(608) Status Epilepticus With a Psychotic Twist: Atypical Presentation of an Autoimmune Encephalitis

Introduction: Antibody-mediated encephalitis, a neuropsychiatric disorder, presents with behavior changes, psychosis, seizures, memory issues, abnormal movements, dysautonomia, and reduced consciousness. We report an anti-NMDAR encephalitis patient with atypical presentation in a patient who recovered with high-dose steroids and Intravenous Immunoglobulin (IVIG).

Description: A 21-year-old African American female with history of seizures and substance abuse, presented with abdominal pain, vomiting, psychosis, unresponsiveness and status epilepticus. CT and MRI Brain scans were negative. Workup ruled out alcohol abuse, sarcoidosis, heavy metal toxicity, Wilson's disease, hereditary coproporphyria, and meningitis. Viral titers were negative except for syphilis, treated with penicillin. She received treatment for MSSA pneumonia. CSF showed lymphocytic predominance with negative cultures and viral tests. Due to refractory seizures on many anti-epileptic drugs, autoimmune encephalitis was suspected. Positive NMDA-R Ab confirmed this. No tumors were found. Treatment with high-dose steroids and IVIG led to recovery.

Discussion: Antibody-mediated encephalitis, a neuropsychiatric disorder, involves symptoms such as headaches, psychiatric issues, sleep disorders, seizures, and decreased consciousness. The recognized types are anti-NMDAR and limbic encephalitis. It is rare, with 5-8 per 100,000 cases. Misdiagnoses include psychosis, schizophrenia, and viral encephalitis. Findings are CSF lymphocytic pleocytosis, infrequent epileptic activity on cEEG, MRI Brain changes, and increased cerebral glucose metabolism on PET. Our case was atypical with status epilepticus without typical MRI findings. Diagnosis was confirmed by detecting serum antibody against GluN1 subunit of NMDAR. Potential triggers like tumors or viral encephalitis were excluded. Abdominal and pelvic ultrasound ruled out ovarian teratoma. Treatment includes methylprednisolone, IVIG, plasma exchange, possible tumor removal, or rituximab if initial treatment fails.

Antibody-mediated encephalitis, often misdiagnosed due to low socioeconomic status, limited healthcare access, and similar symptoms to psychotic disorders, necessitates improved awareness by better healthcare access, early recognition, education, and culturally competent practices.