RT Journal Article SR Electronic T1 Delta brush on EEG: a characteristic EEG finding in autoimmune encephalitis JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e249899 DO 10.1136/bcr-2022-249899 VO 16 IS 2 A1 Saleem, Shafaq A1 Siddiqui, Sarwar Jamil A1 Qureshi, Faizan Abdullah A1 Kanwar, Dureshahwar YR 2023 UL http://casereports.bmj.com/content/16/2/e249899.abstract AB A woman in her late 20s was admitted via the emergency department in the psychiatric ward with acute-onset behavioural changes and suicidal thoughts in the past 2 weeks. Workup revealed positive N-methyl-D-aspartate (NMDA) receptor antibodies in cerebrospinal fluid and electroencephalogram (EEG) showing a specific pattern of delta brush on bilateral frontal regions. Other investigations were unremarkable. The patient was started on intravenous methylprednisolone 1000 mg for 5 days with oral steroids. She responded on steroids. She has been recommended for workup for teratoma/mediastinal tumours with NMDA receptor encephalitis is an autoimmune disorder predominantly affecting women of childbearing age. Delta brush pattern on EEG is specific for NMDA receptor encephalitis hence can be used as a diagnostic tool. It is advisable to investigate any patient with the presentation of mental deterioration for pathological causes. However, treatment with immunotherapy increases the chance of survival and may prevent cognitive impairment.