What is an acoustic neuroma?
An acoustic neuroma, also called a vestibular schwannoma, is a non-cancerous tumor that occurs around your balance and hearing nerves that connect your inner ear with your brain.
The term schwannoma means the tumor developed from Schwann cells. These cells surround nerves in the peripheral nervous system (nerves outside the brain and spinal cord) and normally insulate and support the function of nerves. Schwannomas can occur in nerves across the body, but in the head, these most commonly occur from the vestibular nerve, or balance nerve.
Is an acoustic neuroma cancer?
An acoustic neuroma is a benign tumor (not cancer). Benign tumors do not spread to other parts of the body the way cancerous tumors do. They cause problems by growing and pressing on important structures and nerves. These tumors tend to grow slowly, sometimes over many years.
How does an acoustic neuroma affect people?
The tumor can cause symptoms most commonly by affecting hearing or balance functions. More than 90% of acoustic neuromas affect the hearing nerve in one ear, which is called unilateral hearing loss.
An acoustic neuroma can also press on nerves that control your facial movement, sensation and expression. Large tumors that press on brain structures that control the flow of spinal fluid out of the brain can be life-threatening.
What is the difference between an acoustic neuroma and a vestibular schwannoma?
An acoustic neuroma and a vestibular schwannoma are the same condition. Vestibular schwannoma is the technically proper term because it more accurately describes the type of tumor (schwannoma) and the nerve it originates from (vestibular nerve).
How common is an acoustic neuroma?
Acoustic neuromas are considered rare. Every year, about one out of every 100,000 people develops an acoustic neuroma. Unilateral (one-sided) acoustic neuromas represent about 8% of all skull tumors.
Who might get an acoustic neuroma?
While anyone can develop an acoustic neuroma, some populations are at higher risk. They occur more commonly with increasing age, peaking in those aged between 65 and 74. (Acoustic neuromas are very rare in children.) They occur equally among men and women. Asian Americans have the highest incidence, followed by White, and then Black Americans.
Typically, acoustic neuromas affect the hearing nerve in only one ear. Acoustic neuromas might affect both ears in people with neurofibromatosis type 2 (NF2), a genetic disorder. People with NF2 represent about 5% of people with acoustic neuromas.
Symptoms and Causes
What causes an acoustic neuroma?
Researchers do not know why acoustic neuromas form. Most of the time, the tumors arise spontaneously — with no known cause or reason. For a small group of people, the acoustic neuroma develops as part of NF2.
What are the symptoms of an acoustic neuroma?
The most common symptom is hearing loss in one ear (unilateral). This symptom happens to about 90% of people who have an acoustic neuroma.
Other symptoms that may occur in the early stages include:
- Ringing in the ears (tinnitus).
- Loss of balance.
- Sensation that you or your environment is moving (vertigo).
As the tumor grows, you may have other symptoms, including:
- Blurry or double vision.
- Facial numbness, weakness, spasms, pain, or paralysis.
- Taste changes.
- Nausea and vomiting.
- Swallowing difficulty.
Symptoms of acoustic neuromas can mimic symptoms of other ear problems. This similarity makes it challenging to diagnose an acoustic neuroma. Talk to your healthcare provider if you notice any hearing changes.
Diagnosis and Tests
How is an acoustic neuroma diagnosed?
Your healthcare provider will ask you about your symptoms and perform a physical exam. You will also have a series of hearing and balance tests and scans, which may include:
- Audiogram to check hearing ability.
- Electronystagmography, which tests balance and records eye movement to check how your eye and ear nerves are functioning.
- Auditory brainstem response to measures how hearing nerves response to sound and check brainstem function.
- MRI and CT scans to locate the tumor and measure its size.
Management and Treatment
What are treatment options for an acoustic neuroma?
Your healthcare provider will discuss your treatment options with you. Your treatment plan will depend on:
- Tumor size and location.
- Your age and overall health.
- Degree of damage to your hearing and balance nerves.
Treatment options include:
- Observation: If the tumor is small, not growing and not causing any symptoms, your healthcare provider may recommend monitoring the tumor but not actively treating it. You will have regular MRI scans to see if the tumor is growing. If it does grow or cause symptoms, your provider can quickly switch to active treatment.
- Radiosurgery: For small and medium tumors, this approach may stop tumor growth. You receive a single high dose of targeted radiation therapy, delivered directly to the tumor. This approach limits the amount of radiation that affects surrounding, healthy tissues. You will need ongoing scans during treatment to watch for any tumor growth.
- Microsurgery: This type of surgery uses instruments designed to operate on small, delicate areas. The goal is to remove as much of the acoustic neuroma as possible while preserving your facial nerve function. Surgery is the only treatment option that permanently removes the tumor. In some cases, surgeons can preserve your hearing, though not always. The smaller the tumor, the more likely it can be removed and hearing preserved.
How will the surgeon decide if I need surgery?
Generally, your care team will recommend surgery for an acoustic neuroma if the tumor is:
- Growing quickly.
- Causing symptoms.
- Potentially life-threatening.
What is surgery like for an acoustic neuroma?
There are three surgical options for removing an acoustic neuroma. Sometimes, surgeons can remove the entire tumor. Other times, they may choose to leave a small portion of the tumor in order to preserve the function of the facial nerve.
Your surgical team will discuss which approach works best for your needs:
- Middle fossa approach (best for small tumors inside the bony ear canal): The surgeon accesses the inner ear through an incision on the side of the head. The surgeon then separates the tumor from the nerves and removes it. This approach may preserve your facial nerve and hearing nerve.
