title: Suppression of motor evoked potentials by inhalation anesthetics.
abstract: The purpose of this study was to record evoked action potentials from forearm muscles in response to single-shock supramaximal electrical stimulation of motor cortex in room air and under different concentrations (0.5-1.5%) of isoflurane, enflurane, and halothane anesthesia in rats. Anesthesia was induced with a mixture of fentanyl and droperiodol, which was then followed by 10-min inhalation of each gas anesthetic under controlled ventilation. Increasing concentrations of isoflurane (n = 12) caused a progressive increase in onset latency and a decrease in peak-to-peak amplitude and duration. Similar increases in latency and decreases in amplitude and duration occurred under enflurane (n = 10) and halothane (n = 10) anesthesia. The three anesthetics caused a significant latency increase over baseline (room air) values for concentrations from 0.5 to 1.5% (p < 0.01). The amplitude and duration of muscle responses under all three volatile anesthetics at 0.5-1.5% concentrations were significantly lower than baseline (p < 0.01). Isoflurane, enflurane, and halothane anesthesia significantly altered the muscle response evoked by motor cortex stimulation in experimental animals.
authors.affiliation: Division of Neurosurgery, University of Missouri-Columbia Hospital and Clinics, Columbia, Missouri, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Haghighi
authors.forename: R
authors.initials: R
authors.lastname: Madsen
authors.forename: K D
authors.initials: KD
authors.lastname: Green
authors.forename: J J
authors.initials: JJ
authors.lastname: Oro
authors.forename: G R
authors.initials: GR
authors.lastname: Kracke