Autoimmune encephalitis due to anti-NMDAR antibodies following dog bite and dT vaccination

Abstract

Case presentation. A 17-year-old male patient, following a dog bite and vaccination against diphtheria and tetanus, presented neuropsychiatric symptoms characterized by seizures, altered state of consciousness, right fasciobrachiocrural hemiparesis, dyskinesias, myoclonus, irritability, echolalia, euphoria, sialorrhea, progressive loss of speech, and dysautonomic syndrome. Therapeutic intervention. Metabolic, toxicological, infectious, ischemic, hemorrhagic, and traumatic disorders were ruled out. The electroencephalogram reported a generalized delta rhythm, and pleocytosis and antibodies against the anti-N-methyl-D-aspartate receptor were determined in the cerebrospinal fluid. A paraneoplastic syndrome was ruled out, and a possible adverse event related to vaccination against diphtheria and tetanus was considered. Specific treatment was initiated in the following consecutive order: immunoglobulin, methylprednisolone pulses, and plasmapheresis. Levetiracetam and phenytoin were administered as anticonvulsants; quetiapine and haloperidol were prescribed for the psychotic symptoms. The dysautonomic syndrome was treated with propranolol. Clinical course. After the third plasma exchange session, the patient's alertness and level of attention improved, and the dyskinesias resolved. Psychiatric symptoms disappeared three days after the end of the plasma exchange sessions. Four months after hospital discharge, the patient had recovered all higher mental functions and was walking adequately; however, dysarthria persisted.