Evaluation of reliability of post-tetanic motor-evoked potential monitoring during spinal surgery under general anesthesia.
METHODS
A prospective research.


OBJECTIVE
Compare the reliability of post-tetanic motor-evoked potential (p-MEP) monitoring in the detection of motor injury during spinal surgery with that of conventional MEP (c-MEP).


BACKGROUND
Myogenic MEPs are sensitive to suppression by anesthetics and neuromuscular blockade. Recently, we reported a new technique for MEP recording, called "p-MEP" in which MEP amplitude can be enlarged by tetanic stimulation of peripheral nerve before transcranial stimulation in comparison with that of c-MEP. The purpose of this study is to compare the reliability of p-MEP monitoring in the detection of motor injury during spinal surgery with that of c-MEP.


METHODS
Eighty patients undergoing elective spinal surgery were enrolled in the study. Both c-MEP and p-MEP monitoring were performed throughout the operation in each patient. For recording c-MEPs, transcranial electrical train of five pulses stimulation with an interstimulus interval of 2 milliseconds was performed and compound muscle action potentials were bilaterally recorded from abductor pollicis brevis, abductor hallucis, tibialis anterior, and soleus muscles. For recording p-MEPs, tetanic stimulation (50 Hz, 50 mA, 5 sec) was applied to the left median nerve and bilateral tibial nerves 1 second before transcranial stimulation and compound muscle action potentials were recorded from the same muscles. The false positive, false negative, and accuracy of MEP monitoring in the detection of change in motor function were compared between p-MEP and c-MEP.


RESULTS
At the baseline, success rates of baseline c-MEP and p-MEP recording were 66.3% (53/80) and 92.5% (74/80), respectively. The false positive, false negative, and accuracy of p-MEP monitoring were 0%, 0%, and 100%, respectively, whereas c-MEP were 4%, 20%, and 95%, respectively.


CONCLUSIONS
The results indicate that p-MEP is a more reliable method to detect changes in motor function during spinal surgery under general anesthesia in comparison with c-MEP.
Hayashi
Hironobu
H
Department of Anesthesiology and Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
Kawaguchi
Masahiko
M
Yamamoto
Yuri
Y
Inoue
Satoki
S
Koizumi
Munehisa
M
Ueda
Yurito
Y
Takakura
Yoshinori
Y
Furuya
Hitoshi
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General / Q000379:methods / Q000592:standards*; D002648:Child; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods / Q000592:standards*; D011446:Prospective Studies; D015203:Reproducibility of Results; D013118:Spinal Cord Diseases / Q000503:physiopathology* / Q000601:surgery*; D055815:Young Adult