What Is an Acoustic Neuroma and How Is It Treated

What Is an Acoustic Neuroma and How Is It Treated

Introduction

Discovering you have a growth on your auditory nerve can be confronting. An acoustic neuroma—also known as a vestibular schwannoma—is a benign (non-cancerous) tumour that develops on the nerve connecting your inner ear to your brain. Whilst this diagnosis naturally raises concerns, understanding what it means and your options can help you feel more in control.

This comprehensive guide explains acoustic neuroma symptoms, how it's diagnosed, and the treatment pathways available. We'll explore how audiologists and medical specialists work together to support people with this condition, and what you can expect if you or someone you care about receives this diagnosis.

What Is an Acoustic Neuroma?

An acoustic neuroma is a benign tumour that grows slowly on the vestibular nerve—the nerve responsible for balance and hearing. Despite being called an "acoustic" neuroma, it actually develops on the vestibular portion of the eighth cranial nerve rather than the acoustic (hearing) portion.

Understanding the Basics

Key characteristics:

• Benign growth: Not cancerous and doesn't spread to other parts of the body
• Slow-growing: Typically grows 1-2mm per year, though growth rates vary
• Location: Develops in the internal auditory canal between the inner ear and brain
• Rare condition: Affects approximately 1 in 100,000 people annually in Australia
• Age factor: Most commonly diagnosed in adults aged 30-60 years

The tumour arises from Schwann cells—specialised cells that form the protective coating around nerves. As it grows, it can press against the hearing nerve, the balance nerve, and potentially nearby structures in the brain.

Types of Acoustic Neuroma

Most acoustic neuromas occur spontaneously with no clear cause. However, about 5% of cases are associated with a genetic condition called neurofibromatosis type 2 (NF2), which can cause tumours to develop on both sides.

Unilateral acoustic neuroma:

• Develops on one side only (95% of cases)
• Typically occurs sporadically
• Usually diagnosed in people over 30

Bilateral acoustic neuroma:

• Affects both sides (5% of cases)
• Associated with NF2 genetic condition
• Often diagnosed in younger individuals
• May have family history

Symptoms to Watch For

Acoustic neuroma symptoms develop gradually as the tumour grows. Because the growth is typically slow, many people don't notice symptoms immediately, and some small tumours are discovered incidentally during brain scans for other reasons.

Early Warning Signs

The most common early symptoms relate to hearing and balance, as the tumour affects the eighth cranial nerve:

Hearing changes:

• Gradual hearing loss in one ear (most common first symptom)
• Difficulty understanding speech, especially in noisy environments
• Hearing loss that may fluctuate initially
• Difference in hearing between the two ears
• Difficulty hearing high-pitched sounds

Tinnitus (ringing in the ears):

• Usually affects one ear only
• May be high-pitched ringing, buzzing, or hissing
• Can be constant or intermittent
• May be more noticeable in quiet environments

Balance problems:

• Feeling unsteady or off-balance
• Dizziness or vertigo (less common than hearing loss)
• Clumsiness or difficulty with coordination
• Sensation of the room spinning

Progressive Symptoms

As an acoustic neuroma grows larger, it may cause additional symptoms by pressing on surrounding structures:

Facial nerve symptoms:

• Facial numbness or tingling
• Facial weakness (in advanced cases)
• Changes in taste sensation
• Difficulty closing one eye completely

Pressure symptoms:

• Headaches (if tumour is large)
• Difficulty swallowing (rare)
• Pressure sensation in the ear

When to Seek Assessment

Contact your GP if you experience:

• Hearing loss in one ear, especially if gradual or persistent
• Persistent tinnitus in one ear
• New onset balance problems
• Unexplained facial numbness or weakness

Important: Whilst these symptoms can have many causes, one-sided hearing loss or tinnitus should always be professionally evaluated. Early assessment can help identify the cause and determine appropriate next steps.

How Acoustic Neuroma Is Diagnosed

Diagnosing an acoustic neuroma involves several steps, starting with your GP and progressing to specialist assessment and imaging.

Initial Assessment

Step 1: General practitioner consultation

Your GP will:

• Take your medical history
• Conduct a physical examination
• Assess your symptoms and their progression
• Perform basic hearing and balance tests
• Refer you to appropriate specialists

Step 2: Audiological assessment

A comprehensive hearing evaluation by an audiologist includes:

• Pure tone audiometry: Measures hearing thresholds across frequencies
• Speech discrimination testing: Assesses ability to understand words
• Tympanometry: Evaluates middle ear function
• Acoustic reflex testing: Measures automatic muscle responses to sound
• Otoacoustic emissions (OAE): Tests inner ear hair cell function

These tests help establish baseline hearing levels and identify patterns consistent with retrocochlear (beyond the cochlea) pathology, which may indicate an acoustic neuroma.

