Weakly Positive Anti-NMDAR Encephalitis Following a Gastrointestinal Prodrome: A Case Report.

Anti-NMDAR encephalitis is an autoimmune neurological disorder characterized by neuropsychiatric symptoms, seizures, and altered consciousness. We report a 35-year-old female who presented in March 2025 with gastrointestinal symptoms followed by encephalopathy and seizures. Investigations revealed lymphocytic cerebrospinal fluid (CSF), diffuse slowing on electroencephalography, and parieto-occipital cortical changes on MRI, with weakly positive anti-NMDAR antibodies. The patient showed significant clinical improvement following corticosteroids and plasma exchange. This case highlights the diagnostic challenge of autoimmune encephalitis presenting with gastrointestinal prodrome and elevated inflammatory markers mimicking infection.