Acoustic Neuroma

Introduction

If you have recently been told you have an acoustic neuroma, you are probably absorbing a lot of new information at once. The diagnosis often comes after months or years of subtle symptoms — hearing that is not quite right in one ear, a persistent ringing, or a sense of being off-balance — and is usually confirmed by an MRI scan. The good news is that acoustic neuromas are almost always benign, meaning they are not cancer, and they typically grow very slowly. The harder part is deciding what to do next.

This article is written for people who have an acoustic neuroma diagnosis or who are being investigated for one, and for their families. It explains what the tumour is, how it is monitored and treated, what each treatment option involves, and what life tends to look like during and after care. The decision about which path to take is highly individual and is made together with an ENT (ear, nose and throat) specialist, a neurosurgeon, and sometimes a radiation oncologist. Our aim here is to give you the background you need for that conversation.

What Is an Acoustic Neuroma?

An acoustic neuroma is a benign (non-cancerous) tumour that grows on the vestibulocochlear nerve — the eighth cranial nerve, which carries signals about hearing and balance from the inner ear to the brain. The more accurate medical name is vestibular schwannoma, because the tumour develops from Schwann cells, which form the protective sheath around the nerve fibres. Although “acoustic neuroma” is the term most patients know and the one used throughout this article, you may also see “vestibular schwannoma” in your medical reports.

The tumour begins inside a bony canal in the skull called the internal auditory canal, where the nerve runs from the inner ear toward the brainstem. As it enlarges, it can press on the nearby facial nerve (which controls movement of the face), the trigeminal nerve (which carries facial sensation), and eventually the brainstem and cerebellum if it grows large enough.

Key points about acoustic neuromas:

• They are benign — they do not spread to other parts of the body.
• They are slow growing in most people. Many grow by only 1–2 millimetres per year, and some do not grow at all over years of monitoring.
• They usually affect one ear only. Tumours on both sides are uncommon and are linked to a genetic condition called neurofibromatosis type 2 (NF2).
• They are most often diagnosed in adults between 40 and 60, though they can occur at any age.

Because the tumour grows in a confined space near important nerves, even a small, non-cancerous lesion can cause meaningful symptoms. The management challenge is balancing the risks of the tumour itself against the risks of treating it.

Causes and Risk Factors

For most people with an acoustic neuroma, no specific cause is identified. The tumour arises from a change in the genetic instructions within a Schwann cell that allows it to multiply when it should not. Why this happens in one person and not another is generally unknown.

Known and suspected factors include:

• Neurofibromatosis type 2 (NF2): A rare inherited condition in which acoustic neuromas develop on both sides, often at a younger age, and alongside other nervous system tumours. Only a small minority of acoustic neuromas are due to NF2.
• Previous radiation to the head and neck: A history of radiation in childhood is a recognised risk factor for nerve sheath tumours later in life.
• Age: Most sporadic (non-NF2) cases appear in middle adulthood.

Other factors that have been studied — including mobile phone use and occupational noise exposure — have not been shown in current evidence to cause acoustic neuromas. If you have one, it is almost certainly not because of something you did or did not do.

Signs and Symptoms

Most people are diagnosed with an acoustic neuroma after weeks or months of slowly progressing symptoms that affect one ear. If you are reading this with a diagnosis already in hand, you may recognise several of the following. This section is included so you can understand what is happening physiologically and so you can recognise new or worsening symptoms during follow-up.

Hearing changes

The most common symptom is gradual hearing loss in one ear. The loss is often subtle at first — difficulty understanding speech on the phone, trouble hearing in a noisy restaurant, or noticing that one ear works less well than the other. Less commonly, hearing loss appears suddenly.

Tinnitus

A persistent ringing, buzzing, or hissing sound in the affected ear is reported by most patients. The pitch and pattern vary, and tinnitus can be present even when hearing loss is mild.

Balance and dizziness

Because the tumour grows on a nerve that carries balance information, many people experience a sense of unsteadiness, especially in the dark or on uneven ground. True spinning vertigo is less common but does occur. The brain often compensates over time, so balance symptoms can be mild even with a moderately sized tumour.

