A first case association of Lambert-Eaton Myasthenic Syndrome and First Episode Psychosis: a case report

Background: Lambert-Eaton Myasthenic Syndrome is an autoimmune neuromuscular junction disorder characterized by proximal weakness, autonomic dysfunction and areflexia associated with antibodies against voltage-gated calcium channels. Psychotic symptoms can take place in many auto-immune neurological disorders, but their occurrence in myasthenic syndromes has rarely been observed. Case presentation : We report a case of a 21-year-old female with primary autoimmune Lambert-Eaton Myasthenic Syndrome due to anti-voltage-gated calcium channels antibodies subtype P/Q, who developed psychotic symptoms 3 years after motor symptoms onset. With monthly administration, these symptoms improved after every cycle of Intravenous Immunoglobulin therapy. Different causes of reversible psychosis were excluded, such as autoimmune encephalitis. Owing to muscle strength worsening and psychotic episodes, the patient was put on several treatments including one admission to a Neurology unit. Conclusions: This is, to our knowledge, the first described case of a psychotic syndrome associated with Lambert-Eaton Myasthenic Syndrome. We speculate that voltage-gated calcium channel antibodies could have a role in the development of mental symptoms, however further hypotheses are discussed.