Schwannomatosis is a disease that causes schwannomas (nerve tumors). Schwannomas grow on the insulating sheaths around peripheral nerves. These tumors can grow on nerves throughout the body, including on spinal nerve roots. At the Spine Hospital at the Neurological Institute of New York, we specialize in treating spinal schwannomas.
Schwannomas are almost always benign tumors. That is, they are not cancerous and will not spread. But even benign schwannomas can cause undesirable symptoms when they put pressure on nearby structures.
Schwannomatosis is part of a family of diseases called neurofibromatoses. There are three forms of neurofibromatosis: Neurofibromatosis Type 1 (NF1), Neurofibromatosis Type 2 (NF2), and schwannomatosis. Read about the other two forms on the neurofibromatosis page here.
The characteristic symptom of schwannomatosis is the growth of nerve tumors called schwannomas throughout the body.
Symptoms of schwannomatosis are very similar to those of the related tumor disease NF2. However, NF2 commonly involves the eighth cranial nerve, which controls balance and hearing, whereas schwannomatosis does not.
The distinction between schwannomatosis and NF2 is not minor: the diseases are managed differently and carry different outlooks. For instance, schwannomatosis is associated with an average life expectancy, while NF2 is associated with a shorter-than-average life expectancy.
Schwannomatosis can reduce quality of life for some patients, however. Without treatment, the nerve tumors associated with this disease can cause nerve pain and other symptoms.
As spinal schwannomas grow and put pressure on the spinal nerves, they can cause symptoms including changes in sensation (pain, numbness, pins and needles), changes in movement (clumsiness, trouble walking), or trouble controlling bladder and bowel function. Exact symptoms vary depending on the tumor’s size and location, and the degree of pain can vary from mild to extreme. Most spinal tumors can be fully removed.
Causes and Risk Factors
The causes of schwannomatosis are not fully understood.
Schwannomatosis sometimes results from a change in a gene called SMARCB1. It is possible for this change to be inherited, or passed along to offspring, but it is not always.
In other cases, schwannomatosis develops for reasons that are not yet known, without a change in SMARCB1.
Tests and Diagnosis
The diagnosis of schwannomatosis includes several forms of testing. MR (magnetic resonance) and CT (computed tomography) scans may be performed to look for growths on nerve tissue. MR scans use magnets, radio waves, and computer technology to produce images of organs and tissues like the brain and spinal cord. CT scans use a combination of X-rays and computer technology to produce detailed images of bones and soft tissues.
Pathologists may examine tissue from biopsied or removed tumors to determine the tumor type.
Genetic testing may be conducted to look for changes associated with schwannomatosis or NF2.
A doctor experienced with schwannomatosis can evaluate the results of the imaging scans, genetic tests, the family history, and the laboratory examination of tumor tissue.
The treatment of spinal schwannomas depends on the size, location, and symptoms of the tumor. Small tumors producing no pressure on nearby tissues can often be observed over time with yearly MR.
For larger or symptomatic tumors, or tumors showing growth over time, surgical removal is usually recommended. In most patients, complete removal of these tumors can be safely achieved using a surgical microscope, very fine instruments, and an array of microsurgical techniques. In many cases, patients experience an improvement in neurological function.
In some patients with large dumbbell tumors, spinal stabilization and fusion may be performed following complete tumor removal (see video).