Symptoms from pressure on nearby structures

As a tumour enlarges, it may press on adjacent nerves and tissues, causing:

• Numbness, tingling, or pain in part of the face (trigeminal nerve)
• Facial weakness or twitching (facial nerve, though this is uncommon before treatment)
• Headaches
• In larger tumours: difficulty swallowing, double vision, or signs of pressure inside the skull

If you develop new facial weakness, severe headache with vomiting, sudden vision changes, or a marked drop in alertness, this is a reason to seek urgent medical assessment regardless of where you are in your care pathway.

Diagnosis

An acoustic neuroma diagnosis is usually built from three elements: a careful history and examination, hearing tests, and imaging.

History and examination

The ENT specialist will ask in detail about hearing, tinnitus, balance, facial sensation, and any neurological symptoms, and will examine the ears, cranial nerves, and balance function. Asymmetric hearing loss — hearing that is worse in one ear than the other — is often what prompts further investigation.

Audiometry (hearing test)

A pure-tone audiogram measures how well each ear hears across a range of frequencies. A speech discrimination score — how clearly you can understand spoken words — is also recorded. In acoustic neuroma, the speech discrimination score is often disproportionately poor compared to the pure-tone loss, particularly for high frequencies.

MRI of the brain and internal auditory canal

Tumour size is usually reported in millimetres, measured at the largest dimension of the part of the tumour that extends beyond the bony canal into the space behind the ear (the cerebellopontine angle). General size categories used in planning are:

• Intracanalicular: Entirely inside the internal auditory canal.
• Small: Up to about 1.5 cm of extension beyond the canal.
• Medium: About 1.5–3 cm.
• Large: More than 3 cm, often with pressure on the brainstem.

Other tests

Additional tests may include balance testing (videonystagmography or VNG), an auditory brainstem response (ABR) test, and a CT scan if more detail of the bony anatomy is needed. If NF2 is suspected, genetic testing and screening for other tumours may be discussed.

Treatment and Management

There are three established management pathways for acoustic neuroma: observation, stereotactic radiosurgery, and microsurgical removal. None is universally better than the others. The right choice depends on tumour size and growth rate, your age and general health, the hearing in the affected ear and the other ear, your symptoms, and your preferences about risk.

Major specialty bodies, including the American Academy of Otolaryngology-Head and Neck Surgery and the Congress of Neurological Surgeons, describe all three as legitimate options in appropriate situations. The decision is best made in a consultation that involves both an ENT/neuro-otology specialist and a neurosurgeon, often together.

Observation (watch and scan)

Many acoustic neuromas grow slowly or not at all, particularly small ones found incidentally. For these tumours, the option to monitor with regular MRI scans is well established. A typical pattern is an MRI 6–12 months after diagnosis, then every year for several years, with intervals lengthening if the tumour is stable.

Observation is often considered when:

• The tumour is small and not pressing on the brainstem.
• Symptoms are mild or stable.
• The patient is older, or has medical conditions that make active treatment riskier.
• Hearing on the affected side is already poor (so there is less to lose by waiting) or, conversely, hearing is good and the patient wants to avoid the hearing risk of intervention.

The trade-off is that if the tumour does grow, the choice between radiosurgery and microsurgery becomes more constrained, and hearing in the affected ear often declines over time even without intervention.

Stereotactic radiosurgery

Stereotactic radiosurgery is a non-surgical treatment that uses precisely focused beams of radiation to stop the tumour from growing. Despite the word “surgery,” there is no incision. The most common platforms are Gamma Knife and CyberKnife; linear accelerator (LINAC) systems are also used. Treatment is usually delivered in a single session, though some centres use a small number of sessions (fractionated stereotactic radiotherapy) for selected tumours.

The goal of radiosurgery is tumour control — preventing further growth — rather than removal. In the years after treatment, the tumour may shrink, stay the same size, or temporarily swell before stabilising. Control rates reported in the clinical literature are high, particularly for tumours under about 3 cm.

Radiosurgery is often considered for:

• Small to medium tumours.
• Patients for whom open surgery carries higher risk.
• Tumours that have grown during a period of observation.
• Residual or recurrent tumour after previous surgery.

The main risks include gradual hearing loss in the treated ear, balance disturbance, facial numbness, and, less commonly, facial nerve weakness. Very rarely, the tumour itself transforms into a more aggressive lesion after radiation; this risk is small but is a reason radiosurgery is used more cautiously in younger patients with very long life expectancy.

