Anti-N-methyl-D-aspartate receptor-mediated encephalitis in infants and toddlers: case report and review of the literature

Background: Anti-N-methyl-D-aspartate receptor encephalitis is an increasingly well-recognized inflammatory encephalitis in children and adults.

Patient: We report a previously healthy 21-month-old girl who presented with behavioral change, self-mutilatory behavior, and echolalia. Over the ensuing weeks, symptoms progressed to include unilateral upper extremity dystonia, gait impairment, dysphagia, and mutism. Magnetic resonance imaging of the brain showed a tiny area of signal abnormality in the subcortical white matter, but was otherwise normal. Continuous video electroencephalography showed slowing of the background rhythm, but was without epileptiform discharges. Lumbar puncture showed a mild pleocytosis of mixed cellularity; bacterial culture and testing for various viral encephalitides were negative. Serum and cerebrospinal fluid was positive for autoantibodies directed against the N-methyl-D-aspartate receptor, and she was diagnosed with anti-N-methyl-D-aspartate receptor encephalitis. The patient was successfully treated with a regimen of immunotherapy that included dexamethasone, intravenous immunoglobulin, and rituximab. One year after initial presentation, the patient remained symptom-free. We further review the clinical characteristics, results of diagnostic studies, treatment, and outcome of infants and toddlers diagnosed with anti-N-methyl-D-aspartate receptor encephalitis that have been previously reported in the literature.

Conclusion: Anti-N-methyl-D-aspartate receptor encephalitis is relatively common among infants and toddlers and often presents with a pattern of defining characteristics in this age group, particularly the absence of associated tumor.