- Retrosigmoid approach (often used for medium to large tumors that press on the brain): The surgeon accesses the tumor through an incision behind the ear. Then the surgeon removes any part of the tumor in the cranial fossa (part of the skull) and inner ear canal. This approach may prevent facial paralysis. It might even preserve hearing.
- Translabyrinthine approach (used to remove tumors of all sizes): The surgeon makes an incision behind the ear, removing bones of the inner ear for a better view of the tumor. The surgeon removes the tumor. This surgery results in total hearing loss on the side of the surgery. Surgeons typically use it only if you have already lost hearing on that side. This approach has excellent outcomes in preserving the facial nerve.
How does the surgeon preserve facial nerve function during acoustic neuroma surgery?
The surgical team monitors your facial nerve function during surgery. Surgeons use specialized equipment to map the location of the critical nerves near the tumor. This technology alerts the surgeon if the surgery is affecting the facial nerve and the surgeon can test the function of the nerve throughout the surgery.
Can the surgeon preserve my hearing?
Your surgeon monitors your hearing during surgery to increase the chances of hearing preservation.
People with large tumors that have seriously affected hearing have a lower chance of preserved hearing. About 50% of people who have small to medium tumors and good hearing before surgery will hear in that ear after surgery.
What can I expect after surgery for an acoustic neuroma?
After surgery, you will likely stay two to three nights in the hospital. In most cases, you will not need to be in an intensive care unit (ICU). After surgery, you may feel some head discomfort and fatigue. Most patients will go home after the hospital and we recommend everyone undergo outpatient physical therapy focused on balance exercises.
You will need follow-up care, including:
- Tests to check your hearing, balance and facial nerve function.
- Rehabilitation, in some cases, to improve balance.
- MRI scans to confirm the tumor has been completely removed.
- Imaging scans after surgery to monitor the area.
Are there post-surgical complications after acoustic neuroma surgery?
Your care team will discuss possible post-surgical complications and how to treat and manage them. Issues that may arise after surgery include:
- Hearing loss in one ear due to tumor removal surgery.
- Tumor growing back.
- Tinnitus (ringing in the ear).
- Cerebrospinal fluid (CSF) leaks.
- Infection of the incision or meningitis.
- Dizziness, balance problems, headaches.
- Weak facial nerve, or temporary or permanent facial paralysis.
- Eye issues (dry eyes, double vision, difficulty closing eyelid).
- Taste issues, dry mouth, trouble swallowing.
Will I need rehabilitation after acoustic neuroma surgery?
Sometimes, during tumor removal surgery, the surgeon needs to remove sections of the nerves that control balance. If that happens, you may experience dizziness and balance problems.
Vestibular rehabilitation helps you improve your balance and reduce dizziness. It works by training your central nervous system and the balance center on the other side to compensate for the vestibular nerves removed from the inner ear and take over its functions.
Can acoustic neuromas be prevented?
You cannot prevent acoustic neuromas from developing. But you can reduce your risk of complications by paying attention to how you feel and function. If you notice any symptoms such as hearing loss, dizziness or ringing in your ears, don’t dismiss your concerns.
Talk to your healthcare provider who can perform a full diagnosis and get to the bottom of your symptoms. The earlier an acoustic neuroma is detected, the better the chances for full tumor removal and hearing preservation.
Outlook / Prognosis
Will the acoustic neuroma return after surgery?
There is a chance of recurrence (a tumor that grows back after treatment). You will undergo regular monitoring after treatment so your provider can detect and treat recurrence as soon as possible.
Can hearing loss be restored after removing an acoustic neuroma?
Sometimes, you may lose your hearing as a result of the tumor or surgery. In those cases, you usually can't regain your hearing. Your healthcare provider can talk to you about devices that can help if you lost hearing in one ear. These include:
- CROS (contralateral routing of sound) aid: A microphone-like device worn on both sides. It takes sound received from the non-hearing ear and sends it to the hearing ear.
- Bone conduction hearing implant: Surgeons anchor this device into the skull behind the non-hearing ear. The implant sends sound waves from the non-hearing ear to the hearing ear.
- Auditory brainstem implant: This option is for people who have neurofibromatosis. Surgeons place the implant directly on the hearing centers of the brain, restoring some hearing function.
When should I see my doctor about an acoustic neuroma?
If you notice changes in your hearing, balance issues or dizziness, talk to your healthcare provider. Several ear conditions can cause these symptoms. The sooner you get the right care, the sooner you can feel better and return to your daily life.
What should I ask my doctor?
If you have an acoustic neuroma, consider asking your healthcare provider:
- Do I need treatment for the acoustic neuroma?
- What outcome can I expect if I have surgery?
- What complications am I at risk for from treatment?
- What is the chance I’ll have hearing in my ear?
- How likely is it that the acoustic neuroma will come back?
- Am I higher risk for other types of tumors?
- What are the risks and benefits of acoustic neuroma surgery?
- Will I need rehabilitation after surgery?
A note from Cleveland Clinic
Acoustic neuromas are slow-growing, benign (noncancerous) tumors that can cause hearing loss in one ear, dizziness and balance problems. Treatment options include observation (waiting to see if the tumor grows), focused radiation therapy and surgery. Surgeons work carefully to preserve facial nerve function and hearing when possible. Rehabilitation after surgery can help you restore your balance, and hearing devices can help with hearing loss.