Neuroanesthesia & neurocritical care
The Effects of Depth of Anesthesia on Muscle-Recorded Motor Evoked Potentials: A Prospective Observational Study
Authors' conclusion
First, our findings suggest that deeper anesthesia has differential effects on the different muscle groups, with little effect on the hand muscles.
Study context
- Population
- Patients undergoing surgery with Tc-mMEP monitoring under propofol/remifentanil-based TIVAmedian age 18 (14–66) years
- Participants
- 25 patients
- Exposure
- Depth of anaesthesia: BIS 30 vs 40 vs 50
- Outcome
- Tc-mMEP amplitude, latency, AUC and threshold per depth of anaesthesia (BIS)
Methodological detailsrandomly determined BIS sequence direction, linear mixed effects modelling
- Randomly determined BIS sequence direction
- Linear mixed effects modelling
Main finding
As reported in the abstract
Tc-mMEP amplitude and AUC change per 10-point BIS decrease
- AH amplitude decrease, mean
- 12% (95% CI 7.1-16)
- TA amplitude decrease, mean
- 11% (95% CI 6.8-16)
- GAS amplitude decrease, mean
- 12% (95% CI 7.5-16)
- Hand muscles: no significant amplitude change
- 2.8% (95% CI −1.5 to 7.1; P = .201)
- Hand muscles: no significant AUC change
- 4.0% (95% CI −0.4 to 7.6; P = .076)
Observational data: associations, not effects.
Further findings
Tc-mMEP latencies per 10-point BIS decrease
- AH
- 0.03% (95% CI −0.3 to 0.2)
- TA
- −0.2% (95% CI −0.5 to 0.1)
- GAS
- −0.2% (95% CI −0.5 to 0.04)
- Hand
- 0.3% (95% CI 0.04-0.6)
- Latencies changed <0.5% per 10 BIS points decrease
Tc-mMEP threshold, BIS 50 to 30
- Threshold increase (0.8-7; P = .037)
- 3.6%
Original publication
The Effects of Depth of Anesthesia on Muscle-Recorded Motor Evoked Potentials: A Prospective Observational Study. Anesth Analg. Published 20 November 2025. doi:10.
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