Specialist Evaluation

ENT (Ear, Nose and Throat) specialist assessment:

An ENT specialist will:

• Review your symptoms and hearing test results
• Examine your ears, nose and throat
• Conduct additional clinical tests
• Order appropriate imaging if acoustic neuroma is suspected
• Coordinate further specialist referrals if needed

Diagnostic Imaging

MRI (Magnetic Resonance Imaging):

MRI is the gold standard for diagnosing acoustic neuroma:

• Provides detailed images of soft tissues including nerves and tumours
• Can detect tumours as small as 2-3mm
• Uses contrast dye (gadolinium) for enhanced visualisation
• Non-invasive and painless procedure
• Typically takes 30-60 minutes

CT scan (Computed Tomography):

Occasionally used when MRI is not suitable:

• Provides detailed bone structure images
• Useful for surgical planning
• May be used if MRI is contraindicated
• Less sensitive than MRI for small tumours

Additional Testing

Auditory Brainstem Response (ABR):

This specialised hearing test:

• Measures electrical activity along the hearing pathway
• Can detect abnormalities in nerve signal transmission
• Helpful when MRI access is limited
• Performed by audiologists or neurologists

Once acoustic neuroma is confirmed, your medical team will assess the tumour's size, location, and growth characteristics to determine the most appropriate management approach.

Treatment Options for Acoustic Neuroma

Treatment for acoustic neuroma depends on multiple factors including tumour size, growth rate, symptoms, your age, overall health, and personal preferences. The three main approaches are active monitoring, surgical removal, and radiation therapy.

Active Monitoring (Watch and Wait)

For small, slow-growing tumours with minimal symptoms, active monitoring may be recommended.

What it involves:

• Regular MRI scans (typically every 6-12 months initially)
• Ongoing hearing assessments
• Symptom monitoring
• No immediate intervention

Who it suits:

• Small tumours (typically under 1.5cm)
• Minimal or manageable symptoms
• Slow or no growth on serial scans
• Older individuals or those with health concerns that increase surgical risk
• Personal preference for conservative approach

Advantages:

• Avoids surgery and associated risks
• Suitable if tumour isn't causing significant problems
• Many small tumours grow very slowly or not at all

Considerations:

• Requires regular monitoring
• Symptoms may gradually worsen
• Tumour may eventually require treatment
• Ongoing uncertainty for some individuals

Surgical Removal

Surgery aims to completely remove the acoustic neuroma whilst preserving hearing and facial nerve function where possible.

Surgical approaches:

Different surgical techniques are used depending on tumour size and location:

1. Translabyrinthine approach

• Removes tumour through the mastoid bone
• Provides excellent access to larger tumours
• Hearing in affected ear is sacrificed
• Lower risk to facial nerve

2. Retrosigmoid approach

• Accesses tumour from behind
• May preserve hearing in some cases
• Used for medium to large tumours
• Good visualisation of facial nerve

3. Middle fossa approach

• Approaches from above
• Best chance of hearing preservation
• Suitable for small tumours in specific locations
• More technically demanding

Surgery considerations:

• Performed by neurosurgeon, sometimes with ENT surgeon
• Requires general anaesthesia
• Hospital stay typically 3-7 days
• Recovery period of several weeks to months
• Results vary based on tumour size, location and individual factors

Potential outcomes:

• Complete tumour removal (goal in most cases)
• Partial removal if complete removal poses risks
• Hearing preservation success depends on multiple factors
• Facial nerve preservation prioritised but not always possible

Radiation Therapy

Radiation therapy uses precisely targeted radiation to stop tumour growth without surgery.

Stereotactic radiosurgery (SRS):

Despite the name "radiosurgery," this is not surgery but highly focused radiation:

Gamma Knife:

• Delivers radiation from multiple angles
• Single treatment session
• Outpatient procedure
• Head frame fitted for precise targeting

Linear accelerator (LINAC) systems:

• Similar principle to Gamma Knife
• May use frameless targeting
• Sometimes delivered over multiple sessions (fractionated stereotactic radiotherapy)

Who it suits:

• Small to medium tumours (typically under 3cm)
• Those unable to undergo surgery
• Tumour in location making surgery high-risk
• Patient preference for non-surgical approach
• Elderly individuals

How it works:

• Radiation damages tumour DNA, stopping growth
• Tumour typically stops growing or shrinks slowly over months to years
• Preserves facial nerve function in most cases
• Hearing outcomes vary

Considerations:

• Tumour remains in place (not removed)
• May take months to years to see full effect
• Small risk of radiation side effects
• Long-term monitoring still required
• Rarely, tumour may eventually require surgery

Choosing the Right Approach

Your medical team will consider:

• Tumour size and growth rate
• Current symptoms and hearing level
• Your age and overall health
• Personal goals and preferences
• Risks and benefits of each option

Important: Treatment decisions for acoustic neuroma should be made in consultation with experienced neurosurgeons, ENT specialists, and radiation oncologists. Individual results vary, and there is no one-size-fits-all approach.

