Peripheral nerve tumors are growths in or near the strands of tissue (nerves) that transmit signals from your brain to the rest of your body. These nerves control your muscles so that you can walk, blink, swallow, pick things up and do other activities.

Peripheral nerve tumors can occur anywhere in the body. Most of them aren't cancerous (malignant), but they can lead to pain, nerve damage and loss of function in the affected area.

Treatment of peripheral nerve tumors usually involves surgery to remove the tumor. Sometimes the tumor can't be removed without damaging nearby healthy tissue and nerves. In these cases, other treatments may be recommended.

Several types of peripheral nerve tumors occur. These tumors affect nerves by growing within them (intraneural tumors) or by pressing against them (extraneural tumors).

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.

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.

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.

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

To diagnosis a peripheral nerve tumor, your doctor may ask you about signs and symptoms, discuss your medical history, and perform both a general physical and neurological exam. He or she may order several tests to help pinpoint the cause of your signs and symptoms.

• 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 peripheral nerve tumor 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. Sometimes this is the only way to determine whether a tumor is cancerous.
• 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.

Peripheral nerve tumors are uncommon. Ask your doctor if he or she is experienced in diagnosing and treating them. If needed, seek a second opinion.

Your peripheral nerve tumor treatment depends on the type of tumor you have, what nerves and other tissues it affects, and your symptoms. Treatment options for peripheral nerve tumors include:

Monitoring

Waiting and watching to see if the tumor grows may be an option if it's in a place that makes removal difficult or if the tumor is small, slow growing, and causes few or no signs and symptoms. You'll have regular checkups and may undergo CT or MRI scans every few months to see if your tumor is growing.

Surgery

You may need surgery to remove a peripheral nerve tumor. The goal of surgery is to remove the entire tumor without damaging nearby healthy tissue and nerves. When that isn't possible, surgeons remove as much of the tumor as they can.

New techniques and instruments allow neurosurgeons to reach tumors that were once considered inaccessible. The high-powered microscopes used in microsurgery make it easier to distinguish a tumor from healthy tissue. Doctors also can monitor the function of nerves during surgery, which helps preserve healthy tissue.

Depending on the location and size of your peripheral nerve tumor, surgery can cause nerve damage and disability. These risks are often based on the size and location of the tumor and the surgical approach used. Some tumors grow back.

Stereotactic radiosurgery

Your doctor may recommend stereotactic radiosurgery to treat some peripheral nerve tumors in or around the brain. In stereotactic radiosurgery, such as Gamma Knife radiosurgery, doctors deliver radiation precisely to a tumor without making an incision.

Risks of radiosurgery include weakness or numbness in the treated area and treatment failure (continued tumor growth). Very rarely, the radiation could cause a cancer in the treated area in the future.

Cancer treatment

Malignant tumors are treated with standard cancer therapies, such as surgery, chemotherapy and radiation therapy. Early diagnosis and treatment are the most important factors resulting in good outcome. Tumors may recur after treatment.

Rehabilitation

After surgery, you may need physical rehabilitation. Your doctor may use a brace or a splint to keep your arm or leg in a position that helps you to heal. Physical therapists and occupational therapists can help you recover function and mobility lost due to nerve damage or limb amputation.

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.

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?