Schwannomatosis

Overview

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.

Symptoms

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.

Causes

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)."

Risk factors

A risk factor is something that increases the chance of developing a condition.

Schwannomatosis happens because of a change, called a mutation, in certain genes. The gene that causes schwannomatosis is sometimes passed down from a parent. The risk of inheriting the gene differs based on the type of schwannomatosis.

In SMARCB1- and LZTR1-related schwannomatosis, the disease is less likely to be passed down from a parent. Most cases happen by chance, with no family history.

Having a parent with schwannomatosis slightly increases your risk. Researchers estimate that the risk of inheriting the SMARCB1- and LZTR1-related schwannomatosis gene change from an affected parent is about 15%.

There are no known lifestyle, diet or environmental factors that cause schwannomatosis. If you have a family history of schwannomatosis, genetic counseling and testing can help you understand your genetic risk and your family's options for monitoring.

Complications

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.

Prevention

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.