What Is an Acoustic Neuroma?

An acoustic neuroma, also called an acoustic neurinoma or vestibular schwannoma, is a slow-growing, usually non-cancerous tumor that develops on the vestibular nerve. This nerve connects the inner ear to the brain and helps control balance. Because the tumor grows near the hearing and balance nerves, symptoms often include hearing loss, ringing in the ear (tinnitus), dizziness, and balance problems. Treatment is not the same for every person. The best approach depends on the size and growth rate of the acoustic tumor, the person's age and overall health, and whether hearing is still present.

Observation and Monitoring

Many acoustic neuromas grow very slowly, and some do not grow at all. For small tumors, or for older adults and people with other health conditions, a doctor may recommend a strategy of active surveillance, sometimes called "watch and wait" or "wait and scan." This is not a treatment to remove the tumor, but a plan to monitor it carefully with regular magnetic resonance imaging (MRI) scans and hearing tests. If the acoustic tumor shows no significant growth, treatment may be deferred for months or years. If symptoms worsen or the tumor begins to grow more quickly, active treatment can be reconsidered.

Surgery

Surgical removal is a common treatment for larger acoustic neuromas, tumors that are growing rapidly, or tumors that cause severe pressure on the brainstem. The goal of surgery is to remove the tumor while preserving, as much as possible, the function of the facial nerve and the hearing nerve.

Several surgical approaches are used, depending on the size and location of the tumor and the status of the person's hearing:

• Translabyrinthine approach: The surgeon reaches the tumor through the inner ear. This approach is often used for larger tumors and does not aim to preserve hearing, so it is typically chosen when hearing in the affected ear is already poor.
• Retrosigmoid approach: The surgeon accesses the tumor from behind the skull. This approach may allow hearing preservation in some cases and is used for tumors of various sizes.
• Middle fossa approach: The surgeon reaches the tumor through a small opening above the ear canal. This approach is usually reserved for small tumors and has the greatest potential for hearing preservation.

Like any operation, acoustic neuroma surgery carries risks. Possible complications include facial weakness or numbness, hearing loss, balance difficulties, cerebrospinal fluid leakage, infection, and rarely, injury to surrounding brain structures. The outcome depends greatly on the experience of the surgical team and the size of the acoustic tumor.

Radiation Therapy

Radiation is a less invasive option for many acoustic neuromas. The goal is not to remove the tumor but to stop its growth and, over time, shrink it. Radiation is often recommended for small to medium-sized tumors, for tumors that grow after surgery, or for people who cannot safely undergo general anesthesia and surgery.

Two main forms of radiation are used:

• Stereotactic radiosurgery: This delivers a precise, high dose of radiation to the acoustic tumor in a single session. It is performed with advanced imaging to target the tumor while limiting radiation to surrounding healthy tissue. Gamma Knife and CyberKnife systems are examples of this technology.
• Fractionated stereotactic radiotherapy: This delivers the radiation in smaller doses over several sessions. It may be preferred for larger tumors or tumors close to sensitive structures, as it spreads the radiation over time and may reduce damage to nearby nerves.

Radiation treatment does not require an incision and is generally done on an outpatient basis. Hearing may be preserved for a time, but it can gradually decline over the years following treatment. Other possible effects include temporary facial numbness, balance problems, or weakness, and there is a small risk that the tumor may continue to grow despite treatment. Regular follow-up imaging is needed after radiation to confirm that the acoustic neuroma remains stable.

Medication

Currently, there is no medication that is approved specifically to cure or remove a sporadic acoustic neuroma. Medication, however, can play an important role in managing symptoms and, in certain situations, in slowing tumor growth.

Symptom management: Drugs may be used to reduce dizziness, control pain, or treat anxiety. Corticosteroids are sometimes prescribed to reduce swelling and inflammation around the tumor, which may temporarily help with symptoms such as facial numbness or hearing changes. If hearing loss is present, no medication is currently available to restore it.

Tumor growth control in select cases: In people with neurofibromatosis type 2, a rare inherited condition associated with bilateral vestibular schwannomas (tumors on both sides), a medication called bevacizumab, which is a type of angiogenesis inhibitor, has been studied. In some of these cases, it has been shown to slow the growth of schwannomas and, in a minority of people, even improve hearing. This drug is not a standard treatment for the more common one-sided acoustic neuroma, and it is used only under the supervision of a specialized medical team because it can have serious side effects.

Patients should always discuss with their doctor whether any medication is appropriate for their specific condition, and no over-the-counter remedy or "alternative" drug has been proven to treat an acoustic tumor.

Factors That Guide Treatment Choice

The decision about whether to observe, operate, radiate, or use medication is highly individual. Important factors include:

• Size and growth rate: Small, stable tumors are often observed; large or growing tumors more often require surgery or radiation.
• Hearing status: If useful hearing remains, hearing-preserving approaches such as the retrosigmoid or middle fossa approach, or fractionated radiation, may be considered.
• Symptoms: Severe pressure symptoms, balance problems, facial numbness, or brainstem compression usually push toward active treatment.
• Age and general health: Older or frail individuals may tolerate observation or radiation better than surgery.
• Patient preference: Some people prefer to remove the tumor completely, while others prefer to avoid surgery and accept the need for ongoing scans.

Long-Term Outlook

With modern treatment, the outlook for people with an acoustic neuroma is generally excellent. Because these tumors are slow-growing and rarely become cancerous, most people can be managed successfully with observation, surgery, or radiation. Many people return to their normal activities, although hearing loss in the affected ear often persists. Lifelong follow-up with imaging is usually recommended to watch for recurrence or growth of the acoustic tumor. Every person should work closely with a health care team that includes ear, nose, and throat specialists, neurosurgeons, and radiation oncologists to choose the safest and most effective treatment plan.