Myasthenia gravis and myasthenic syndromes .2. Lambert-Eaton myasthenic syndrome, congenital myasthenic syndromes and botulism

This review discusses the Lambert-Eaton myasthenic syndrome (LEMS), the congenital myasthenic syndromes and botulism. LEMS is a paraneoplastic/autoimmune neuromuscular disorder characterized by fluctuating weakness of voluntary muscles and disturbed function of the autonomic nervous system. Circulating antibodies against the presynaptic voltage-gated calcium channels are found in the majority of patients. Treatment includes enhancement of neuromuscular transmission with aminopyridines and anticholinesterases, medical immunosuppression and, if a tumor has been found, antitumor treatment. The congenital myasthenic syndromes represent the rapidly growing field of knowledge of the numerous disturbances of neuromuscular transmission. Symptoms are frequently present soon after birth but can occur even in the second decade of life. They are mainly of recessive autosomal inheritance. Diagnostic tests include electrophysiological and morphological studies from muscle biopsy specimens and in vitro. Treatment options depend on the underlying pathophysiology. Botulism is also a presynaptic neuromuscular transmission defect, and has now become very rare. The disease may be life-threatening and treatment mainly consists of toxin neutralization with antitoxins and supportive care within an intensive care unit.