Mayo Clinic Care Network Content
Diseases and Conditions

Schwannoma

Symptoms

The symptoms and signs of a peripheral nerve tumor develop from direct effects on the main nerve or from the tumor pressing on nearby nerves, blood vessels or tissues. As the tumor grows, it may be more likely to cause signs and symptoms, although tumor size doesn't always determine effects.

Signs and symptoms of peripheral nerve tumors vary depending on the location of the tumors and which tissues are affected. They include:

  • Swelling or a lump under your skin
  • Pain, tingling or numbness
  • Weakness or loss of function in the affected area
  • Dizziness or loss of balance

When to see a doctor

See your doctor when you have any of the symptoms listed, especially if you have a lump that grows rapidly.

Causes

It's not clear why most peripheral nerve tumors develop. Some are linked to known inherited syndromes, such as neurofibromatosis (types 1 and 2) and schwannomatosis. Others may be caused by a malfunctioning gene or triggered by injury or surgery.

Risk factors

Peripheral nerve tumors are more common in people who have:

  • Neurofibromatosis (types 1 and 2) and schwannomatosis. In these disorders, tumors develop on or near the nerves throughout the body. These tumors, which are frequently multiple, can lead to a variety of symptoms and signs depending on their location. These tumors are usually noncancerous.
  • A history of radiation treatment. If you were exposed to radiation, you are at increased risk of peripheral nerve tumors years later.

Complications

Both noncancerous and cancerous peripheral nerve tumors can compress nerves, leading to complications, some of which may be permanent:

  • Numbness and weakness in the affected area
  • Loss of function in the affected area
  • Difficulties with balance
  • Pain

Coping and support

Dealing with the possibility of permanent complications of peripheral nerve tumors and deciding which treatment would be best for you can be quite stressful. Here are some suggestions you may find helpful:

  • Educate yourself about peripheral nerve tumors. The more you know, the better prepared you'll be to make good choices about treatment. Besides talking to your doctor, you may want to talk to a counselor or a social worker. Or you may find it helpful to talk to other people who've had a condition like yours and 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 difficult time. Sometimes, though, you may find the concern and understanding of other people with a condition like yours especially comforting.

    Your doctor or a social worker may be able to put you in touch with a support group.

Preparing for an appointment

If your primary care doctor thinks you have a peripheral nerve tumor, he or she may refer you to a doctor who specializes in disorders of the nervous system (neurologist) or a doctor trained in brain and nervous system surgery (neurosurgeon).

What you can do

Before the appointment, you might want to prepare a list of answers to the following questions:

  • When did you first notice this problem?
  • Has it worsened with time?
  • Have your parents or siblings ever had similar symptoms?
  • Do you have other medical problems?
  • What medications or supplements do you take regularly?
  • What surgeries have you had?

What to expect from your doctor

Your doctor may ask some of the following questions:

  • Do you have pain? Where is it?
  • Do you have any weakness, numbness or tingling?
  • Have your symptoms been continuous or occasional?
  • What treatments have you tried already for these problems?

Overview

A schwannoma is a type of nerve tumor of the nerve sheath. It's the most common type of benign peripheral nerve tumor in adults. It can occur anywhere in your body, at any age.

A schwannoma typically comes from a single bundle (fascicle) within the main nerve and displaces the rest of the nerve. When a schwannoma grows larger, more fascicles are affected, making removal more difficult. In general, a schwannoma grows slowly.

If you develop a schwannoma in an arm or leg, you may notice a painless lump. Schwannomas are rarely cancerous, but they can lead to nerve damage and loss of muscle control. See your doctor if you have any unusual lumps or numbness.

Diagnosis

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

  • Magnetic resonance imaging (MRI). This scan uses a magnet and radio waves to produce a detailed, 3-D view of your nerves and surrounding tissue.
  • Computerized tomography (CT). A CT scanner rotates around your body to record a series of images. A computer uses the images to make a detailed view of your growth so that your doctor can evaluate how it may be affecting you.
  • Electromyogram (EMG). For this test, your doctor places small needles in your muscles so an electromyography instrument can record the electrical activity in your muscle as you try to move it.
  • Nerve conduction study. You're likely to have this test along with your EMG. It measures how quickly your nerves carry electrical signals to your muscles.
  • Tumor biopsy. If imaging tests identify a nerve tumor, your doctor may remove and analyze a small sample of cells (biopsy) from your tumor. Depending on the tumor's size and location, 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 take a nerve biopsy.

Treatment

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

  • Monitoring. Your doctor may suggest observing 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.
  • Surgery. An experienced peripheral nerve surgeon can remove the tumor if it is causing pain or growing quickly. Schwannoma surgery is done under general anesthesia. Depending on the location of the tumor, some patients can go home the day of surgery. Others may need to stay in the hospital for one or two days. Even after successful removal of the tumor during surgery, a tumor may recur.
  • Radiation therapy. Radiation therapy is used to help control the tumor growth and improve your symptoms. It may be used in combination with surgery.
  • Stereotactic radiosurgery. If the tumor is near 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 precisely to a tumor without making an incision.