In an autoimmune disorder the body attacks its own healthy cells. Opsoclonus-myoclonus syndrome results from an autoimmune disorder in which the body's antibodies are responding to either a viral infection or a tumor called a neuroblastoma. In either case, the antibodies end up attacking the brain cells as well, and this causes the damage that produces the symptoms.
Opsoclonus-myoclonus syndrome occurs most often in children. Toddlers are the age group in which neuroblastoma most often develops; about four percent of these children will develop OMS. Any child who has OMS will be tested to see if she or he has a tumor, even if sick with a viral infection, since the two so often go together.
If the child has a tumor, the tumor is surgically removed. Sometimes this improves the OMS symptoms. In adults, tumor removal often does not help and the symptoms may even get worse. Early recognition and treatment is best.
Other treatments are:
- Adrenocorticotrophic hormone (ACTH) injections
- Intravenous immunoglobulins - commercial preparations of antibodies from healthy blood donors
- Azathioprine (Imuran) - suppresses the immune system, which slows the production of antibodies
- Oral and intravenous steroids, such as prednisone, dexamethasone, and hydrocortisone
- Chemotherapy such as cyclophosphamide and methotrexate, for children with neuroblastoma
- Therapeutic apheresis - exchanging blood plasma
- Immunoadsorption - cleaning the antibodies out of the blood has been tried in adults with OMS.
OMS may have long-lasting effects
People with the greatest chance of returning to normal after treatment are those who have the mildest symptoms. Those with more severe symptoms may have relief of their muscle twitching (myoclonus) but have difficulty with coordination. Other problems that come from brain injury, such as learning and behavior problems, attention-deficit hyperactivity disorder (ADHD), and obsessive-compulsive disorder, may occur, and these may need their own treatments. Children with the most severe OMS symptoms may have permanent brain damage that may cause physical and mental disabilities.
Many questions remain about opsoclonus-myoclonus syndrome. One is that no one yet knows how long children with OMS need to be treated. Are the immune problems present only at the beginning of the syndrome, or do they exist for years after? Another question concerns the brain injury that OMS causes: at what point does the damage become irreversible? Medical research to answer these and other questions about opsoclonus-myoclonus syndrome is needed.
Information for this article was taken from:
- National Institute of Neurological Disorders and Stroke. Opsoclonus Myoclonus Information Page
- Pranzatelli, M. "Opsoclonus-Myoclonus Syndrome." 4-page booklet available from South Illinois University School of Medicine.
- Pranzatelli, M. "Vital Signs: Friendly Fire." Discover, Vol. 32, No. 4 (April 2000).