Monofocal motor neuropathy: Improvement with intravenous immunoglobulin

Multifocal motor neuropathy (MMN) is a chronic, immune-mediate, peripheral myelinopathy. Inherent in its name, MMN implies involvement of two or more motor nerves. We report three patients with weakness and partial motor conduction block restricted to a single nerve and localized to sites that are not at risk for entrapment or compression injury. None of the patients had sensory involvement and all showed a favorable response to intravenous immunoglobulin therapy. Based on these observations and reports of three additional patients, we believe that monofocal motor neuropathy is a partial form of MMN and should be treated as such.