Living with Acoustic Neuroma

Whether you're undergoing active monitoring or have had treatment, living with acoustic neuroma involves ongoing support and adaptation.

Managing Hearing Changes

If hearing is affected:

• Comprehensive hearing assessment by audiologist
• Hearing aids may help if hearing loss is manageable
• CROS or BiCROS hearing systems for single-sided deafness
• Bone-anchored hearing aids (BAHA) in some cases
• Communication strategies and support

Balance Rehabilitation

Vestibular rehabilitation therapy:

Specialised physiotherapy can help with balance issues:

• Exercises to improve balance and coordination
• Strategies to reduce dizziness
• Adaptation techniques for daily activities
• Conducted by physiotherapists with vestibular training

Emotional Support

Psychological considerations:

An acoustic neuroma diagnosis can be emotionally challenging:

• Uncertainty about tumour growth and symptoms
• Decisions about treatment options
• Adjustment to hearing or balance changes
• Concerns about facial nerve function
• Impact on work and daily life

Support available:

• Counselling services
• Support groups (Acoustic Neuroma Association Australia)
• Connecting with others who've experienced similar diagnoses
• Family and carer support

Ongoing Monitoring

Follow-up care:

Regardless of treatment approach:

• Regular MRI scans to monitor tumour status
• Ongoing hearing assessments
• Clinical examinations
• Symptom review
• Adjustment of management plan as needed

Practical Considerations

Daily life adaptations:

Many people continue normal activities with acoustic neuroma:

• Most can continue working (adjustments may be needed)
• Safe participation in most daily activities
• Consideration for activities involving balance if affected
• Communication strategies for hearing challenges
• Driving usually unaffected unless balance is significantly impaired

The Role of Audiologists in Acoustic Neuroma Care

Audiologists play an important role throughout the acoustic neuroma journey, from initial detection to ongoing management.

Diagnostic Phase

Early detection:

• Comprehensive hearing assessments that may detect patterns suggesting retrocochlear pathology
• Identification of asymmetric hearing loss requiring further investigation
• Specialised testing (ABR, acoustic reflex) that can indicate nerve involvement
• Collaboration with ENT specialists for appropriate imaging referrals

Pre-Treatment Assessment

Baseline documentation:

• Detailed hearing measurements before treatment
• Speech understanding capabilities
• Balance system function
• Documentation for comparison with post-treatment results

Treatment Decision Support

Informing choices:

• Explaining hearing preservation likelihood with different treatment approaches
• Discussing hearing rehabilitation options if hearing loss occurs
• Providing realistic expectations about auditory outcomes
• Answering questions about hearing-related aspects of treatment

Post-Treatment Rehabilitation

Ongoing hearing care:

After treatment, audiologists assist with:

Hearing loss management:

• Assessment of hearing changes
• Hearing aid fitting and adjustment if appropriate
• CROS/BiCROS systems for single-sided deafness
• BAHA assessment and programming if recommended
• Cochlear implant evaluation in specific cases

Communication strategies:

• Techniques for managing single-sided hearing
• Environmental modifications for better communication
• Counselling on hearing loss adaptation
• Family education about communication support

Monitoring and support:

• Regular hearing assessments to track changes
• Tinnitus management strategies if needed
• Coordination with medical team for ongoing care
• Support throughout the adaptation process

Australian Context

In Australia, audiologists work within the healthcare system:

• Some services covered by Medicare (MBS items for specific assessments)
• Private health insurance may cover some audiological care
• Public hospital audiology services available
• Private practice options for comprehensive ongoing care

References and Further Information

Australian resources:

• Acoustic Neuroma Association of Australia (ANAA)
• Better Health Channel (Victoria State Government)
• Health Direct Australia
• Royal Australian College of Surgeons
• Neurosurgical Society of Australasia

Medical organisations:

• Australian Society of Otolaryngology Head and Neck Surgery (ASOHNS)
• Audiology Australia
• Australian and New Zealand Association of Neurologists

International resources:

• Acoustic Neuroma Association (USA)
• British Acoustic Neuroma Association

Important: Use these resources for general information only. For personalised advice regarding diagnosis, treatment, or management of acoustic neuroma, consult qualified medical professionals including ENT specialists, neurosurgeons, and audiologists.