumour size and pre-operative hearing.

Single-sided deafness affects sound localisation and hearing in background noise. Devices such as bone-anchored hearing systems or CROS hearing aids can help in some situations.

Cerebrospinal Fluid Leak

A leak of cerebrospinal fluid (CSF) through the wound or, less obviously, through the nose or ear is a recognised complication. Small leaks may settle with bed rest. Larger leaks may need lumbar drainage or a further procedure to seal the defect. Untreated CSF leaks carry a risk of meningitis.

Balance Problems

Because the tumour grows on a balance nerve, that nerve is sacrificed during surgery if it has not already been damaged by the tumour. Most patients experience some imbalance afterwards. The brain usually compensates over weeks to months, particularly with vestibular rehabilitation. A small number of patients have persistent imbalance, especially in low-light conditions or on uneven ground.

Other Risks

• Headache — can be persistent in some patients, particularly after the retrosigmoid approach
• Tinnitus — may worsen, improve, or remain unchanged
• Other cranial nerve injuries — trigeminal nerve (facial sensation), lower cranial nerves (swallowing, voice) are at risk with very large tumours
• Bleeding or stroke — uncommon but serious
• Infection — including meningitis
• Hydrocephalus — may develop after surgery in some cases and require a shunt
• Anaesthetic and general surgical risks — including blood clots, chest infections
• Tumour recurrence or regrowth — uncommon after complete removal, but possible, especially when some tumour was left behind to protect the facial nerve. Regrowth is followed on MRI and may be treated with radiosurgery or further surgery.

Life After Surgery

Most patients return to normal daily activities over weeks to months, though the timeline varies. Office work is often resumed within four to eight weeks for uncomplicated recoveries; physically demanding work or work that requires good balance and hearing may take longer.

Adjusting to Hearing and Balance Changes

If hearing in the operated ear is lost, the brain gradually adapts to single-sided hearing. Strategies that help include positioning conversations on the hearing side, reducing background noise where possible, and considering hearing devices designed for single-sided deafness. Audiology review is often helpful.

Eye and Facial Care

If the facial nerve is weak, protecting the eye is the immediate priority. Artificial tears during the day, ointment at night, and sometimes taping the eye shut at night or wearing a moisture chamber prevent the cornea from drying out and being damaged. An eye specialist may be involved if the weakness is significant or prolonged. As the facial nerve recovers, specific facial retraining exercises with a therapist experienced in facial rehabilitation can improve the quality of recovery and reduce synkinesis.

Emotional Adjustment

Living through brain surgery for a tumour, even a benign one, can be emotionally difficult. Some patients experience anxiety, low mood, or post-traumatic feelings in the months afterwards, sometimes related to body image changes from facial weakness or to ongoing symptoms. Talking to a counsellor, joining a patient support group, or speaking openly with your medical team can all help.

Follow-Up Imaging

Follow-up MRI scans are part of long-term care. The schedule varies by centre and by how much tumour was removed, but typically a baseline scan is done a few months after surgery, with further scans at intervals over several years. If any residual tumour was intentionally left behind, scans monitor it closely for growth.

Acoustic Neuroma and Genetic Considerations

Most acoustic neuromas are sporadic and occur on one side. A small proportion are linked to neurofibromatosis type 2 (NF2), a genetic condition in which tumours typically develop on both vestibular nerves. NF2 is usually diagnosed at a younger age than sporadic acoustic neuroma and is managed by specialised teams. The treatment principles are similar, but the priority of preserving hearing and facial function across both sides changes how decisions about timing and approach are made. Patients with bilateral tumours, very early-onset tumours, or a family history should be evaluated for NF2 by a clinical geneticist or a specialised skull base team.

Frequently Asked Questions

Is acoustic neuroma cancer?

No. Acoustic neuroma (vestibular schwannoma) is a benign tumour. It does not spread to other parts of the body. However, because it grows in a confined space near important structures, it can cause significant symptoms if it enlarges, which is why treatment is sometimes recommended.

Will I lose my hearing?

It depends on tumour size, the surgical approach, and the hearing level before surgery. Translabyrinthine surgery always results in loss of hearing in that ear. Retrosigmoid and middle fossa approaches can preserve hearing in selected cases, particularly for smaller tumours with good pre-operative hearing, but preservation is not guaranteed. Your team will give you a more specific estimate based on your tumour and audiogram.

Will my face be paralysed?

Some degree of facial weakness after surgery is common, especially with larger tumours, but in many cases it is temporary. Modern facial nerve monitoring during surgery has substantially improved outcomes. Permanent significant facial weakness is a real but less common outcome, and depends heavily on tumour size and how closely the tumour was attached to the facial nerve.

Why might my surgeon leave some tumour behind?

When a portion of tumour is very tightly stuck to the facial nerve, removing every last piece can risk permanent facial weakness. In that situation, leaving a small amount of tumour can preserve facial function. The remaining piece is then monitored with MRI and treated with radiosurgery or further surgery only if it grows. This is a deliberate trade-off increasingly used at experienced centres.

How long will I be in hospital?

Most patients stay in hospital for about four to seven days, beginning with one night in intensive care or a high-dependency unit. The stay can be longer if there are complications such as a CSF leak or significant dizziness.

When can I go back to work?

For office-based work, return is often possible at around four to eight weeks for uncomplicated recoveries. Work that requires physical strength, balance, or full hearing on both sides may take longer. The surgical team will guide this based on how recovery is going.

Can the tumour come back?

After complete removal, recurrence is uncommon. When some tumour has been left behind to protect the facial nerve, regrowth can occur over years and is followed on MRI. If regrowth is seen, options include further surgery or radiosurgery.

How is surgery different from Gamma Knife or radiosurgery?

Surgery physically removes the tumour. Radiosurgery delivers focused radiation to stop the tumour from growing without removing it. Surgery is generally preferred for larger tumours and for tumours causing brainstem compression. Radiosurgery is generally preferred for smaller tumours, particularly in older patients or those who prefer to avoid an operation. Both have evidence supporting their use in appropriate situations, and the choice is made together with the treating team.

Will I still have dizziness after surgery?

Some imbalance is normal in the early weeks after surgery because the balance nerve on the operated side no longer works. The brain compensates over weeks to months, helped by staying active and by vestibular rehabilitation. Most patients improve substantially, though some have persistent symptoms, especially in challenging visual conditions such as walking on uneven ground at night.

Do I need to follow up forever?

Long-term follow-up with periodic MRI scans is standard. The intervals between scans usually lengthen if everything remains stable. Hearing and facial function may also be reviewed regularly in the first year or two.

Conclusion

Acoustic neuroma surgery is a well-established treatment for a benign but anatomically demanding tumour. The decision to operate, the choice of surgical approach, and the goals of surgery — complete removal versus a planned subtotal resection to protect facial function — are individualised. Observation and stereotactic radiosurgery remain important alternatives that are appropriate for many patients, and the conversation between patient and skull base team usually takes place over more than one visit.

Outcomes have improved significantly over the past decades with better imaging, intraoperative nerve monitoring, refined surgical techniques, and a culture of multidisciplinary care between neurosurgeons and neurotologists. Recovery takes time, and adapting to changes in hearing, balance, or facial function is part of the longer journey. Working closely with the surgical team, the rehabilitation team, and, where helpful, a counsellor or patient support group can make that journey easier.