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Diseases

Genetic and Rare Diseases Information Center (GARD)

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Multifocal motor neuropathy


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Overview



What is multifocal motor neuropathy?

What are the signs and symptoms of multifocal motor neuropathy?

What causes multifocal motor neuropathy?

How might multifocal motor neuropathy be treated?


What is multifocal motor neuropathy?

Multifocal motor neuropathy is a progressive muscle disorder that primarily affects the upper limbs, however the lower limbs can also be affected. Signs and symptoms include weakness in the hands and lower arms, and less often (and typically less severe) weakness in the lower limbs. People with this neuropathy may experience cramping, involuntary contractions or twitching, and wasting of affected muscles. It is typical for there to be differences from one side of the body to the other in the specific muscles involved.[1] Multifocal motor neuropathy is caused by abnormal activity of the body's immune system. While there is currently no cure for multifocal motor neuropathy, symptoms tend to be greatly improved with regular/periodic immunoglobulin therapy.[2]
Last updated: 5/1/2013

What are the signs and symptoms of multifocal motor neuropathy?

Signs and symptoms of multifocal motor neuropathy may include weakness, cramping, involuntary contractions or twitching, and wasting of affected muscles.[1] Muscles in the hands and lower arms are most commonly and severely affected, however muscles in the lower limbs may also be involved. It is typical for muscles of the left and right sides to be differently involved/affected.[2][1]
Last updated: 5/1/2013

What causes multifocal motor neuropathy?

Multifocal motor neuropathy is caused by abnormal activity of the body's immune system.[2] Most people with this neuropathy have detectable autoantibodies. Autoantibodies are antibodies that mistakenly target and damage specific tissues or organs of the body.[3] One or more autoantibodies may be produced by a person's immune system when it fails to distinguish between "self" and "non-self" proteins.[3] The most common autoantibody detected in people with multifocal motor neuropathy is anti-GM1 IgM.[2]
Last updated: 5/1/2013

How might multifocal motor neuropathy be treated?

Treatment for multifocal motor neuropathy varies. Some individuals experience only mild, modest symptoms and require no treatment.[1] For others, treatment generally consists of intravenous immunoglobulin (IVIg) or immunosuppressive therapy with cyclophosphamide.[1] Improvement in muscle strength usually begins within 3 to 6 weeks after treatment is started. Most patients who receive treatment early experience little, if any, disability. However, there is evidence of slow progression over many years.[1]
Last updated: 5/1/2013

References
  1. NINDS Multifocal Motor Neuropathy Information Page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/multifocal_neuropathy/multifocal_neuropathy.htm. Accessed 5/1/2013.
  2. Guimarães-Costa R, Bombelli F, Léger JM. Multifocal motor neuropathy. Presse Med. 2013 Apr 24; http://www.ncbi.nlm.nih.gov/pubmed/?term=23623583. Accessed 5/1/2013.
  3. American Association for Clinical Chemistry. Autoantibodies. LabTestsOnline. January 12, 2012; http://labtestsonline.org/understanding/analytes/autoantibodies/. Accessed 5/1/2013.