Multifocal motor neuropathy (MMN), also called multifocal motor neuropathy with conduction block (MMNCB), is a rare, acquired, motor neuropathy characterized by progressive asymmetric weakness without sensory problems. The syndrome has a fairly recent nosographic location, as it was described in 1986. It typically involves upper limbs more than the lower limbs. Electrodiagnostic studies often reveal an asymmetric motor neuropathy with characteristic conduction block. Serum IgM anti-ganglioside antibodies (anti-GM1) are present in the majority of the patients.
The syndrome is not included among neuropathies with severe clinical commitment and poor prognosis. In some cases, the symptoms are so mild that patients do not require any treatment. However, most patients may develop a progressive worsening of strength, especially in the hands and arms, which can induce difficulties to perform even simple daily tasks such as writing, washing, or dressing. However, these patients may benefit from drug treatments as they often have a favorable response to intravenous immunoglobulin (IVIG).
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