Schwannomatosis is caused by a change in a gene, called a mutation, that helps control how cells grow. When these genes don't work as they should, tumors can form.

• SMARCB1- and LZTR1-related schwannomatosis. Changes in the SMARCB1 or LZTR1 genes can cause these tumors. These genes are both tumor suppressor genes. A tumor suppressor gene helps keep cells from growing or dividing too fast. Changes in these genes usually happen to someone for the first time in a family and are not inherited from a parent.
• Other types. These include 22q-related schwannomatosis, which is rare. They also include types where genetic testing doesn't show a clear cause. When results are missing or unclear, healthcare professionals may describe the condition as "schwannomatosis, not otherwise specified (NOS)" or "schwannomatosis, not elsewhere classified (NEC)."

There is currently no known way to prevent schwannomatosis. The gene changes that cause the condition can happen spontaneously or be inherited. They are not linked to lifestyle, diet or environmental factors.

If schwannomatosis runs in your family, genetic counseling and testing can help identify your risk and help you plan for early care. Regular checkups and imaging may detect tumors early, when treatment can be easier and help protect nerve function.

Complications of schwannomatosis depend on the type and where the tumors grow.

SMARCB1- and LZTR1-related schwannomatosis complications

Pain from these types can be severe and may limit daily activities. Tumors that press on nerves can cause numbness, weakness or loss of function in affected areas. Some people need surgery or care from a pain specialist to help manage symptoms. Pain can be severe and may limit daily activities. Living with long-term pain also can affect emotional well-being. Support or counseling may help.

Learning you have schwannomatosis may cause a range of emotions. Joining a support group that meets in person or online may help you cope with the emotions you're feeling. It also may help to reach out to family members and friends for support.

To diagnose schwannomatosis, a healthcare professional reviews your personal and family medical history and performs a physical exam.

You also may need other tests to confirm the diagnosis and determine which type you have. These types include NF2-related schwannomatosis (NF2), SMARCB1-related schwannomatosis and LZTR1-related schwannomatosis.

Other tests include:

• Eye exam. An eye exam can check for vision changes or cataracts, which are sometimes linked with nerve tumors.
• Hearing and balance exams. These include a test that measures hearing called audiometry and a test that measures balance by recording eye movements, known as electronystagmography. Another test measures the electrical messages that carry sound from the inner ear to the brain, known as brainstem auditory evoked response.
• Imaging tests. MRI is the main imaging tool for schwannomatosis. It can reveal tumors in the brain, spinal cord or peripheral nerves and detect very small growths. X-rays or CT scans can help identify bone changes, tumors in the brain or spinal cord, and very small tumors. Imaging tests also are used to monitor the condition after diagnosis.
• Genetic tests. Genetic tests look for changes in the SMARCB1, LZTR1 or NF2 genes. These tests can confirm the type of schwannomatosis, though sometimes no gene change is found. Genetic counseling can help families understand test results and inherited risk.

Schwannomatosis is a rare condition. It causes slow-growing tumors called schwannomas to form on the nerve sheath. A peripheral nerve sheath tumor starts in the covering on nerves outside the brain and spinal cord. When a tumor starts in Schwann cells, it's called a schwannoma. These tumors are usually benign, which means they are not cancerous. They can form on nerves in the brain and spine, and on peripheral nerves throughout the body. Schwannomatosis often starts in early adulthood.

Most people have a type of schwannomatosis that is linked to a gene change. Types are now named by the gene they are linked to:

• SMARCB1-related schwannomatosis.
• LZTR1-related schwannomatosis.
• NF2-related schwannomatosis.
• Some types are labeled schwannomatosis when a clear gene cause is not found yet.

Some people inherit a gene change that causes the tumor. But many gene changes happen for the first time in a family. In other words, they happen spontaneously and are not inherited. Not everyone who has a gene change develops symptoms. Genetic counseling and testing can help you and your family understand risk.

The most common symptom of schwannomatosis is pain. Other symptoms depend on which nerves are affected. Common symptoms include headaches, hearing changes and balance trouble. Symptoms vary from person to person.

Diagnosing schwannomatosis may involve an imaging test such as an MRI. It also may involve a biopsy of the tumor and genetic testing to identify the type of schwannomatosis.

