RESUMEN
BACKGROUND: Anti-NMDA-receptor-encephalitis is a progressive autoimmune disease with significant mortality if left untreated. CASE DESCRIPTION: A 58-year-old man without previous psychiatric or neurologic history presented at the emergency department after brief loss of consciousness at work. Within a few hours, the patient developed acute neuropsychiatric symptoms, including altered levels of consciousness, aggression, incoherence, change in behaviour, and psychomotor agitation. Initially, additional blood, cerebrospinal fluid and EEG tests showed no abnormalities. Over the course of the following days, catatonia, orofacial dyskinesia and autonomic-function disorder developed, eventually with respiratory insufficiency, necessitating transfer to the intensive-care unit. At this stage, the EEG did show abnormalities, and cerebrospinal fluid analysis showed marginal pleocytosis. The patient was treated with intravenous methylprednisolone and immunoglobins. Anti-NMDA-receptor antibodies were present in the blood and cerebrospinal fluid. Screening for malignancy identified small-cell lung carcinoma, for which the patient was treated with cytostatic agents. CONCLUSION: Acute neuropsychiatric symptoms in a middle-aged patient with no psychiatric medical history are suggestive of an underlying somatic cause. Timely recognition and treatment of anti-NMDA-receptor encephalitis is essential to improve the prognosis.