Sevoflurane is epileptogenic in healthy subjects at surgical levels of anesthesia

Objective: To investigate EEG effects of three escalating concentrations of sevoflurane and propofol in single-agent anesthesia on healthy subjects. Methods: Four-channel EEG was continuously recorded at 1, 1.5, and 2 minimum alveolar concentration ( MAC)/effective plasma concentration 50 (EC50) levels of either sevoflurane or propofol anesthesia in 16 men, 8 subjects in each group. Each concentration level lasted for 30 minutes. EEG was first visually analyzed. In quantitative EEG analysis, the 95% spectral edge frequency (SEF95) and peak frequency (PF) were determined after fast Fourier transformation. Results: Epileptiform discharges occurred in all eight subjects at 1.5 and 2 MAC levels of sevoflurane anesthesia. Three subjects showed electrographic seizures at 2 MAC level, in one case accompanied with clinical seizures despite muscle relaxation. Propofol did not produce remarkable epileptiform EEG phenomena at any level of anesthesia. Suppression and slowing of EEG activity were evident for both drugs with increasing concentration. Owing to the high incidence of epileptiform events in the sevoflurane group at 1.5 and 2 MAC, the SEF95 and PF values were higher ( p < 0.001) compared with propofol. Within the sevoflurane group, these values were higher at the 2 than at the 1.5 MAC level ( p values ranged between < 0.001 and 0.019). Conclusions: Sevoflurane consistently produces epileptiform discharges and is dose dependently epileptogenic at surgical levels of anesthesia.