Background/Purpose: The discovery of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis heralded a new class of neuropsychiatric illnesses mediated by autoantibodies, known collectively as autoimmune encephalitis. The clinical characteristics and potential triggers in pediatric cases of anti-NMDAR encephalitis are not well understood. In North America, diagnosis and immunomodulation of children with anti-NMDAR encephalitis are often undertaken by multi-disciplinary teams that include rheumatologists. Our objective is to characterize presentations and potential etiologies of childhood-onset anti-NMDAR encephalitis at a large tertiary urban center that covers a multi-state catchment area.

Methods: After IRB approval, we retrospectively reviewed the initial presentation of patients with anti-NMDAR encephalitis at Texas Children’s Hospital between 2009 and 2021.

Results: Our cohort included 76 children who were predominantly female (49/86, 64%) and Hispanic (50/76, 66%). The mean age of onset was 9.5 5.6 years old with a bimodal distribution. This was a larger number than presented annually with neuropsychiatric SLE during the study period (6 vs 2 per year). All children with anti-NMDAR encephalitis had behavioral/cognitive symptoms, 60 (79%) had seizures, 55 (73%) had speech abnormalities, 51 (67%) had movement disorders, and 46 (61%) had memory deficits. Regarding potential etiologies, 4 (5%) had ovarian teratoma (mean age 12.5 1.5 years), and 9 (12%) had a recent history of herpes simplex virus (HSV) encephalitis (mean age 3.7 1.4 years). The remaining 63 (83%) patients had no known causative trigger (mean age 10.1 0.7 years).

Conclusion: In a large single-center pediatric cohort of anti-NMDAR encephalitis, most cases were unrelated to HSV encephalitis or ovarian teratomas. Age of onset had a bimodal distribution representing pre-pubertal and post-pubertal. Female and Hispanic children were disproportionally affected compared to the general inpatient population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-and-demographic-characteristics-of-children-with-anti-nmdar-encephalitis/