Schwannoma

Schwannoma is a type of nerve tumor of the nerve sheath. It is the most common type of benign peripheral nerve tumor in adults. It can occur in any part of your body, at any age.

A schwannoma typically consists of a single bundle (fascicle) within the main nerve and displaces the rest of the nerve. When a schwannoma grows, more fascicles are affected, making it more difficult to remove. In general, schwannoma grows slowly.

If a schwannoma develops on an arm or leg, you may notice a painless lump. Schwannomas are rarely malignant. However, they can lead to nerve damage and paralysis. If you have unusual swelling or numbness, you should consult your doctor.

Acoustic neuroma, also known as vestibular schwannoma, is a non-malignant and usually slow-growing tumor that develops on the main (vestibular) nerve that runs from your inner ear to your brain. The branches of this nerve directly affect your balance and hearing, and the pressure from an acoustic neuroma can cause hearing loss, ringing in your ears, and imbalance.

An acoustic neuroma usually arises from the Schwann cells lining this nerve and grows slowly or does not grow at all. Rarely, it can grow rapidly and become large enough to put pressure on the brain and interfere with vital functions.

Diagnosis

To diagnose a schwannoma, your doctor may ask you about signs and symptoms, question your medical history, and perform a general physical and neurological exam. If symptoms suggest you may have a schwannoma or other nerve tumor, your doctor may recommend one or more of the following diagnostic tests:

Magnetic resonance imaging (MRI). This scan uses a magnet and radio waves to produce a detailed, 3D view of your nerves and surrounding tissues.

Computed tomography (CT). A CT scanner rotates around your body to record a series of images. A computer uses the images to get a detailed view of your growth so your doctor can evaluate how it might affect you.

Electromyogram (EMG). For this test, your doctor inserts small needles into your muscles so an electromyography instrument can record the electrical activity in your muscle as you try to move it.

Nerve conduction study. You are likely to have this test with your EMG. It measures how quickly your nerves transmit electrical signals to your muscles.

Tumor biopsy. If imaging tests detect a nerve tumor, your doctor may take a small sample of cells (biopsy) from your tumor and analyze it. Depending on the size and location of the tumor, you may need local or general anesthesia during the biopsy.

Nerve biopsy. If you have a condition such as progressive peripheral neuropathy or enlarged nerves that mimic nerve tumors, your doctor may perform a nerve biopsy.

Treatment

Schwannoma treatment depends on where the abnormal growth is and whether it is causing pain or growing rapidly. Treatment options include:

Monitoring. Your doctor may suggest that you monitor your condition over time. Observation may include regular checkups and a CT or MRI scan every few months to see if your tumor is growing.

Operation. An experienced peripheral neurosurgeon can remove the tumor if it is causing pain or is growing rapidly. Schwannoma surgery is performed under general anesthesia. Depending on the location of the tumor, some patients may go home on the day of surgery. Others may need to stay in the hospital for a day or two. A tumor can recur even after successful removal of the tumor during surgery.

Radiation therapy. Radiation therapy is used to help control tumor growth and improve your symptoms. It can be used with surgery.

Stereotactic radiosurgery. If the tumor is close to vital nerves or blood vessels, a technique called stereotactic body radiation therapy may be used to limit damage to healthy tissue. With this technique, doctors deliver radiation exactly to a tumor without making an incision.