The epileptogenic properties of the volatile anesthetics sevoflurane and isoflurane in patients with epilepsy

No study comparing epileptogenicity of sevoflurane to other volatile anesth etics has been performed. We compared the epileptogenic properties of sevof lurane to isoflurane in patients with epilepsy. In 24 mentally and/or physi cally disabled patients, 12 with epilepsy and 12 without epilepsy, electroe ncephalograms were recorded under anesthesia with 1.0 minimum alveolar anes thetic concentration (MAC), 1.5 MAC, and then 2.0 MAC sevoflurane or isoflu rane under three ventilatory conditions: (A) 100% oxygen, and end-tidal CO, partial pressure (ETco(2)) = 40 mm Hg, (B) 50% oxygen, 50% nitrous oxide, ETco(2) = 40 mm Hg, and (C) 100% oxygen, ETco(2) = 20 mm Hg. Spike activity was evaluated as a spike-and-wave index (% durations of spike and wave). T he spike-and-wave index increased (P < 0.05) from 1.99% +/- 0.96% during 1. 0 MAC sevoflurane to 6.14% +/- 4.45% during 2.0 MAC sevoflurane in (A) in t he epilepsy group, while no spike activity was observed in the nonepilepsy group. Only a few spikes were observed under isoflurane anesthesia, 0.04% /- 0.04% in (A), with no spikes in (B) and (C). Supplementation with 50% ni trous oxide or hyperventilation (P < 0.05) suppressed the occurrence of spi kes. Sevoflurane has a stronger epileptogenic property than isoflurane, but nitrous oxide or hyperventilation counteracts this specific epileptogenic property.