Symptoms of an acoustic neuroma often are easy to miss and may take years to develop. Symptoms may occur because of the tumor's effects on the hearing and balance nerves. The tumor also can put pressure on the facial nerve that directs facial muscles and the trigeminal nerve that affects feeling in the face. Blood vessels or other brain structures also can be affected by an acoustic neuroma.

As the tumor grows, it may be more likely to cause more noticeable or worse symptoms.

Common signs and symptoms of an acoustic neuroma include:

• Hearing loss, usually gradually over months to years. In rare cases, hearing loss can be sudden. Hearing loss usually occurs on one side or is worse on one side.
• Ringing in the affected ear, known as tinnitus.
• Loss of balance or not feeling steady.
• Dizziness.
• Facial numbness and, very rarely, weakness or loss of muscle movement.

Rarely, an acoustic neuroma may grow large enough to compress the brainstem and become life-threatening.

When to see your doctor

See a healthcare professional if you notice hearing loss in one ear, ringing in your ear or trouble with balance.

Early diagnosis of an acoustic neuroma may help keep the tumor from growing large enough to cause complications such as total hearing loss.

The cause of acoustic neuromas can sometimes be linked to a change to a gene on chromosome 22. Typically, this gene produces a tumor suppressor protein that helps regulate the growth of Schwann cells covering the nerves. Experts don't know what causes this change to the gene. Often there is no known cause. In some people, the gene change is related to a rare condition called NF2-related schwannomatosis, also known as NF2. The condition was previously known as neurofibromatosis type 2. People with NF2 usually have growth of tumors on the hearing and balance nerves on both sides of the head. These tumors are known as bilateral vestibular schwannomas.

NF2-related schwannomatosis

The only confirmed risk factor for acoustic neuromas is having a parent with the rare genetic condition NF2-related schwannomatosis, also known as NF2. However, only a small number of people with acoustic neuromas have NF2.

A hallmark characteristic of NF2 is noncancerous tumors on the balance nerves on both sides of the head. Tumors also may develop on other nerves.

NF2 is known as an autosomal dominant condition. This means that the gene related to the condition can be passed to a child by just one parent. Each child of an affected parent has a 50-50 chance of inheriting it.

An acoustic neuroma may cause permanent complications, including:

• Hearing loss.
• Facial numbness and weakness.
• Trouble with balance.
• Ringing in the ear.

Large tumors may press on the brainstem, occasionally preventing the flow of cerebrospinal fluid between the brain and spinal cord. Fluid can build up in your head, a condition known as hydrocephalus. This increases the pressure inside the skull.

An acoustic neuroma often is hard to diagnose in the early stages because symptoms may be easy to miss and develop slowly over time. Common symptoms such as hearing loss also are associated with many other middle and inner ear issues.

After asking questions about your symptoms, a member of your healthcare team conducts an ear exam. You may need the following tests:

• Hearing test, known as audiometry. This test is conducted by a hearing specialist called an audiologist. During the test, sounds of various tones are directed to one ear at a time. You indicate each time you hear the sound. Each tone is repeated at fainter levels to find out when you can barely hear. The audiologist also may use words to test your hearing.
• Imaging. Magnetic resonance imaging (MRI) with contrast dye is usually used to diagnose an acoustic neuroma. This imaging test can detect tumors as small as 1 to 2 millimeters in diameter. If MRI is not available or you can't have an MRI scan, a CT scan may be done. However, CT scans may miss small tumors.

Your acoustic neuroma treatment may vary, depending on:

• The size and growth rate of the acoustic neuroma.
• Your overall health.
• Your signs and symptoms.

There are three treatment approaches for acoustic neuroma: monitoring, surgery or radiation therapy.

Monitoring

You and your healthcare team may decide to monitor an acoustic neuroma if it's small and isn't growing or if it's growing slowly. This may be an option if the acoustic neuroma causes few or no symptoms. Monitoring also may be recommended if you're an older adult or if you're not a good candidate for more-aggressive treatment.

While being monitored, you'll need regular imaging and hearing tests, usually every 6 to 12 months. These tests can determine whether the tumor is growing and how quickly. If the scans show the tumor is growing or if the tumor causes worse symptoms, you may need to have surgery or radiation.

Surgery

You may need surgery to remove an acoustic neuroma, especially if the tumor is:

• Continuing to grow.
• Very large.
• Causing symptoms.

Your surgeon may use one of several techniques for removing an acoustic neuroma. The type of surgery your surgeon chooses depends on the size of the tumor, your hearing status and other factors.

The goal of surgery is to remove the tumor and preserve the facial nerve to prevent the paralysis of muscles in your face. Removing the entire tumor may not always be possible. For example, if the tumor is too close to important parts of the brain or the facial nerve, only part of the tumor may be removed.

