Multifocal motor neuropathy: a review of pathogenesis, diagnosis, and treatment

Abstract

Multifocal motor neuropathy (MMN) is an uncommon, purely motor neuropathy associated with asymmetric deficits with predilection for upper limb involvement. Even in the early descriptions of MMN, the associations of anti-GM1 antibodies and robust response to immunomodulatory treatment were recognized. These features highlight the likelihood of an underlying autoimmune etiology of MMN. The clinical presentation of MMN can closely mimic several neurological conditions including those with more malignant prognoses such as motor neuron disease. Therefore early and rapid recognition of MMN is critical. Serological evidence of anti GM-1 antibodies and electrodiagnostic findings of conduction block are helpful diagnostic clues for MMN. Importantly, these diagnostic features are not universally present, and patients lacking these characteristic findings can demonstrate similar robust response to immunodulatory treatment. In the current review, recent research in the areas of diagnosis, pathogenesis, and treatment of MMN and needs for the future are discussed. The characteristic findings of MMN and treatment implications are reviewed and contrasted with other mimicking disorders.

Respiratory management of patients with neuromuscular disease: current perspectives

“…Multifocal motor neuropathy is an autoimmune motor neuropathy preferentially involving the distal upper limbs. 42 There exists a single case report of presentation with respiratory failure. 43 In the appropriate clinical context, this diagnosis should be considered, given its response to therapy with intravenous immunoglobulins.…”

Applying complement therapeutics to rare diseases

“…Although the pathophysiological mechanisms are not fully understood, the disease is often associated with serum IgM antibodies against the ganglioside GM1. MNN does not respond well to corticosteroids and, plasmapheresis and IVIg, though the first-line therapy offer only transient results, often requiring repeated infusions [112, 113]. …”

Severe Periodontal Disease Associated with Long-Term Treatment with Intravenous Immunoglobulin

“…Unlike ALS, MMN exhibits asymmetric weakness and affects only the lower motor neuron. The symptoms usually begin in upper limbs [ 1 , 2 ]. Multiple immunomodulatory and immunosuppressive treatments have been used, but the most promising therapeutic strategy is based on the long-term use of intravenous infusion of immunoglobulins (IVIG).…”

“…Multiple immunomodulatory and immunosuppressive treatments have been used, but the most promising therapeutic strategy is based on the long-term use of intravenous infusion of immunoglobulins (IVIG). IVIG is the treatment of choice in NMM (evidence level I) [ 2 ]. NMM does not respond to corticosteroids and immunosuppressive therapy.…”

“…However cyclophosphamide toxicity precludes long-term use, which is usually necessary in patients with MMN. Although plasma exchange and prednisone are well-established therapies in other immune-mediated neuropathies, they are not effective in patients with MMN and may even aggravate symptoms [ 2 ].…”