Multifocal motor neuropathy (MMN) is a rare, immune-mediated condition that primarily affects the peripheral nerves, causing progressive and asymmetric muscle weakness without significant sensory loss. Diagnosing MMN can be challenging due to its overlap with more common disorders like amyotrophic lateral sclerosis (ALS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Misdiagnosis is common and can delay appropriate treatment, leading to irreversible neurological damage. Electrophysiological studies revealing conduction block, particularly in non-compressive sites, are crucial for accurate diagnosis. Additionally, the presence of anti-GM1 antibodies can support the diagnosis of MMN, though their absence does not rule it out.

Treatment for MMN typically involves intravenous immunoglobulin (IVIG), which has been shown to improve muscle strength and reduce disability. Subcutaneous immunoglobulin (SCIG) is also an effective alternative for maintenance therapy. Unlike other neuropathies, MMN does not respond well to corticosteroids or plasma exchange, which can actually worsen symptoms. Early and accurate diagnosis, coupled with appropriate therapy, is essential for preventing long-term disability and improving the quality of life for patients with MMN.

Reference: Allen JA, Clarke AE, Harbo T. A Practical Guide to Identify Patients With Multifocal Motor Neuropathy, a Treatable Immune-Mediated Neuropathy. Mayo Clin Proc Innov Qual Outcomes. 2024 Jan 8;8(1):74-81. doi: 10.1016/j.mayocpiqo.2023.12.002. PMID: 38283096; PMCID: PMC10819864.