Alarm criteria for motor evoked potentials

Area of Science:

• Neuroscience
• Surgical Monitoring
• Clinical Diagnostics

Background:

• Transcranial motor evoked potentials (TcMEPs) are crucial for monitoring spinal cord integrity during surgery.
• Interpreting TcMEP changes requires standardized alarm criteria to ensure accurate detection of potential neurological damage.
• Existing alarm criteria vary, necessitating an evaluation of their diagnostic value.

Purpose of the Study:

• To systematically evaluate the diagnostic performance of three common alarm criteria for TcMEP monitoring during spinal surgery.
• To compare the sensitivity and specificity of 50% amplitude reduction, 80% amplitude reduction, and total signal loss as indicators of neurological deficits.

Main Methods:

• A systematic literature review was conducted across PubMed/MEDLINE, Web of Science, and EMBASE (1945-2014).
• Included studies were randomized controlled trials, prospective, or retrospective cohort studies with at least 50 patients undergoing spinal surgery with TcMEP monitoring and immediate postoperative neurological assessment.
• Data from 25 studies involving 9409 patients were analyzed.

Main Results:

• The overall incidence of neurological deficits was 1.82%.
• All reported TcMEP changes demonstrated high overall sensitivity (82.1%) and specificity (95.7%).
• Evaluating specific criteria: 50% amplitude reduction (Sensitivity: 63.2%, Specificity: 96.7%), 80% amplitude reduction (Sensitivity: 71.7%, Specificity: 98.3%), and total signal loss (Sensitivity: 30%, Specificity: 99.3%).

Conclusions:

• No significant difference in sensitivity or specificity was found between 50% and 80% amplitude reduction criteria.
• Total signal loss alarm criterion demonstrated a statistically significant increase in specificity.
• TcMEP monitoring is a highly specific and sensitive tool for detecting neurological defects in spinal surgery.