Acoustic neuroma, also known as vestibular schwannoma, is a noncancerous and usually slow-growing tumor that develops on the main (vestibular) nerve leading from your inner ear to your brain. Branches of this nerve directly influence your balance and hearing, and pressure from an acoustic neuroma can cause hearing loss, ringing in your ear and unsteadiness.
Acoustic neuroma usually arises from the Schwann cells covering this nerve and grows slowly or not at all. Rarely, it may grow rapidly and become large enough to press against the brain and interfere with vital functions.
Treatments for acoustic neuroma include regular monitoring, radiation and surgical removal.
Acoustic neuroma care at Mayo Clinic
Signs and symptoms of acoustic neuroma are often subtle and may take many years to develop. They usually arise from the tumor's effects on the hearing and balance nerves. Pressure from the tumor on adjacent nerves controlling facial muscles and sensation (facial and trigeminal nerves), nearby blood vessels, or brain structures may also cause problems.
As the tumor grows, it may be more likely to cause more noticeable or severe signs and symptoms.
Common signs and symptoms of acoustic neuroma include:
In rare cases, an acoustic neuroma may grow large enough to compress the brainstem and become life-threatening.
See your doctor if you notice hearing loss in one ear, ringing in your ear or trouble with your balance.
Early diagnosis of an acoustic neuroma may help keep the tumor from growing large enough to cause serious consequences, such as total hearing loss or a life-threatening buildup of fluid within your skull.
The cause of acoustic neuromas appears to be a malfunctioning gene on chromosome 22. Normally, this gene produces a tumor suppressor protein that helps control the growth of Schwann cells covering the nerves.
What makes this gene malfunction isn't clear, and in most cases of acoustic neuroma, there is no identifiable cause. This faulty gene is also inherited in neurofibromatosis type 2, a rare disorder that usually involves the growth of tumors on balance nerves on both sides of your head (bilateral vestibular schwannomas).
Acoustic neuroma is often difficult to diagnose in the early stages because signs and symptoms may be subtle and develop gradually over time. Common symptoms such as hearing loss are also associated with many other middle and inner ear problems.
After asking questions about your symptoms, your doctor will conduct an ear exam. Your doctor may order the following tests:
Hearing test (audiometry). In this test, conducted by a hearing specialist (audiologist), you hear sounds directed to one ear at a time. The audiologist presents a range of sounds of various tones and asks you to indicate each time you hear the sound. Each tone is repeated at faint levels to find out when you can barely hear.
The audiologist may also present various words to determine your hearing ability.
An acoustic neuroma may cause a variety of permanent complications, including:
Large tumors may press on your brainstem, preventing the normal flow of fluid between your brain and spinal cord (cerebrospinal fluid). In this case, fluid can build up in your head (hydrocephalus), increasing the pressure inside your skull.
Dealing with the possibility of hearing loss and facial paralysis and deciding which treatment would be best for you can be quite stressful. Here are some suggestions you may find helpful:
Your doctor or a social worker may be able to put you in touch with a support group. Or you may find an in-person or online support group through the Acoustic Neuroma Association.
The only confirmed risk factor for acoustic neuroma is having a parent with the rare genetic disorder neurofibromatosis type 2. But neurofibromatosis type 2 only accounts for about 5 percent of acoustic neuroma cases.
A hallmark characteristic of neurofibromatosis type 2 is the development of noncancerous tumors on the balance nerves on both sides of your head, as well as on other nerves.
Neurofibromatosis type 2 (NF2) is known as an autosomal dominant disorder, meaning that the mutation can be passed on by just one parent (dominant gene). Each child of an affected parent has a 50-50 chance of inheriting it.