Lambert–Eaton Myasthenic Syndrome

LEMS is a rare autoimmune disorder characterized by impaired presynaptic acetylcholine release at the neuromuscular junction, often associated with small-cell lung carcinoma. Clinical manifestations include proximal muscle weakness, autonomic dysfunction, and fatigability. Pathophysiology involves autoantibodies targeting voltage-gated calcium channels, leading to reduced neurotransmitter release. Diagnosis relies on electrophysiologic studies, serology for anti-VGCC antibodies, and tumor screening. Management includes immunotherapy, symptomatic therapy with 3,4-diaminopyridine, and treatment of underlying malignancy; prognosis improves with early tumor detection and immunomodulation.