Successful treatment of two paediatric cases of anti-NMDA receptor encephalitis with cyclophosphamide: the need for early aggressive immunotherapy in tumour negative paediatric patients.

We describe the clinical course and treatment of three unrelated female patients ranging in age from 27 months to 14 years with anti-NMDA receptor encephalitis. The third case is reported as an addendum to the paper. None of the cases were paraneoplastic. All received initial immunotherapy consisting of steroids and IVIg, and two of them received 3 and 8 plasma exchanges respectively, without consistent or sustained clinical improvement. All three girls were then treated with monthly cycles of Cyclophosphamide. All had resolution of their movement disorder and a dramatic and sustained clinical improvement of their other symptoms in the domains of cognition, language and behaviour. The clinical improvement began after the first cycle in two and the second cycle in the third and continued with the subsequent cycles. None developed side-effects of treatment. In light of the recent review of the condition and our own clinical experience in the paediatric age group, we propose that second line immunotherapy should be considered early after failure of first line immunotherapy.