Multifocal motor neuropathy (MMN) is a rare, treatable neuropathy, but good long-term outcomes are dependent on early treatment. Appropriate diagnostic criteria exist for MMN, but it has a heterogeneous clinical presentation, and, when confined to a small group of nerves, its clinical presentation can overlap with entrapment neuropathies. Electrodiagnosis is a useful diagnostic technique but occasionally MMN can be misdiagnosed as entrapment neuropathies. Misdiagnosis should rarely occur since the nerve involvement in MMN is usually not at sites of common nerve entrapment, and the impact of misdiagnosis can be substantial. The treatments of these conditions differ significantly: intravenous immunoglobulin is the standard therapy for MMN, while treatment options for entrapment neuropathies include conservative treatment, such as splinting, corticosteroids, or surgery. Such treatment in MMN may worsen symptoms, potentially leading to progressive motor symptoms, including muscle weakness, atrophy, and significant motor disability. Two exemplary cases are presented, which highlight the importance of differential diagnosis of these conditions. Emerging technologies, such as high-resolution sonography and magnetic resonance neurography, will aid in defining future diagnostic criteria of MMN.
Intravenous Immunoglobulin Treatment in Multifocal Motor Neuropathy
