Anti-N-methyl-d-aspartate receptor encephalitis in children: Incidence and experience in Hong Kong

• Published in: Brain & development (Tokyo. 1979) 2018-06, Vol.40 (6), p.473-479
• Main Authors: Ho, Alvin Chi-chung, Chan, Sophelia Hoi-shan, Chan, Eric, Wong, Sheila Suet-na, Fung, Sharon Tsui-hang, Cherk, Sharon Wan-wah, Fung, Eva Lai-wah, Ma, Kam-hung, Tsui, Kwing-wan, Yau, Eric Kin-cheong, Wong, Virginia Chun-nei
• Format: Article
• Language: English
• Subjects: Anti-NMDAR encephalitis; Autoimmune encephalitis; Encephalitis; Neuroimmunology; NMDAR antibody
• ISSN: 0387-7604; 1872-7131
• DOI: 10.1016/j.braindev.2018.02.005

The study aims to analyze the incidence, clinical features, investigation findings and treatment outcomes of anti-N-methyl-d-aspartate receptor encephalitis in children from Hong Kong. A retrospective study was carried out on paediatric patients diagnosed with anti-NMDAR encephalitis in Hong Kong from January 2009 to December 2015. Fifteen patients (67% female, 93% Chinese) were identified over seven years and the estimated incidence in Hong Kong was 2.2/million children per year (95% CI 1.2–3.6). The median age of presentation was 12 years (range 1–17 years). The most common symptom groups observed were abnormal psychiatric behavior or cognitive dysfunction (14/15, 93%) and seizures (14/15, 93%), followed by speech dysfunction (13/15, 87%), movement disorders (12/15, 80%), decreased level of consciousness (10/15, 67%) and autonomic dysfunction or central hypoventilation (5/15, 33%). The median number of symptom groups developed in each patient was 5 (range 3–6). All patients were treated with intravenous immunoglobulin and/or steroids. Three patients (20%) with more severe presentation required additional plasmapheresis and rituximab. Outcome was assessable in 14 patients. Among those eleven patients who had only received intravenous immunoglobulin and/or steroids, nine patients (82%) achieved full recovery. One patient (9%) had residual behavioral problem, while another one (9%) who developed anti-NMDAR encephalitis after herpes simplex virus encephalitis was complicated with dyskinetic cerebral palsy and epilepsy. Among those three patients who required plasmapheresis and rituximab, one (33%) had full recovery and two (66%) had substantial recovery. The median duration of follow up was 20.5 months (range 3–84 months). Anti-NMDAR encephalitis is an acquired, severe, but potentially treatable disorder. Ethnicity may play a role in the incidence of anti-NMDAR encephalitis and we have provided a local incidence with the majority of patients being Chinese. The diagnosis of anti-NMDAR encephalitis should be considered in children presenting with a constellation of symptoms including psychiatric and neurological manifestations. Patients may respond to first line immunotherapy. For those who do not, second line therapy is indicated in order to achieve a better outcome.