Association of Lambert-Eaton Myasthenic Syndrome and First Episode Psychosis: A Case Report

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune neuromuscular junction disorder characterized by proximal weakness, autonomic dysfunction, and areflexia associated with antibodies against voltage-gated calcium channels (VGCCs). Psychotic symptoms can occur in many autoimmune neurological disorders but they have rarely been observed in myasthenic syndromes. We report the case of a 21-year-old woman with primary autoimmune LEMS due to anti-VGCC antibodies subtype P/Q, who developed psychotic symptoms 3 years after the onset of motor symptoms. These symptoms decreased after every cycle of monthly intravenous immunoglobulin therapy. Different causes of reversible psychosis were excluded, such as autoimmune encephalitis. Due to a worsening of the patient's muscle strength, and the psychotic episodes, the patient received several treatments including an admission to a neurology unit. To our knowledge, this is the first described case of psychotic symptoms associated with LEMS. We speculate that VGCC antibodies could have a role in the development of mental symptoms, although additional hypotheses are also discussed.