Composite ganglioside autoantibodies and immune treatment response in MMN and MADSAM

ABSTRACT Introduction : Multifocal motor neuropathy (MMN) is a motor only, asymmetric onset neuropathy that is relatively treatment‐refractory compared with classic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy. Methods : We reviewed 35 patients seropositive for GM1 (monosialo‐asialo [immunoglobulin M, IgM; immunoglobulin G, IgG]) and/or GD1b (disialo [IgG, IgM]) autoantibodies having MMN, classic CIDP, or MADSAM. Immune‐treatment responsiveness and clinical course was compared with antibody negative disease controls. Results : Seventy‐nine percent of seropositives with an initial diagnosis of MMN were immunotherapy responsive compared with 46% of seronegatives ( P = 0.045). Eight ganglioside antibody positive MMN patients of 19 (42%) developed sensory findings consistent with MADSAM compared with 3 of 41 (7%) seronegative MMN patients ( P = 0.003). MMN and MADSAM patients with ganglioside antibody positivity had more sustained treatment responses ( P = 0.03). Discussion : Patients initially diagnosed with MMN seropositive for diverse GM1 autoantibodies appear more likely to have sustained treatment response and evolution to MADSAM. Muscle Nerve 57 : 1000–1005, 2018