Anti-NMDAR Encephalitis Presenting as Memory Impairment - A Case Report

Dr. Sangeethameena S., Dr. Shankar Ganesh N., Dr. Balaji G., Dr. Hariharan S.

Abstract: Background: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is among the most common autoimmune encephalitides, typically presenting with psychiatric symptoms, movement disorders, seizures, and autonomic dysfunction. Early recognition and immunotherapy are crucial for optimal outcomes. Case Presentation: A 15-year-old female presented with a two-month history of progressive memory impairment and behavioral disturbances. Previously excelling academically with exceptional memorization abilities, she developed severe recent memory deficits, inability to recall learned concepts, and withdrawn behavior with angry outbursts. Two months prior, she experienced new-onset seizures characterized by head and eye deviation to the right, oral secretions, and tonic posturing. Examination revealed recent memory impairment, calculation difficulties, and subtle perioral hyperkinetic movements resembling chewing motions occurring multiple times daily. Investigations: Complete blood count, inflammatory markers, thyroid function tests, and autoimmune panels were unremarkable. Cerebrospinal fluid analysis showed normal biochemistry and cell counts with negative virology. However, both serum and CSF NMDAR antibodies were strongly positive on cell-based assays. Brain MRI, electroencephalography, and computed tomography screening for malignancy were normal. Management and Outcome: The patient received intravenous methylprednisolone pulse therapy for five days followed by tapering oral steroids. Significant clinical improvement was observed, with resolution of memory deficits, behavioral symptoms, and perioral movements. She resumed school attendance confidently without seizure recurrence. Conclusion: This case highlights an unusual presentation of anti-NMDAR encephalitis with predominant memory impairment as the initial feature, absent viral prodrome, and normal neuroimaging. High clinical suspicion is essential for diagnosis, particularly in adolescents presenting with subacute cognitive and behavioral changes with movement abnormalities, even when conventional investigations appear unremarkable.

Keywords: anti-NMDAR encephalitis, autoimmune neurological disorder, adolescent memory impairment, immunotherapy recovery, cognitive and behavioral changes

How to Cite?: Dr. Sangeethameena S., Dr. Shankar Ganesh N., Dr. Balaji G., Dr. Hariharan S., "Anti-NMDAR Encephalitis Presenting as Memory Impairment - A Case Report", Volume 14 Issue 10, October 2025, International Journal of Science and Research (IJSR), Pages: 1068-1071, https://www.ijsr.net/getabstract.php?paperid=SR251020221127, DOI: https://dx.doi.org/10.21275/SR251020221127