Nerve Sheath Tumor: What You Need to Know
Nerve sheath tumors include schwannomas, neurofibromas and others. They grow slowly but may eventually press against the spinal cord or nerve and cause pain or loss of function.
Genetic conditions called neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2) and schwannomatosis are characterized by multiple nerve sheath tumors.
A single (or sporadic) nerve sheath tumor can also occur in people who do not have NF1, NF2 or schwannomatosis.
About 5 percent of all peripheral nerve sheath tumors are malignant.
What is a nerve sheath tumor?
The nerve sheath is a layer of myelin and connective tissue that surrounds and insulates nerve fibers. A nerve sheath tumor is a growth within the cells of this covering.
Nerve Sheath Tumor Symptoms
Some people with nerve sheath tumors do not experience symptoms, but others may notice:
Numbness, tingling, itching or a burning sensation
A mass that the person can see or feel
Nerve Sheath Tumor Diagnosis
In most cases, MRI can evaluate and diagnose nerve sheath tumors. In some cases, such as when there are concerns that the tumor may be malignant, the doctor may recommend a biopsy in order to make a diagnosis.
A nerve sheath tumor may appear on imaging such as an MRI or ultrasound when a person is being evaluated for one of the symptoms listed above. Or the tumor can be an incidental finding — discovered when a doctor is using MRI to examine a person for something else, such as lower back pain.
What causes nerve sheath tumors?
Most cases of nerve sheath tumors are sporadic, and their cause is unknown. In other instances, they are part of a genetic condition such as NF1, NF2 or schwannomatosis, which are characterized by multiple nerve sheath tumors.
Nerve Sheath Tumor Treatment
Nerve sheath tumors are relatively rare; therefore, it is important for patients to consult with an expert who routinely treats people with this diagnosis and who is familiar with the potential risks and benefits of treatment options.
Most benign nerve sheath tumors need no treatment other than observation, which involves following up with repeat physical examinations and serial imaging.
Some nerve sheath tumors are treated with surgery. Addressing malignant peripheral nerve sheath tumors may involve multiple approaches including radiation, chemotherapy and surgery. If a person needs surgery for nerve sheath tumors, it is important to entrust expert surgeons since there is a risk of nerve damage with surgical treatment.
While surgery is taking place, the surgeon may monitor nerve function using evoked potentials or electromyography to optimize safety and provide the best chance for a good result.