Microsurgical removal

Microsurgery means physically removing the tumour through an opening in the skull, using an operating microscope and continuous monitoring of the facial nerve and other structures. It is the option most likely to remove the tumour completely and is often favoured for larger tumours, especially those pressing on the brainstem, and for patients with significant balance symptoms or rapid growth.

Translabyrinthine approach. The surgeon reaches the tumour through the mastoid bone behind the ear, passing through the balance organ (labyrinth). This gives an excellent view of the facial nerve, but the inner ear is removed in the process, so any remaining hearing in that ear is sacrificed. It is often chosen when hearing is already poor or when preserving hearing is not the priority.

Retrosigmoid (suboccipital) approach. The surgeon enters through an opening in the skull behind the ear. This approach can be used for tumours of any size and offers a chance to preserve hearing if hearing is still good before surgery. It also gives good access to the brainstem for larger tumours.

Middle fossa approach. The surgeon enters through an opening above the ear. This is used mainly for small tumours that are confined to the internal auditory canal, when there is a real chance of preserving hearing.

In some cases, particularly with large tumours close to vital structures, surgeons may deliberately leave a small piece of tumour behind to protect the facial nerve and other functions. The residual portion can then be monitored or treated with radiosurgery if it grows.

How the choice is made

In current practice, the conversation about which path to take typically considers:

• Tumour size and growth. Small, stable tumours often suit observation; growing tumours prompt active treatment; large tumours usually require surgery.
• Hearing. If useful hearing remains on the affected side and the patient wants to try to preserve it, the choice between hearing-preserving radiosurgery and a hearing-preserving surgical approach is weighed carefully.
• Age and overall health. Older patients or those with other conditions may be steered away from longer general anaesthesia.
• Symptoms. Severe balance symptoms or facial nerve involvement may tilt the decision toward surgery.
• Patient preference. Some people are more comfortable with a one-time procedure that removes the tumour; others prefer a non-invasive option that controls growth.

Whether any particular option is appropriate for you is a clinical decision made with your team after reviewing your MRI, audiogram, and overall picture.

Preparing for Treatment

If you and your team decide on active treatment, preparation depends on which option you choose.

For radiosurgery, preparation usually involves a planning MRI and CT scan, fitting of a head frame or mask to keep the head still during treatment, and a session with the radiation team to map the dose. Treatment itself is typically a single day, and most people go home the same day.

For microsurgery, preparation includes:

• Pre-anaesthetic assessment, blood tests, and ECG.
• Detailed discussion of the surgical approach and the specific risks for your tumour.
• Instructions about medications to stop or continue, fasting, and skin preparation.
• Sometimes a baseline assessment by a physiotherapist for balance, and audiology testing.
• Planning for hospital stay, which is commonly several days, and for support at home afterwards.

It is reasonable to ask the surgical team how often they perform acoustic neuroma surgery, what their typical approach is for tumours like yours, and how they monitor the facial nerve during the operation. Outcomes for acoustic neuroma surgery are strongly linked to experience, so a team that handles a high volume of these cases is generally preferred by major guidelines.

Recovery and What to Expect After Treatment

After radiosurgery

Recovery from radiosurgery is generally quick. Most people resume normal activities within a few days. Mild headache, nausea, or fatigue in the first few days is not unusual. Hearing, balance, and facial sensation may change gradually over months and years, so follow-up MRI and audiograms are scheduled periodically — often at 6 and 12 months, then yearly for several years, then less often if the tumour is stable.

It is important to understand that radiosurgery does not make the tumour disappear quickly. The MRI may show the tumour unchanged or even slightly larger for a year or two before it stabilises or shrinks. This is expected and is not the same as treatment failure.

After microsurgery

Hospital stay after acoustic neuroma surgery is typically several days, with the first 24–48 hours in a high-dependency or neurosurgical care unit. Common experiences during recovery include:

• Headache for days to weeks, sometimes longer.
• Fatigue, often more pronounced than people expect, lasting weeks to months.
• Imbalance and dizziness as the brain adapts to changes in balance signals from the operated side. This usually improves with time and vestibular rehabilitation.
• Hearing loss on the operated side, complete with some approaches and possible with others.
• Facial nerve changes — weakness, slowed blink, or altered taste — that may be temporary or longer-lasting.
• Numbness around the incision and sometimes in part of the face.