Surgery for an acoustic neuroma is performed under general anesthesia. Surgery involves removing the tumor through the inner ear or through a window in your skull.

Sometimes removing the tumor may worsen symptoms if the hearing, balance or facial nerves are irritated or damaged during the operation. Hearing may be lost on the side where the surgery is performed. Balance is usually affected temporarily.

Complications may include:

• Leaking of the fluid that surrounds your brain and spinal cord, known as cerebrospinal fluid. Leaking may happen through the wound.
• Hearing loss.
• Facial weakness or numbness.
• Ringing in the ear.
• Trouble with balance.
• Persistent headache.
• Rarely, infection of the cerebrospinal fluid, known as meningitis.
• Very rarely, stroke or brain bleeding.

Radiation therapy

There are several types of radiation therapy used to treat an acoustic neuroma:

• Stereotactic radiosurgery. This type of radiation therapy is often used if the tumor is small — less than 2.5 centimeters in diameter. It also may be used if you are an older adult or you cannot have surgery for health reasons. This technique uses many tiny gamma rays to deliver a precisely targeted dose of radiation to a tumor. It treats the tumor without making an incision or damaging surrounding tissue.

  The goal of stereotactic radiosurgery, such as Gamma Knife and CyberKnife, is to stop the growth of a tumor. The treatment also aims to preserve the facial nerve's function and possibly preserve hearing. It may take weeks, months or years before you notice the effects of radiosurgery. Your healthcare team monitors your progress with follow-up imaging studies and hearing tests.

  Risks of radiosurgery include:

  • Hearing loss.
  • Ringing in the ear.
  • Facial weakness or numbness.
  • Trouble with balance.
  • Continued tumor growth.
• Fractionated stereotactic radiotherapy. Fractionated stereotactic radiotherapy, also called SRT, delivers a small dose of radiation to the tumor over several sessions. SRT is done to slow the growth of the tumor without damaging surrounding brain tissue.
• Proton beam therapy. This type of radiation therapy uses high-energy beams of positively charged particles called protons. The proton beams are delivered to the affected area in targeted doses to treat tumors. This type of therapy lowers radiation exposure to the surrounding area.

Supportive therapy

In addition to treatment to remove or stop the growth of the tumor, supportive therapies can help reduce your symptoms. The therapies help with dizziness, trouble with balance or other complications. For hearing loss, you can use cochlear implants or other treatments.

Dealing with the possibility of hearing loss and facial paralysis can be quite stressful. Deciding which treatment would be best for you also can be challenging. These suggestions may help:

• Educate yourself about acoustic neuromas. The more you know, the better prepared you can be to make choices about treatment. Besides talking to your healthcare team and your audiologist, you may want to talk to a counselor or social worker. Or you may find it helpful to talk to other people who've had an acoustic neuroma. It may help to learn more about their experiences during and after treatment.
• Maintain a strong support system. Family and friends can help you as you go through this challenging time. You also might find the concern and understanding of other people with an acoustic neuroma especially comforting. Your healthcare team or a social worker may be able to put you in touch with a support group. Or you can find an in-person or online support group through the Acoustic Neuroma Association.

You first may see a healthcare professional. This person may refer you to a doctor trained in ear, nose and throat conditions. Or you may be referred to a doctor trained in brain and nervous system surgery, known as a neurosurgeon. Here's some information to help you get ready for your appointment.

What you can do

• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Make a list of all medicines, vitamins or supplements that you're taking.
• Ask a family member or friend to join you, if possible. Sometimes it can be hard to remember all the information provided to you during an appointment. Someone who comes with you may remember something that you missed or forgot.
• Write down questions to ask your healthcare team.

Preparing a list of questions will help you make the most of your time. For an acoustic neuroma, some basic questions to ask include:

• What is likely causing my symptoms?
• Are there any other possible causes for my symptoms?
• What kinds of tests do I need?
• What treatment options are available?
• Which one do you recommend for me?
• What is the likelihood of side effects from each treatment option?
• What happens if I do nothing?
• Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

In addition to the questions that you've prepared, don't hesitate to ask any that come up during your appointment.

What to expect from your doctor

You'll be asked some questions. Being ready to answer them can give you more time to go over any points that you need to clarify. You may be asked:

• When did you first begin experiencing symptoms?
• Have your symptoms been constant or off and on?
• How bad are your symptoms?
• Do you have any family members with an acoustic neuroma?
• At its current level, can you hear using the affected ear? For example, can you use that ear on the phone? Does that ear help you tell where sound is coming from?
• Do you have regular headaches currently or have you had them in the past?