[The temporal dynamics of EEG changes in the early phase of herpes simplex encephalitis]

In 19 patients with herpes simplex encephalitis 64 EEG examinations and 36 CT scans have been performed within the first two weeks after onset of clinical symptoms. During the first 10 days periodic discharges were present in 12 patients. At this time CT scan was negative in 5 of them. Five of 7 patients without but only 4 of 12 patients with this EEG pattern survived without clinical abnormalities. Five patients with periodic discharges died during the acute stage of the illness. In patients with poor outcome including major clinical deficit or death periodic discharges were present during successive investigations until day 14. In the group of patients with good clinical improvement these EEG changes were only detected in a single recording until day 7. Periodic discharges have to be considered as an indicator of a poor prognosis whenever they are present for a longer period.