Vestibular rehabilitation

Specialised physiotherapy — vestibular rehabilitation — helps the brain adapt to changes in balance after both surgery and radiosurgery. Exercises typically include eye-head coordination drills, balance retraining, and graded walking. Starting these exercises soon after treatment, under guidance, generally helps balance recover faster.

Facial nerve care

If the facial nerve is weak after treatment, eye protection is a priority. A weak blink can leave the eye dry and prone to injury. Measures may include lubricating eye drops, an eye ointment at night, taping the eye closed during sleep, and in some cases a small weight placed on the upper eyelid by an ophthalmologist or facial nerve specialist. Most temporary facial weakness improves significantly over 6–12 months, and facial rehabilitation with a specialised therapist can help recovery and reduce unwanted muscle co-movements (synkinesis).

Risks and Complications

Every option carries some risk, including observation, in which the main risk is that the tumour grows and limits future options.

For radiosurgery, recognised risks include:

• Gradual hearing loss in the treated ear.
• Tinnitus, balance changes, or facial numbness.
• Facial weakness, less common with modern dosing.
• Temporary or persistent tumour swelling, occasionally requiring further treatment.
• Rarely, hydrocephalus (build-up of fluid in the brain) or, very rarely, malignant transformation.

For microsurgery, risks include:

• Facial nerve weakness, ranging from mild and temporary to permanent.
• Hearing loss on the operated side (complete with translabyrinthine, variable with others).
• Persistent balance difficulty.
• Cerebrospinal fluid (CSF) leak from the wound or through the nose, sometimes needing a small procedure to correct.
• Headache, including chronic post-operative headache in a minority of patients.
• Meningitis (infection of the lining of the brain), which is uncommon but serious.
• Stroke, bleeding, or other major neurological complications — uncommon but possible with surgery near the brainstem.
• Need for further treatment if any tumour remnant grows.

Your team will go through the risks that apply to your specific tumour and treatment plan in detail. Asking what the most likely outcomes are — not just the worst-case scenarios — can be a helpful way to frame the discussion.

Hearing, Balance, and Facial Function: Living with the Long-Term Effects

If hearing is lost on the affected side, the main challenges are understanding speech in noisy environments and judging where sounds are coming from. Options to consider include:

• CROS hearing aids (Contralateral Routing of Signal), which pick up sound on the deaf side and route it to the better-hearing ear.
• Bone conduction devices, which transmit sound through the skull to the inner ear of the better-hearing side.
• Cochlear implants in selected cases, particularly in NF2 or when the hearing nerve has been preserved.
• Practical strategies such as positioning yourself with the better ear toward the speaker, reducing background noise, and using subtitles.

An audiologist with experience in single-sided deafness can help compare these options.

Balance

The brain typically learns to rely more on the unaffected balance organ and on vision and proprioception (sense of body position). Most people compensate well, especially with vestibular rehabilitation. Some find that fatigue, illness, or dark environments bring back a sense of unsteadiness; this is common and not a sign that something is wrong.

Facial function

If facial weakness persists, options include facial physiotherapy, botulinum toxin to balance the two sides of the face, eyelid procedures to protect the eye, and reconstructive surgery in select cases. Specialised facial nerve clinics can be a valuable resource.

Tinnitus and emotional wellbeing

Tinnitus often remains after treatment, even when the tumour is controlled. Sound therapy, cognitive behavioural therapy approaches, and hearing aids can reduce its impact. Many people also find an adjustment period emotionally challenging — learning that you have a brain tumour, even a benign one, and going through treatment is a significant life event. Support from family, patient groups, and where needed a counsellor or psychologist is a normal part of recovery for some patients.

Monitoring and Follow-up

Whatever pathway is chosen, long-term follow-up is part of acoustic neuroma care.

• Observation: MRI scans at intervals, typically more frequent in the first 1–2 years and then less frequent if the tumour is stable. Audiograms may be repeated to track hearing.
• After radiosurgery: MRI and audiogram follow-up over many years, because the goal is long-term control rather than removal.
• After microsurgery: MRI follow-up to check for any residual or recurrent tumour. The schedule depends on whether the tumour was completely removed and on the surgical team's protocol.

