Schwannomatosis

July, 19th, 2024

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Schwannomatosis is a condition that results in slow-growing tumors on nerve tissue. The tumors can grow on nerves in the ears, brain, spine and eyes. They also can grow on peripheral nerves, which are nerves located outside of the brain and spinal cord. Schwannomatosis is rare. It’s usually diagnosed in early adulthood.

There are three types of schwannomatosis. Each type is caused by an altered gene.

In NF2-related schwannomatosis (NF2), tumors grow in both ears and can cause hearing loss. The altered gene that causes this type is sometimes passed down from a parent. NF2-related schwannomatosis was previously known as neurofibromatosis 2 (NF2).

The other two types of schwannomatosis are SMARCB1-related schwannomatosis and LZTR1-related schwannomatosis. The altered genes that cause these types usually are not passed down through families.

The tumors caused by schwannomatosis usually are not cancerous. Symptoms can include headaches, hearing loss, trouble with balance and pain. Treatment focuses on managing symptoms.

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Symptoms

Schwannomatosis symptoms depend on the type.

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NF2-related schwannomatosis

Symptoms of NF2-related schwannomatosis (NF2) usually result from slow-growing tumors in both ears, known as acoustic neuromas or vestibular schwannomas. The tumors are benign, which means that they are not cancerous.

The tumors grow on the nerve that carries sound and balance information from the inner ear to the brain. These tumors can cause hearing loss.

Symptoms tend to appear during the late teen and early adult years, and can vary. Symptoms may include:

• Gradual hearing loss.
• Ringing in the ears.
• Poor balance.
• Headaches.

Sometimes NF2 can lead to the growth of tumors on other nerves, including in the brain, spine and eyes. They also can grow on peripheral nerves, which are located outside of the brain and spinal cord. People who have NF2 also may develop other benign tumors.

Symptoms of these tumors can include:

• Numbness and weakness in the arms or legs.
• Pain.
• Poor balance.
• Facial drop.
• Changes in vision or cataracts.
• Seizures.
• Headaches.

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SMARCB1- and LZTR1-related schwannomatosis

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

SMARCB1- and LZTR1-related schwannomatosis can cause tumors to grow on nerves in the brain, spine and eyes. Tumors also may grow on peripheral nerves located outside of the brain and spinal cord.

Symptoms of SMARCB1- and LZTR1-related schwannomatosis include:

• Long-lasting pain, which can occur anywhere in the body and can be disabling.
• Numbness or weakness in various parts of the body.
• Loss of muscle, known as atrophy.

These types of schwannomatosis also can cause tumors to grow in the ear. But it happens rarely, and tumors usually grow in only one ear. This differs from NF2, which causes tumors to grow in both ears. For this reason, people with SMARCB1- and LZTR1-related schwannomatosis don’t have the same hearing loss as people who have NF2.

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When to see a doctor

See a healthcare professional if you have symptoms of schwannomatosis. Although there is no cure, complications can be treated.

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Causes

Schwannomatosis is caused by an altered gene. The specific genes involved depend on the type:

• NF2-related schwannomatosis (NF2). The NF2 gene produces a protein called merlin, also called schwannomin, that suppresses tumors. An altered gene causes a loss of merlin, leading to cell growth that’s not controlled.
• SMARCB1- and LZTR1-related schwannomatosis. So far, two genes are known to cause these types of schwannomatosis. Changes of the genes SMARCB1 and LZTR1, which suppress tumors, are linked with these conditions.

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Risk factors

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.

For about half of people who have NF2-related schwannomatosis (NF2), they received an altered gene from a parent that caused the disease. NF2 has an autosomal dominant inheritance pattern. This means that any child of a parent who is affected by the disease has a 50% chance of having the gene change. People who have NF2 and whose relatives aren’t affected are likely to have a new gene change.

In SMARCB1- and LZTR1-related schwannomatosis, the disease is less likely to be passed down from a parent. Researchers estimate that the risk of inheriting SMARCB1- and LZTR1-related schwannomatosis from an affected parent is about 15%.

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In an autosomal dominant disorder, the changed gene is a dominant gene. It’s located on one of the nonsex chromosomes, called autosomes. Only one changed gene is needed for someone to be affected by this type of condition. A person with an autosomal dominant condition — in this example, the father — has a 50% chance of having an affected child with one changed gene and a 50% chance of having an unaffected child.

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Autosomal dominant inheritance pattern Complications

Complications can occur in schwannomatosis, and they depend on the type the person has.

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NF2-related schwannomatosis complications

NF2-related schwannomatosis (NF2) complications can include:

• Partial or total hearing loss.
• Facial nerve damage.
• Vision changes.
• Small benign skin tumors, known as skin schwannomas.
• Weakness or numbness in the legs or arms.
• Having many benign brain tumors or spinal tumors, known as meningiomas. These require frequent surgeries.

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SMARCB1- and LZTR1-related schwannomatosis complications

The pain caused by this type of schwannomatosis can be weakening. People with this type may need surgery or management by a pain specialist.

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Diagnosis

To diagnose schwannomatosis, a healthcare professional begins with a review of your personal and family medical history and a physical exam. You also may need other tests to diagnose NF2-related schwannomatosis (NF2) or SMARCB1- and LZTR1-related schwannomatosis.

Other tests include:

• Eye exam. An eye exam can reveal cataracts and visual loss.
• 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 brain stem auditory evoked response.
• Imaging tests. X-rays, CT scans or MRIs 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 won’t always identify NF2 or SMARCB1- and LZTR1-related schwannomatosis because other genes that aren’t known may be involved with the condition. However, some people choose genetic testing before having children.

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Treatment

Treatment for schwannomatosis may include surgery or pain management. You may need regular exams and tests to monitor tumor growth. There is no cure for schwannomatosis.

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Surgery and other procedures

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

• Surgery to remove tumors. People who have NF2-related schwannomatosis (NF2) and have hearing loss, brain stem compression or tumor growth, may need surgery to remove acoustic neuromas. Complete removal of the tumors can ease pain.
• Stereotactic radiosurgery. This procedure delivers radiation to the tumor without the need to cut into the body. Stereotactic radiosurgery might be an option to remove acoustic neuromas related to NF2 while preserving hearing.
• Auditory brain stem implants and cochlear implants. These devices might help improve your hearing if you have NF2 and hearing loss.

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Cancer treatment

If tumors become cancerous, 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.

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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, Horizant) 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.

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Coping and support

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. Also reach out to family members and friends for support.

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Preparing for an appointment

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

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

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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.

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What to expect from your doctor

Your healthcare provider 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?