Lambert-Eaton Myasthenic Syndrome: A Review

Lambert-Eaton myasthenic syndrome (LEMS) is an auto-immune disorder caused by neuromuscular transmission failure, and is a representative pre-neuromuscular junctional disorder. The auto-immune antibody is anti-P/Q-type voltage-gated calcium channel (P/Q-type VGCC) antibody detected in approximately 80 to 90% of LEMS patients. Approximately 60% of LEMS patients have small cell lung cancer (SCLC), approximately 10% of patients have other malignant tumors, and the remaining 30% have no malignancy. Thus, the therapeutic strategy for LEMS depends on the presence of a malignant tumor. LEMS with a malignant tumor is also considered to be a representative paraneoplastic neurological syndrome. Recently, new chemotherapeutic drugs for malignant tumors including SCLC have been developed. In cases with no malignancy, several new immune-mediated therapies have become available. Therefore, we can expect improved therapeutic responses for this disorder.