It is worth keeping copies of your scans and reports. If you move to a different city or country for ongoing care, having the original imaging available greatly helps any new team.

Acoustic Neuroma in the Context of NF2

A small number of acoustic neuromas occur as part of neurofibromatosis type 2, a genetic condition in which both hearing nerves develop tumours, and other nervous system tumours may also be present. NF2 management is more complex and is usually coordinated through specialised centres. It involves attention to both ears, careful timing of any treatment to preserve hearing for as long as possible, and consideration of treatments such as cochlear or auditory brainstem implants, and targeted medical therapies in some cases. If NF2 is suspected, genetic counselling and screening of close family members are typically discussed.

Acoustic neuromas in children are rare and, when they occur, are most often in the context of NF2. Children with NF2 are usually cared for in paediatric neuro-oncology or specialised NF2 services rather than general adult acoustic neuroma clinics.

When to Seek Urgent Care

Most acoustic neuroma symptoms develop gradually and do not require emergency care. However, contact your care team or seek urgent medical assessment if you experience:

• Sudden, severe headache, especially with vomiting or neck stiffness.
• Sudden vision changes, double vision, or loss of consciousness.
• New, rapidly worsening facial weakness.
• Sudden, severe vertigo with inability to stand.
• After surgery: fever, clear fluid leaking from the nose or wound, increasing redness or swelling at the surgical site, or signs of meningitis (severe headache, neck stiffness, fever, confusion).

Frequently Asked Questions

Is an acoustic neuroma cancer?

No. Acoustic neuromas are benign tumours. They do not spread to other parts of the body. The concern is local — the tumour can press on nearby nerves and, if large, on the brainstem.

Will my acoustic neuroma definitely grow?

Not necessarily. Many small tumours grow very slowly or not at all over years of monitoring. This is one of the reasons observation is a legitimate first step for many people. Growth, if it happens, is the trigger for active treatment.

Will I lose my hearing?

Hearing in the affected ear often declines over time, with or without treatment. Whether useful hearing can be preserved depends on the size of the tumour, current hearing level, the option chosen, and individual anatomy. Your audiogram and MRI will guide the conversation. Hearing in the other ear is not affected by a one-sided acoustic neuroma.

Is surgery or radiosurgery “better”?

Neither is universally better. For small to medium tumours, both options have high control rates, and the choice often comes down to individual factors and patient preference. For large tumours, surgery is usually needed. Specialists who offer both options, or multidisciplinary teams that include them, are well placed to give a balanced view.

How long does recovery take after surgery?

Most people are home within about a week and back to light activities in 4–6 weeks. Returning to full work, exercise, and energy levels often takes 2–6 months, and balance can continue to improve over the first year. Recovery is faster and smoother for smaller tumours.

Can the tumour come back after treatment?

After complete surgical removal, recurrence is uncommon but possible, which is why follow-up MRI is part of long-term care. After radiosurgery, the tumour is not removed but controlled; long-term scans check that it remains stable. After observation, “coming back” is not the right framing — the question is whether the existing tumour grows.

Can I fly, exercise, or travel after treatment?

Most people return to flying and normal exercise after the early recovery period, with timing guided by the treating team. Diving and activities involving rapid pressure changes are sometimes restricted after certain surgical approaches; ask your surgeon specifically.

Should I get a second opinion?

Acoustic neuroma decisions are significant and often not urgent. Many patients find it helpful to discuss their case with more than one specialist or with a multidisciplinary team that includes both an ENT/neuro-otology surgeon and a neurosurgeon experienced in this condition. Major guidelines support patient involvement in choosing among options, which is easier with a clear understanding of the trade-offs.

Conclusion

An acoustic neuroma diagnosis is unsettling, but it is rarely an emergency, and the field has developed three well-established management pathways — observation, radiosurgery, and microsurgery — that can be tailored to the individual. Tumour size and growth, hearing, age and general health, symptoms, and personal preferences all shape the decision, and the conversation is best had with a team that handles acoustic neuromas regularly.

Whichever path is chosen, long-term follow-up is part of the picture, and so is attention to hearing, balance, and facial function. Many people return to a full and active life after treatment, sometimes with the help of hearing devices, vestibular rehabilitation, or facial therapy. Understanding the options — what they involve, what they can and cannot do, and what to expect afterwards — is the foundation for the discussions ahead with your specialist.