This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Multifocal motor neuropathy (MMN) causes damage to the nerves in the arms and legs. Nerve damage begins in adulthood and slowly gets worse over time. One side of the body may be more affected than the other. Symptoms of MMN may include weakness in the hands and lower arms; cramping; involuntary contractions or twitching; wrist drop or foot drop, and wasting of the affected muscles. MMN is thought to be due to an abnormal immune response, but the underlying cause is not clear. Diagnosis is based on the symptoms, clinical exam, and specific laboratory testing. Guidelines for diagnosis have been published. Treatment includes intravenous immune globulin (IVIG). Most people with MMN have rapid improvement in weakness with IVIG, but this treatment needs to be repeated regularly. Cyclophosphamide has also been effective in treating MMN. Physical and occupational therapy may be helpful for some people with MMN.
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