The development of one case of proved necrotising Herpes-simplex encephalitis (Herpes-virus hominis Typ I) will be demonstrated with the help of daily encephalographic and 5 computertomographic studies. After the appearance of periodic complexes in the EEG there could be noticed with a difference of 24 hours a beginning and further on a progressive blurred hypodensity in the CT. The maximum of the periodic activity in the EEG exactly correlated to the beginning and later expansion of the anatomo-pathological changes. No expansion of the periodic activity could be registered in other areas of the brain. Yet there was spontaneous periodic activity in different brain areas, where new regions of hypodensity would be found in the CT. The additional appearance of new periodic complexes with different localisation and the demonstration of new hypodensities in the CT during the therapy of a Herpes-simplex-encephalitis must be valued as a bad prognosis of the illness.
