title: Evaluation of the applicability of sevoflurane during post-tetanic myogenic motor evoked potential monitoring in patients undergoing spinal surgery.
abstract: OBJECTIVE
  Recent evidence has indicated that post-tetanic motor evoked potentials (p-MEPs) can be used to improve the reliability of the monitoring of motor function during spinal surgery. However, data on p-MEP monitoring are limited to those in subjects under propofol anesthesia. The present study was conducted to assess the applicability of sevoflurane during p-MEP monitoring in patients undergoing spinal surgery.
  
  
  METHODS
  Thirty-five patients undergoing spinal surgery under sevoflurane anesthesia were enrolled in the study and classified as being without preoperative motor deficits (n = 25) or with preoperative motor deficits (n = 10). For conventional MEP (c-MEP), transcranial train-pulse stimulation was delivered and the compound muscle action potentials were bilaterally recorded from the abductor pollicis brevis, abductor hallucis, tibialis anterior, and soleus muscles. For p-MEP, tetanic stimulation (50 Hz, 50 mA stimulus intensity) for 5 s was applied to the bilateral median and left tibial nerves 1 s prior to transcranial stimulation.
  
  
  RESULTS
  The amplitudes of p-MEP were significantly higher in all muscle recording sites than those of c-MEP in patients without motor deficits, whereas these amplitudes were significantly higher in only four of the eight muscles in patients with motor deficits (P < 0.05). The success rates of c-MEP and p-MEP recording were 48% and 64%, respectively, in patients without motor deficits and 30% and 60%, respectively, in patients with motor deficits. There were no statistically significant differences in success rates between c-MEP and p-MEP recording.
  
  
  CONCLUSIONS
  Although the application of tetanic stimulation prior to transcranial stimulation did not significantly increase the success rates of MEP recording, it significantly enlarged MEP amplitude under sevoflurane anesthesia in patients without preoperative motor deficits.
authors.affiliation: Department of Anesthesiology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Hayashi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Abe
authors.forename: Yuri
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Satoki
authors.initials: S
authors.lastname: Inoue
authors.forename: Munehisa
authors.initials: M
authors.lastname: Koizumi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takakura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Furuya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D002648:Child; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D018482:Muscle, Skeletal / Q000502:physiology; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D000077149:Sevoflurane; D013122:Spinal Diseases / Q000601:surgery; D013131:Spine / Q000601:surgery*; D013979:Tibial Nerve / Q000502:physiology; D055815:Young Adult
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane