J Korean Neurosurg Soc.  2017 Jul;60(4):475-480. 10.3340/jkns.2016.0506.006.

An Electrode Configuration for Recording Muscle Motor Evoked Potentials in the Upper Extremities during Intraoperative Neurophysiological Monitoring

• Choi YD
• Jin SH
• Kim CH
• Kwak GH
• Kim BE
• Chung CK

• KMID: 2387887
• DOI: http://doi.org/10.3340/jkns.2016.0506.006

Abstract

OBJECTIVE
The main aim of the present study is to examine the electrode configurations used to record the muscle motor evoked potential (mMEP) in the upper extremities during surgery with the goal of producing a high and stable mMEP signal, in particular among the abductor pollicis brevis (APB), abductor digiti minimi (ADM), and across the APB-ADM muscles, which have been widely used for the mMEP in the upper extremities.
METHODS
Thirty right-handed patients were recruited in this prospective study. No patients showed any adverse events in their mMEP signals of the upper extremities during surgery. The mMEPs were recorded independently from the signals for the APB and ADM and for those across the APB-ADM.
RESULTS
The mMEP amplitude from across the APB-ADM was statistically higher than those recorded from the APB and ADM muscles. Moreover, the coefficient of variation of the mMEP amplitude from across the APB-ADM was smaller than those of mMEP amplitude recorded from the APB and ADM muscles.
CONCLUSION
The mMEP from across the APB-ADM muscles showed a high yield with high stability compared to those in each case from the APB and ADM muscles. The configuration across the APB-ADM muscles would be best for mMEP recordings from the upper extremities for intraoperative neurophysiological monitoring purposes.

Keyword

Motor evoked potential; Intraoperative neurophysiological monitoring; Upper extremity; Abductor digiti minimi; Abductor pollicis brevis; Across APB-ADM

MeSH Terms

Electrodes*
Evoked Potentials, Motor*
Humans
Intraoperative Neurophysiological Monitoring*
Muscles
Prospective Studies
Upper Extremity*

Figure

• 

  Fig. 1 Example of mMEP recorded from APB, ADM and across the APB-ADM muscles. The columns from left to right show mMEPs as recorded from the across-APB-ADM, APB and ADM locations, respectively. The mMEPs at 12:29:11 correspond to the mMEPs under a muscle relaxant. The mMEPs at 13:50:19 correspond to the baseline mMEPs, with the following mMEPs measured during surgery. The mMEP amplitudes recorded across APB-ADM muscles were the largest compared to the remaining recording sites, and the morphology appeared to be relatively consistent over time. mMEP: motor evoked potential, APB: abductor pollicis brevis, ADM: abductor digiti minimi.

• 

  Fig. 2 Boxplot of the mMEP amplitude recorded from the APB, ADM and across the APB-ADM muscles. The y-axis indicates the mMEP amplitude (unit: μV). Median mMEP amplitude values recorded from the APB, ADM and across the APB-ADM were 1853.9 μV, 893.0 μV, 2238.0 μV, respectively. Wilcoxon signed-rank tests with Bonferroni correction showed significant differences between APB and ADM (*p<0.01, r=0.74) and between the ADM and across-APB-ADM values (†p<0.01, r=0.83). But between the APB and across-APB-ADM values, there were not showed significant differences (‡p<0.05, r=0.49). mMEP: motor evoked potential, APB: abductor pollicis brevis, ADM: abductor digiti minimi.

• 

  Fig. 3 Boxplot of the coefficient of variation (CV) of the mMEP amplitudes recorded from the APB and ADM and from across the APB-ADM muscles. The median CV of recorded from the APB, ADM and across-APB-ADM locations were 0.23, 0.31, and 0.17, respectively. Wilcoxon signed-rank tests with Bonferroni correction showed a larger amplitude recorded from across the APB-ADM muscles compared to that recorded from ADM (*p<0.01, r=0.65). No significant differences were detected between APB and ADM and between APB and across the APB-ADM. mMEP: motor evoked potential, APB: abductor pollicis brevis, ADM: abductor digiti minimi.

Reference

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