Anterior opercular syndrome as a first presentation of herpes simplex encephalitis.

We report a 5-year-old girl who presented with fever, drooling, dysphagia, and anarthria. Moreover, voluntary facial movements were disturbed, but the emotional facial movements were completely normal. This clinical phenomenon is known as the anterior opercular syndrome. There was a positive polymerase chain reaction for herpes simplex in the cerebrospinal fluid. The diagnosis herpes simplex encephalitis was supported by both magnetic resonance images (MRI) as by electroencephalogram (EEG). Herpes simplex encephalitis is a rare, but severe, cause of the anterior opercular syndrome that demands treatment as soon as possible in order to prevent high morbidity or mortality. The phenomenon of autonomic-voluntary dissociation, associated with other clinical and radiologic findings related to an underlying neurologic disorder, alerts clinicians to the anterior opercular syndrome as a critical diagnostic observation with time-dependent therapeutic consequences.