Abstract
Acute secondary neurological deterioration after herpes simplex encephalitis has been reported. An immune-mediated process is thought to be responsible for some cases. The authors report the case of an infant who presented with fever, irritability, and orofacial involuntary movements, 15 days after herpes encephalitis onset. Polymerase chain reaction for herpes simplex virus was negative, and the magnetic resonance imaging revealed extensive white matter lesions. Chorea appeared only 11 days later. Raised immunoglobulin G index with oligoclonal bands and spreading of white matter lesions corroborated an immune-mediated etiology. An interferon production deficit was also detected. This case alerts that this form of ‘‘relapse’’ appears earlier than previously reported. A high level of suspicion is needed in the presence of atypical neurological deterioration and early white matter lesions should be considered as a warning sign. This case is also relevant because it associates, for the first time, an immune-mediated ‘‘relapse’’ to an interferon production deficit.