Highlights
- •Tc-MEP has low sensitivity in brain tumor surgery.
- •Strong stimulation reaches the deep pyramidal tract producing false negatives.
- •We report characteristics of false-negative cases and stimulation should be minimal to increase sensitivity.
Abstract
Transcranial motor-evoked potential (tc-MEP) monitoring is unreliable for brain tumor
removal due to its low sensitivity. According to previous literature, this is because
transcranial stimulation seems to reach the deep pyramidal tract beyond the operation
point and may thus yield false-negative results, where, although MEP recording is
stable, postoperative motor deficits are encountered. Therefore, we aimed to analyze
the causes for the false-negative results and investigate whether decreasing the stimulation
intensity better reflects the operation point and can improve the sensitivity during
parenchymal brain tumor removal. We assessed 122 patients with parenchymal brain and
intraventricular tumors, who underwent surgery under tc-MEP monitoring in our hospital
between 2011 and 2014. In these patients, the stimulation intensity was fixed at 200 mA.
We detected 11 false-negative cases, while the sensitivity of tc-MEP monitoring was
33.9% and the specificity was 99.0%. Between 2015 and 2016, we examined 68 patients
with parenchymal brain tumors, in whom the stimulation intensity was reduced to an
average of 136.5 mA. Only one case was false-negative, while the sensitivity increased
to 83.3% and the specificity was 98.4%. From these results, we conclude that the intensity
of tc-MEP stimulation should be minimal to precisely reflect the damage to the operated
location. Tc-MEP can be an easy and reliable monitor in brain tumor surgery when used
at proper, lower intensity.
Keywords
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Article info
Publication history
Published online: August 22, 2018
Accepted:
August 12,
2018
Received:
November 22,
2017
Identification
Copyright
© 2018 Elsevier Ltd. All rights reserved.
