[Autoimmune myasthenia and Lambert-Eaton myasthenic syndrome. Physiopathologic concepts]

Physiopathological concepts concerning myasthenia gravis and Lambert-Eaton myasthenic syndrome are reported. Autoantibodies are present in both cases. In myasthenia gravis, they are directed against the acetylcholine receptor. The poorly understood physiopathological aspects of this disease are discussed: the lack of correlation between antibody titer and severity, the role of the thymus and the factors triggering the disease. In Lambert-Eaton syndrome, the autoantibodies are directed against the voltage-gated calcium channels of motor nerve terminals. These calcium channels are also present in a cell line derived from a small cell carcinoma, a tumor found in 60% of Lambert-Eaton syndrome patients.