NEUROMAGNETIC SEQUELAE OF HERPES-SIMPLEX ENCEPHALITIS

Spontaneous cortical activity and auditory evoked responses were recor ded with a whole-scalp 122-channel neuromagnetometer from 4 patients a fter left-hemisphere dominant herpes simplex encephalitis and associat ed memory disorders. Spontaneous activity of one patient contained per iodic sharp waves over the left hemisphere; the background activity wa s attenuated. The sources of periodic sharp waves clustered close to t he sources of auditory evoked fields in the temporal lobe. In controls , dominant rhythmic activity over the parietooccipital region had spec tral maximum at 10.6 +/- 0.6 Hz; in patients the dominant rhythmic act ivity peaked at 8.6 +/- 1.8 Hz. The suppression of the parieto-occipit al activity in eyes-open versus eyes-closed condition was smaller in p atients than in controls. The patients' peak spectral frequency was co rrelated with neuropsychological tests reflecting deficient attentiona l capacity. The observed changes probably reflect decreased subcortica l control of the cortical electric activity. (C) 1998 Elsevier Science Ireland Ltd.