Pediatric Anti-NMDAR Encephalitis in Southern China: Analysis of 107 Cases

Background: Research on pediatric anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is limited. We studied clinical features of children with anti-NMDAR encephalitis in southern China.Methods: Pediatric anti-NMDAR encephalitis between 2014 and 2019 from one tertiary medical center was analyzed. The Modified Rankin Scale (mRS) score was adopted to evaluate outcomes.Results: 107 children (M/F=50/57; mean onset age=6.3 y) with anti-NMDAR encephalitis were involved. Boys significantly showed earlier onset age, higher ratio of fever, longer hospital day, more courses of steroid treatment, higher mRS score after treatment. 48.6% of patients had prodromal events with infectious events most common. The most common symptom at onset and during whole course was seizures and psychiatric symptoms respectively. Initial median white cell count of cerebral spinal fluid (CSF) was 22.0x106/L. 12.1% of patients had positive herpes simplex virus DNA of CSF. All patients had CSF positive NMDAR antibodies, although 86.9% of patients had serologically positive. 9.3% of patients had overlapped other neuronal antibodies. Electroencephalograph showed abnormalities with slow wave (95.3%) and epileptic activity (41.5%). Delta brush was revealed in 3.8% of patients. 36.4% of patients had lesions in brain MRI, with local lesions most common. No tumor was found in all. 84.9% of patients responded well to the first line therapy (steroid plus immunoglobulin), while 12 patients accepted second-line therapy (Rituximab) with 91.7% of effective rate. 12.1% of patients relapsed. 2 male patients died. The median length of hospital stay was 28 days. The mRS score was significantly improved after treatment. 51.0% of patients had a full recovery. 76.6% of patients had mild neurological disability (mRS≤2). Male, speech disorder, initial score of mRS and administration of second-line therapy were independent risk factors associated with the outcome.Conclusions: Of pediatric anti-NMDAR encephalitis in southern China: the mean onset age was about 6-year-old, earlier in boys; boys remained slower to recover and with a worse prognosis; the most common respective symptom at onset and during whole course was seizures and psychiatric symptoms; combination with tumor was rare; most patients respond well to the immunotherapy; relapse and fatality rate were relatively low; most patients had a good prognosis.