Multifocal Motor Neuropathy: Is Conduction Block Essential to the Diagnosis?

Multifocal motor neuropathy (MMN) is an immune-mediated demyelinating neuropathy characterized clinically by asymmetric weakness and atrophy, typically in the distribution of individual peripheral nerves. It is important to distinguish MMN from amyotrophic lateral sclerosis (ALS) and other degenerative lower motor neuron syndromes because MMN can respond to intravenous immunoglobulin (IVIg) or other forms of immunotherapy. The characteristic electrophysiologic hallmark of MMN is persistent conduction block (CB) in motor nerves in regions not usually associated with compression or entrapment.

These researchers retrospectively assessed clinical features, electrophysiologic features, and response to IVIg treatment in patients with MMN with CB (…