Magnetic-evoked compound muscle action potential neuromonitoring in spine surgery.
METHODS
Muscle action potentials elicited by paired transcranial magnetic stimulation were recorded during spine surgery in 34 patients. Anesthesia was based on ketamine and fentanyl.


OBJECTIVE
To evaluate the optimal anesthetic regimen to be used for transcranial magnetic stimulation, and to determine the clinical import of magnetic-evoked compound muscle action potentials.


BACKGROUND
Muscle action potential by transcranial magnetic stimulation has been difficult to record under general anesthesia. Ketamine is known to not suppress the muscle responses, although no conclusive clinical study has been reported.


METHODS
Paired transcranial magnetic stimulation was delivered as muscle action potentials were recorded from the limb musculature.


RESULTS
Neuromonitoring was reliable in 56% of total cases and in 82% of the recent cases after reducing fentanyl dosage. Paired magnetic stimulation was an excellent facilitation technique for reliable monitoring. At higher dosages, fentanyl and ketamine decreased the reproducibility of the responses.


CONCLUSIONS
Magnetic-evoked compound muscle action potential neuromonitoring is a sensitive and selective motor pathway monitoring method that covers the entire motor pathway, including the white and gray matter of the spinal cord. Ketamine-based anesthesia is a good choice for this purpose.
Kitagawa
H
H
Department of Orthopaedic Surgery, Toyama Medical and Pharmaceutical University, Japan.
Nakamura
H
H
Kawaguchi
Y
Y
Tsuji
H
H
Satone
T
T
Takano
H
H
Nakatoh
S
S
D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D002648:Child; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009132:Muscles / Q000502:physiology; D009407:Nerve Block; D009469:Neuromuscular Junction; D010812:Physical Stimulation; D015203:Reproducibility of Results; D013122:Spinal Diseases / Q000503:physiopathology* / Q000601:surgery*