Multifocal Motor Neuropathy (MMN)

Multifocal motor neuropathy (MMN) is an immune-mediated neuropathy affecting motor fibers, usually in the distribution of individual nerves. It presents with chronic asymmetric distal limb weakness, atrophy, and fasciculations; affecting the distal arm more frequently than the leg, with limited or no sensory symptoms. Electrophysiological studies give clues to the diagnosis and documentation of motor conduction blocks. IgM anti-GM1 antibodies are seen in half of the patients. The condition responds well to IVIg. In refractory cases, immunomodulatory therapy like rituximab and cyclophosphamide can be given.