Magnesium Sulfate-Induced Motor Evoked Potential Changes

ABSTRACT

Motor evoked potentials (MEPs) are commonly used during neurophysiologic intraoperative monitoring. Anesthetic, homeostatic, surgical, and technical factors can cause a change in MEPs. The authors describe a case in which a bolus of magnesium sulfate resulted in a loss of amplitude of MEPs. Responses returned to near baseline about 20 minutes later. The patient did not have any new postoperative deficits. When MEP changes occur, in addition to evaluating other causes, magnesium sulfate administration should be considered.

KEY WORDS:

• Magnesium sulfate
• motor evoked potentials
• neurophysiologic intraoperative monitoring