title: The application of tetanic stimulation of the unilateral tibial nerve before transcranial stimulation can augment the amplitudes of myogenic motor-evoked potentials from the muscles in the bilateral upper and lower limbs.
abstract: BACKGROUND
  Recently, we reported a new technique to augment motor-evoked potentials (MEPs) under general anesthesia, posttetanic MEP (p-MEP), in which tetanic stimulation of the peripheral nerve before transcranial stimulation enlarged amplitudes of MEPs from the muscle innervated by the nerve subjected to tetanic stimulation. In the present study, we tested whether tetanic stimulation of the left tibial nerve can also augment amplitudes of MEPs from the muscles which are not innervated by the nerve subjected to tetanic stimulation.
  
  
  METHODS
  Thirty patients undergoing spinal surgery under propofol-fentanyl anesthesia with partial neuromuscular blockade were examined. For conventional MEP (c-MEP) recording, transcranial stimulation with train-of-five pulses was delivered to C3-4, and the compound muscle action potentials were bilaterally recorded from the abductor pollicis brevis, abductor hallucis (AH), tibialis anterior, and soleus muscles. For p-MEP recording, tetanic stimulation (50 Hz, 50 mA of stimulus intensity) with a duration of 5 s was applied to the left tibial nerve at the ankle 1 s before transcranial stimulation. Transcranial stimulation and recording of compound muscle action potentials were performed in the same manner as c-MEP recording. Amplitudes of c-MEP and p-MEP were compared using Wilcoxon's signed rank test.
  
  
  RESULTS
  Amplitudes of p-MEPs from the left AH muscle innervated by the left tibial nerve with tetanic stimulation were significantly larger compared with those of c-MEPs. Amplitudes of p-MEPs from the bilateral abductor pollicis brevis and soleus muscles and right AH and tibialis anterior muscles, which were not innervated by the left tibial nerve with tetanic stimulation, were also significantly larger compared with those of c-MEPs.
  
  
  CONCLUSIONS
  In patients under propofol and fentanyl anesthesia with partial neuromuscular blockade, the application of tetanic stimulation to the left tibial nerve augmented the amplitudes of MEPs from the muscles without tetanic nerve stimulation and those with stimulation.
authors.affiliation: Department of Anesthsiology, 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: 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: Yurito
authors.initials: Y
authors.lastname: Ueda
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takakura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Furuya
mesh_terms: D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000502:physiology*; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor; D005121:Extremities; D005260:Female; D005283:Fentanyl / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D019148:Neuromuscular Blockade; D015742:Propofol / Q000494:pharmacology; D013979:Tibial Nerve / Q000502:physiology*
chemical_list: D005283:Fentanyl; D015742:Propofol