[Herpes simplex encephalitis in neuro-surgery. Electro-encephalographic contribution to early diagnosis (author's transl)].

The electroencephalographic (EEG) signs of acute necrotizing encephalitis are always focalized initially. In over 80% of the cases, the EEG shows local periodical activity with a characteristically short interval between repetitive paroxysms. This was demonstrated by the study of 17 personal observations in which herpes simplex virus was unequivocally identified as the causal agent. This EEG pattern belongs to the general group of "periodical activities". It is an early but transient finding. When observed in an acute clinical picture with fever and encephalic symptoms, it is a major diagnostic feature and should lead to immediate active therapy (neuro-surgery or chemotherapy).