Evolving Indications for Neuromonitoring In Spinal Surgery: What and When to Monitor

ABSTRACT Intraoperative neuromonitoring (IONM) is utilized during spine surgery to help prevent intraoperative neurologic injury. The first reported use of IONM in humans occurred more than four decades ago. Since its initial inception, technological advances such as the ability to monitor afferent sensory pathways and efferent motor pathways has greatly improved the efficiency and accuracy of IONM. Clinical research has established the superiority of multimodal IONM over unimodal techniques. However, controversy still exists regarding the most appropriate use of IONM. Currently, the surgeon is responsible for the interpretation of neuromonitoring alerts with the assistance of technicians and neurologists. Furthermore, the surgeon must determine the interventions necessary to mitigate neurologic risk according to such alerts. To that end, this chapter provides a historical context for IONM, reviews the physiologic mechanisms of common IONM modalities and examines the clinical evidence for IONM use.