Nerve sheath tumors grow on the myelin and connective tissue that surrounds the nerve fibers. These tumors are rare, and the cause is often unknown. They can occur anywhere in the body including on nerves in the brain, the spine, and the peripheral nerves that connect the spinal cord to the body. Most nerve sheath tumors are noncancerous (benign) and grow slowly. Only between 5-10 percent of nerve sheath tumors are malignant.
Most Common Types of Nerve Sheath Tumors
The most common types of nerve sheath tumors are schwannomas and neurofibromas. Some people with nerve sheath tumors have no pain or other symptoms. Other people can experience pain, muscle weakness, numbness, and tingling if the tumor presses on a nerve.
These are the most common type of nerve sheath tumor. Schwannomas are composed of Schwann cells, a type of glial cell that helps form the myelin sheath that insulates nerve fibers. As Schwannoma tumors grow, they put pressure on the nerves. Schwannomas that grow on a nerve root coming out of the spine can cause painful symptoms similar to a herniated disc.
These tumors are generally part of an inherited condition called neurofibromatosis. They may also be from a genetic mutation. The tumors can come from Schwann cells or other cells that are part of the peripheral nervous system. Neurofibromas become particularly noticeable during adolescence. The person may have a number of small tumors affecting different parts of the body. If a tumor presses against a nerve, there may be pain or numbness in the area affected by that nerve. Other neurofibromas may not cause any symptoms.
Diagnosing Nerve Sheath Tumors
The physician will conduct a detailed neurological exam and ask about any family history of nerve sheath tumors. Imagining tests , such as an MRI or a CT scan, are helpful for diagnosis. A biopsy to remove a tissue sample may be performed to determine whether the tumor is cancerous.
Treatment of nerve sheath tumors depends on whether they are interfering with the nerve or spinal cord. If the tumor is small and produces few symptoms, the physician may just monitor it. Additional imaging scans may be performed every 6 to 12 months to determine if the tumor is growing.
When a tumor is restricting movement or causing pain, surgery to remove it may be an option. This depends on the size and location of the tumor. After surgical removal, nerve sheath tumors rarely come back. If a nerve sheath tumor is malignant, cancer treatments including radiation and chemotherapy may be used.