Seizure characteristics and neurological outcomes in pediatric anti-NMDAR encephalitis: a cohort study from Southern China

This study aimed to investigate seizure characteristics, treatment and outcome of pediatric anti-NMDAR encephalitis in southern China. Clinical data of pediatric patients diagnosed with anti-NMDAR encephalitis were were retrospectively analyzed. Neurological disability and seizure severity were assessed using the mRS score and NHS3 scale, respectively. Among 119 children with anti-NMDAR encephalitis, 74.8% (89/119) presented with seizures, with SE in 19.3% (23/119). The relapse rate was significantly higher in patients with seizures during the acute stage (19.1%, 17/89) compared to those without seizures (3.3%, 1/30) (P = 0.041). The mean NHS3 score for seizures during the acute stage was 7.9 ± 0.9. Patients with > 3 seizure episodes had higher mRS pre-immunotherapy, required longer hospital stays and received more courses of intravenous methylprednisolone (IVMP) or intravenous immunoglobulin (IVIG) courses and were more likely to require Rituximab. EEG abnormalities were observed, including background slowing in all cases, epileptic discharges (37.0%), and extreme delta brush in 8.4%. 53.9% (48/89) of patients with seizure received anti-seizure medications (ASMs), 72.9% (35/48) of whom were treated with monotherapy. Seizure remission was achieved in 95.8% (46/48) within one year; 25.0% (12/48) discontinued ASMs after a median of 6.0 months (IQR 3.5, 15.0 months) without seizure recurrence, while 75.0% (36/48) continued ASMs at the last follow-up, with 5.6% (2/36) still experiencing seizures despite CSF anti-NMDAR antibodies turned negative. Patients with status epilepticus (SE) had longer diagnostic delays and higher pre-immunotherapy mRS scores, required more IVIG courses, but showed a similar prognosis compared with non-SE patients. Seizures are common in pediatric anti-NMDAR encephalitis; patients with more than three seizure episodes had higher mRS pre-immunotherapy and required more intensive treatment; Approximately half of the patients required ASMs, with 95.8% achieving remission within one year. The relapse rate was significantly higher in patients with seizures during the acute stage compared to those without seizures. Patients with SE had higher mRS pre-immunotherapy and required more IVIG courses, but their prognosis was similar to that of non-SE patients.