A schwannoma, also known as a neurinoma or neurilemmoma, is a benign tumor that arises from Schwann cells in the peripheral nervous system. These cells provide support and insulation for nerves.
Most schwannomas do not cause symptoms. Symptoms depend on where the tumor is located and can happen when the tumor presses on a nerve.
Depending on which nerve is affected, symptoms may include changes in hearing, vertigo, pain when speaking, digestive problems, or pain and tingling in an arm or leg. Treatment is typically recommended only when symptoms occur.
Main symptoms
In most cases, schwannomas do not cause noticeable signs or symptoms. According to the National Cancer Institute (NCI), when the tumor compresses a nerve, symptoms can develop based on the nerve or area involved:
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Compression of the auditory (acoustic) nerve: gradual hearing loss in one ear, dizziness, vertigo, loss of balance, ear pain;
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Compression of the trigeminal nerve: severe pain when speaking, eating, or drinking, facial numbness or facial paralysis;
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In the spinal canal: muscle weakness, digestive problems, and difficulty controlling the sphincters;
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In the limbs: pain, weakness, and tingling.
If you have symptoms that could suggest a schwannoma, it is important to see a neurologist or a primary care provider for evaluation. Tests that may be ordered include an MRI, CT scan, electromyogram, and/or biopsy.
Possible causes
The exact cause of schwannomas remains unknown. However, they are believed to be linked to genetic factors.
This type of tumor is more common in people with neurofibromatosis, an inherited condition linked to abnormal growth of nerve tissue. This can lead to the formation of small nodules and tumors.
Treatment options
In most cases, a schwannoma does not require treatment, especially when there are no symptoms, because it is a benign tumor. According to the NCI, a doctor may recommend monitoring over time, sometimes using a “watch and wait” approach.
If the tumor is compressing a nerve and causing symptoms, surgery to remove it may be recommended. A biopsy is typically performed afterward.
If the biopsy shows features suggestive of malignancy, which is rare, radiation therapy afterward may be recommended. Radiation therapy may also be considered when the tumor is in a hard-to-reach area or when surgery carries higher risk.
For large schwannomas, a doctor may recommend chemotherapy before surgery to reduce the tumor size and make removal possible. In cases where surgery cannot be done, chemotherapy and/or radiation therapy sessions may be recommended.