Benign Tumors of the Hearing Nerve (Acoustic Neuromas)

Acoustic neuroma, also known as vestibular schwannoma, is a noncancerous and usually slow-growing tumor that develops on the main 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 is caused by 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.

Signs and symptoms

Signs and symptoms of acoustic neuroma are often easy to miss and may take many years to develop. They usually happen because of the tumor's effects on the hearing and balance nerves. Pressure from the tumor on nearby nerves controlling facial muscles and sensation, nearby blood vessels, or brain structures may also cause problems. As the tumor grows, it may cause more noticeable or severe signs and symptoms.

Common signs and symptoms of acoustic neuroma include:

• Hearing loss, usually gradually worsening over months to years — although in rare cases sudden — and occurring on only one side or more severe on one side
• Ringing (tinnitus) in the affected ear
• Unsteadiness or loss of balance
• Dizziness (vertigo)
• Facial numbness and weakness or loss of muscle movement

Treatment

To treat acoustic neuroma, your doctor may suggest one or more of three potential options: monitoring, surgery or radiation therapy.

Monitoring

If you have a small acoustic neuroma that isn't growing or is growing slowly and causes few or no signs or symptoms, you and your doctor may decide to monitor it. Monitoring may be recommended if you're an older adult or otherwise not a good candidate for more aggressive treatment.

Surgery

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

• Continuing to grow
• Very large
• Causing symptoms

The goal of surgery is to remove the tumor and preserve the facial nerve to prevent facial paralysis. Removing the entire tumor may not be possible in certain cases — for example, if the tumor is too close to important parts of the brain or the facial nerve.

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

Radiation therapy

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

• Stereotactic radiosurgery. Your doctor may recommend a type of radiation therapy known as stereotactic radiosurgery. It's often used if your tumor is small (less than 2.5 centimeters in diameter), you are an older adult or you cannot tolerate surgery for health reasons.
  Stereotactic radiosurgery, such as Gamma Knife radiosurgery, uses many tiny gamma rays to deliver a precisely targeted dose of radiation to a tumor without damaging the surrounding tissue or making an incision.
• Stereotactic radiotherapy. Fractionated stereotactic radiotherapy (SRT) delivers a small dose of radiation to the tumor over several sessions. SRT is done to curb 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. Protons are delivered to the affected area in targeted doses to treat tumors and minimize radiation exposure to the surrounding area.