Cutoff Points, Sensitivities, and Specificities of Intraoperative Motor-Evoked Potential Monitoring Determined Using...

Area of Science:

• Neurosurgery
• Neuromonitoring
• Clinical Neurophysiology

Background:

• Intraoperative motor-evoked potential (MEP) monitoring is standard in neurosurgery.
• However, the interpretation of MEP results and their predictive value for postoperative deficits remain debated.

Purpose of the Study:

• To establish precise cutoff points for MEP amplitude reduction to predict and prevent neurological deficits.
• To optimize MEP monitoring protocols based on surgical procedure type and stimulation method.

Main Methods:

• MEP monitoring was conducted during 484 neurosurgical operations (spinal, cerebral aneurysm, brain tumor).
• Compound muscle action potential (CMAP) normalization was used to mitigate the effects of muscle relaxants.
• Receiver operating characteristic (ROC) analyses determined cutoff points, sensitivity, and specificity.

Main Results:

• For spinal operations, 77.9%-80.6% amplitude reduction indicated motor palsy with high sensitivity and specificity.
• Aneurysmal operations showed 100% sensitivity with cutoff points around 70% amplitude reduction.
• Brain tumor operations under direct stimulation demonstrated 100% sensitivity and specificity with cutoff points around 83.5%-86.3%.

Conclusions:

• Recommended MEP amplitude reduction cutoff points are 80% for brain tumor, 75% for spinal, and 70% for aneurysmal operations.
• These specific thresholds, particularly with CMAP normalization, enhance the predictive accuracy of MEP monitoring.
• Implementing these tailored cutoff points can significantly improve patient safety and neurological outcomes in neurosurgery.