OBJECTIVETo investigate electroencephalographic (EEG) characteristics of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis in children.

METHODClinical data of 28 children diagnosed as anti-NMDAR encephalitis were retrospectively analyzed for EEG characteristics in different periods and severity of disease and outcome.

RESULTAmong the 28 patients with anti-NMDAR encephalitis, 15 were males and 13 were females. Their age at disease onset ranged from 1 year 3 months to 12 years 4 months. Patients were divided into mild group (5 cases) and severe group (23 cases). In the different stage of the disease, occipital background activity of the EEG was preserved in more than half of patients. Accompanied by the evolution of disease course, the occipital background activity and slow waves gradually recovered to normal. In the peak phase of disease, occipital background activity in the awake state was preserved in 4/5 patients of the mild group and 9/17 patients of the severe group. Alpha and theta band rhythms in non-rapid eye movement (NREM) sleep existed in 77% (17/22) patients. EEG monitoring showed delta brushes in 2 cases, and the delta brushes were mixed with background fast waves in one case; 71% (20/28) patients had epileptiform discharges in EEG during the course, and among them, 6 patients had secondary epilepsy.

CONCLUSIONThe background activity in the awake state and abnormal diffuse slow waves of EEG were evolved and gradually recovered during the course of the disease. Regardless milder or severe illness condition, occipital background activity was still preserved during different stages in most patients. Alpha and theta rhythms in NREM sleep might represent a relatively overt EEG characteristic. The presence of delta brush in EEG was rare, and sometimes they were difficult to be distinguished from fast wave activities caused by drugs. The presence of epileptiform discharges in EEG suggested the possibility of secondary epilepsy.