The Effects of Depth of Anesthesia on Muscle-Recorded Motor Evoked Potentials: A Prospective Observational Study.

Summary: When doctors perform surgery near the spine, they use electrical signals to make sure the spinal cord is safe. Sometimes, these signals give false alarms, making doctors think there is a problem when there isn't. Doctors wondered if the deep sleep medicine (anesthesia) was causing these false alarms.

In a study of 25 patients, they found that deeper sleep made the electrical signals weaker in the legs, but not in the hands. Because of this, doctors shouldn't use the hand signals to judge what is happening in the legs. Also, they found that checking the starting point of the signal (the threshold) is a much better way to avoid false alarms than checking the size of the signal.