Lambert-Eaton myasthenic syndrome - diagnosis, pathogenesis and therapy.

Lambert-Eaton myasthenic syndrome (LEMS) describes a rare human autoimmune disorder of the neuromuscular junction (NMJ). Clinically, LEMS patients suffer from characteristic muscle weakness that is caused by the presence of antibodies directed against their voltage-gated calcium channels (VGCC). These channels are localized in the presynaptic membrane of their motor nerve terminals. Binding of autoimmune antibodies to the VGCCs leads to reduced neuromuscular transmission. In approximately 50% of the patients, LEMS is reflected by a paraneoplastic manifestation and most commonly associated with a small cell lung carcinoma (SCLC) whose cells also express VGCCs in their plasma membrane. Better understanding of the pathophysiological mechanisms of LEMS has helped with the development of new diagnostic approaches and has led to targeted symptomatic and immunosuppressive therapy. For LEMS patients with an underlying malignancy, tumor therapy is the first choice to date.