Intraoperative neurophysiologic monitoring: utility and anesthetic implications

Intraoperative neurophysiologic monitoring (IONM) has been rapidly adopted as a standard monitoring technique for a growing number of surgical procedures. This article offers a basic review of IONM and discusses some of its latest applications and anesthetic techniques that optimize monitoring conditions.

IONM has been demonstrated to alert the surgical team to potential injury and can also be used to detect impending positioning injuries. Upper extremity somatosensory evoked potential monitoring is particularly helpful in preventing ulnar neuropathy that is more common in patients who are positioned prone and with severe arm abduction. Somatosensory evoked potential monitoring has a high specificity for vascular compromise and neurologic ischemia that may occur during neurovascular procedures. Electroencephalography is also helpful in alerting the surgical and anesthesia teams to an impending ischemic event. Although a total intravenous anesthesia technique offers better monitoring conditions, propofol may prolong emergence.

IONM is commonly used in a growing number and variety of surgical procedures, and has been shown to improve outcomes. IONM poses challenges for the anesthesiologist, but tailoring the anesthetic to be compatible with the monitoring techniques in use can help to prevent surgical complications.