Movement Occurred During Remimazolam Spinal Surgery Despite BIS Below Sixty

A processed EEG value does not guarantee immobility.

What the paper found

The randomized crossover study compared motor-evoked potentials under propofol and remimazolam with remifentanil. Remimazolam was associated with greater MEP amplitude. One patient had severe movement disrupting surgery even though the bispectral index remained below sixty and neuromuscular blockade was not used.

Limits of the evidence

The sample was small and the movement event cannot estimate its population frequency. MEP preservation, hypnosis and movement suppression involve related but different processes. A single summary index is not a comprehensive measure of all anesthetic effects.

Implications for case review

When reviewing movement, do not infer awareness or inadequate analgesia solely from the event, or exclude them solely because BIS was low. Examine raw recordings, stimulation timing, muscle-relaxant exposure, other drugs and the clinical response. The study illustrates a monitor limitation rather than a universal diagnostic rule.

Source and related reading

Source: PMC12347575, supplied full-text paper. Findings are paraphrased; forensic implications are an interpretation.

Related: Diazepam Was Part of Treatment After Antipsychotic-Associated Movement Symptoms During Alcohol Withdrawal.