[Althesin-induced EEG changes in patients with central nervous system lesions]

The EEG changes produced by Althesin (75 microliter/kg intravenously administered over 60 sec) were evaluated in 18 unpremedicated patients wih CNS diseases who were scheduled for cerebral angiography. Three parameters were analyzed: the EEG patterns of anaesthesia, the appearance of a fast activity during stabilized burst suppression (Level V), and enhancement of the registered epileptiform abnormalities. The EEG depth of anaesthesia was correlated with the EEG pattern at rest and the preexisting neurological signs. The 15 Hz fast activity which occurred during the suppression phase of Level V was recorded unilaterally over the healthy hemisphere, while it was observed bilaterally in a case involving lesion of the midline structures. The exaltation of the epileptiform EEG discharges following Althesin administration suggests that this agent might be utilized as a convenient provocative test in the diagnosis of epilepsy.