Relapsing symptoms post herpes simplex virus 1 (HSV) encephalitis (HSVE) usually occur a few weeks after viral therapy and represent either 1) a true viral relapse of HSVE (CSF PCR positive for HSV, new necrotic lesions on brain MRI, and response to acyclovir therapy) or 2) a disorder postulated to be immune-mediated (CSF negative for HSV, no new necrotic lesions, and no response to acyclovir).(1,2) It has been suggested that this immune-mediated disorder may be related to NMDA receptor (NMDAR) antibodies,(3) and we recently reported a child in whom relapsing symptoms post HSVE were the presentation of anti-NMDAR encephalitis.(4) We report an adult with this disorder, demonstrate that synthesis of NMDAR antibodies began after HSVE, and show that relapsing symptoms were due to steroid-responsive anti-NMDAR encephalitis.
