Motor neuropathies and multifocal motor neuropathy with conduction block are treatable causes of neuropathy that present with the clinical syndrome of asymmetric motor weakness with atrophy, which may mimic amyotrophic lateral sclerosis. The diagnosis of the disorder relies on the typical clinical presentation as well as electrodiagnostic findings of conduction block at noncompression sites and often on anti-GM1 IgM antibodies on serum testing. The mainstay of therapy includes intravenous immunoglobulin, but often other immunomodulating therapy is required for long-term management. In this clinical summary, Drs. Traub and Brannagan of Columbia University have reviewed the most recent literature covering pathophysiology, diagnostic criteria, and treatment for motor neuropathy.