Sensorial aphasia was detected in a 40-year-old woman who was suffering from acute speech disturbance. Brain magnetic resonance imaging (MRI) findings were normal, but EEG recordings revealed periodic discharges. Lumbar puncture was performed, which resulted in normal cerebrospinal fluid (CSF) findings. Her clinical condition deteriorated to coma. After treatment with acyclovir for two weeks, her clinical picture and EEG findings improved and she was discharged. However, startle reactions developed two days later. She was hospitalized again. Despite normal brain MRI and CSF findings, EEG again showed periodic discharges. She received acyclovir for three weeks, after which all clinical and EEG findings were completely ameliorated. This case report emphasizes the value of EEG in the diagnosis of viral encephalitis in the absence of abnormal MRI and CSF findings.

Keywords: Electroencephalography; encephalitis/diagnosis;Herpes simplex/diagnosis.