Treatment for schwannomatosis aims to reduce pain and protect function. Some people only need observation for small tumors if they don't cause symptoms. Treatment options may include surgery and pain management with medicines or procedures. Care is often provided by a specialized team experienced in nerve tumor conditions.

You may be referred to a specialist in brain and nervous system conditions, known as a neurologist.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance, such as fasting before a specific test. Before your appointment:

• Write down a list of concerns, making a note of when you first noticed them.
• Bring a complete medical and family history with you.
• Write down key personal information, including any major stresses or recent life changes.
• Make a list of all medicines, vitamins or supplements that you are taking.
• Write down questions to ask your healthcare professional.

For schwannomatosis, basic questions to ask include:

• What type of schwannomatosis do I have?
• What tests do I need?
• What treatments are available?
• How should the condition be monitored for changes?

Don't hesitate to ask other questions.

What to expect from your doctor

Your healthcare professional is likely to ask you several questions, including:

• When did you first notice symptoms?
• Have your symptoms changed over time?
• Is there a family history of schwannomatosis?

Schwannomatosis symptoms depend on the type. Symptoms develop slowly over time and can vary widely from person to person.

SMARCB1- and LZTR1-related schwannomatosis

These two types of schwannomatosis typically affect people after age 20. Symptoms usually appear between ages 25 and 30.

They cause slow-growing nerve sheath tumors that can develop on nerves in the brain, spine and peripheral nerves throughout the body. Tumors also may affect cranial nerves that control vision or eye movement.

Common symptoms include:

• Long-lasting pain, which can occur anywhere in the body and may be disabling.
• Numbness, tingling or weakness in parts of the body.
• Muscle loss in areas where nerves are affected.
• Occasionally, balance problems or hearing changes, depending on tumor location.

SMARCB1- and LZTR1-related schwannomatosis rarely affect the hearing nerve. When they do, tumors usually occur in one ear only. This differs from NF2-related schwannomatosis, which often causes tumors in both ears and greater hearing loss.

When to see a doctor

See a healthcare professional if you have symptoms of schwannomatosis, such as ongoing pain, numbness, weakness, or new balance or hearing changes. Getting checked early can help find tumors when they are small and prevent nerve damage. There is no cure. But complications can be treated, and symptoms can often be managed.

Treatment for schwannomatosis focuses on managing pain, preserving nerve function and monitoring tumor growth. Care often involves a multidisciplinary team, including specialists in neurology, neurosurgery, pain medicine and genetics. There is no cure, but many treatments can improve comfort and quality of life.

Surgery and other procedures

Surgery or other procedures may be needed to treat serious symptoms or complications.

• Surgery to remove tumors. Surgery may be recommended to remove tumors that cause pain or affect vital functions such as hearing or balance. While surgery can help ease symptoms, it does not cure schwannomatosis.
• Stereotactic radiosurgery. This procedure delivers radiation to the tumor without the need to cut into the body. Stereotactic radiosurgery might be an option to control tumor growth linked to NF2-related schwannomatosis while helping to preserve hearing.

Cancer treatment

Tumors linked to schwannomatosis rarely turn into cancer. If they do, they're treated with standard cancer therapies, such as surgery, chemotherapy and radiation therapy. Early diagnosis and treatment are the most important factors for a good outcome.

Pain medicines

Managing pain is an important part of treatment for SMARCB1- and LZTR1-related schwannomatosis. Your healthcare professional might recommend:

• Medicines for nerve pain such as gabapentin (Neurontin, Gralise) or pregabalin (Lyrica).
• Tricyclic antidepressants such as amitriptyline.
• Serotonin and norepinephrine reuptake inhibitors such as duloxetine (Cymbalta).
• Epilepsy medicines such as topiramate (Topamax, Qudexy XR, others) or carbamazepine (Carbatrol, Tegretol, others).

Researchers are studying medicines that can shrink noncancerous tumors that grow on the hearing and balance nerves in the ears.

Monitoring and long-term care

Regular MRI scans and exams help monitor tumor growth and nerve function. Some people join clinical trials studying new medicines that may slow tumor growth or relieve pain. Support groups, counseling and integrative therapies also can help manage chronic pain and improve well-being.