Autoimmune epilepsy due to N-methyl-d-aspartate receptor antibodies in a child: a case report

INTRODUCTION: Seizures of autoimmune etiology may occur independent of or predate syndromes of encephalitis. We report a child with “pure” autoimmune epilepsy followed up for 7 years to highlight long-term effects of this epilepsy and the importance of early initiation and appropriate escalation of immunosuppression to achieve a good long-term outcome. CASE PRESENTATION: A previously healthy 5-year-old Sri Lankan boy presented with acute, frequent, brief focal seizures of temporal-lobe semiology without clinical and investigatory findings suggestive of central nervous system infection, tumor, structural abnormality, or metabolic causes. His epilepsy showed poor response to increasing doses and combinations of antiseizure medications. Further investigations detected N-methyl-d-aspartate receptor antibodies in serum, but not cerebrospinal fluid. Treatment with intravenous methyl prednisolone and maintenance on mycophenolate resulted in a rapid reduction, with seizure freedom achieved within 5–6 weeks. He relapsed when immunotherapy and anti seizure medications were reduced after seizure freedom for 24 months. This, and subsequent relapses, showed poor response to modification of anti-seizure medications, but treatment with immunotherapy (methyl prednisolone and rituximab) achieved complete seizure freedom. At 7-years of follow-up, he remains free of seizure for over 3 years, and has average academic performance and satisfactory quality of life. CONCLUSIONS: Autoimmune epilepsy is a recognized independent entity. Diagnostic criteria have been suggested for its early recognition and confirmation of diagnosis. Early diagnosis and initiation of immunosuppression, with prompt escalation of treatment when necessary, remains key to good patient outcome.