An Unusual Case of Herpes Simplex Viral Encephalitis Following Acute Retinal Necrosis after Administration of a Systemic Steroid

Acute retinal necrosis (ARN), a viral retinal disease with poor visual prognosis, following herpes simplex encephalitis (HSE) are uncommonly seen, and there has been no case yet reported of the reverse situation. We herein present the reverse situation, an immune-competent patient with HSE following ARN. A 57-year-old man who had been under steroid therapy for retinal vasculitis the prior two weeks, presented with abrupt confusion and high fever. His cerebrospinal fluid study and brain magnetic resonance imaging revealed typical HSE. Ophthalmic examination and polymerase chain reaction of the vitreous specimen revealed ARN by herpes simplex virus type 2. Intravenous acyclovir treatment improved his encephalitis symptoms and retinal necrosis. This case implies that ARN may be a risk factor for HSE and the virus may reach the brain from the eye. Inappropriate administration of a systemic steroid may exacerbate herpes viral infection in the retina, with subsequent spread to the brain.