Intraoperative Neuromonitoring in Pediatric and Adult Spine Deformity Surgery

Study Design: Review of techniques and description of institutional clinical experience. Objective: To provide a historical review and description of key neuromonitoring concepts, focusing on neurogenic motor-evoked potentials and descending neurogenic evoked potentials, and to review the authors' experience with neuromonitoring techniques in children and adults undergoing spinal deformity surgery. Summary of Background Data: The original form of neuromonitoring, the Stagnara wake-up test, remains the "gold standard" for detecting true neurological deficits. Multiple newer modalities involving cortical and muscular monitoring, such as somatosensory evoked potentials and motor evoked potentials, have been developed and are widely used. Descending and neurogenic evoked potentials are becoming more common for neuromonitoring in patients undergoing spinal deformity surgery. Methods: A PubMed search for literature related to "neuromonitoring" was performed, and recent, as well as historical, articles were reviewed. Clinical experience regarding the use of neuromonitoring in adult and pediatric spinal deformity surgery was obtained from institutional experts. Results: Although not regularly used, the Stagnara wake-up test remains the gold standard for detecting neurological injury. Somatosensory evoked potentials measure signals transmitted from the periphery to the cortex and have historically been widely used but are limited by delay, poor localization, and the inability to detect damage to motor tracts. Motor evoked potentials continue to be used widely and measure muscular activity after cortical stimulation, but they are difficult to interpret in patients with underlying motor disorders and cannot be continuously monitored. Newer techniques such as descending neurogenic evoked potentials and neurogenic motor evoked potentials monitoring are used at some high-volume centers. Conclusions: Familiarity with the history of neuromonitoring in spinal deformity surgery and an understanding of the physiological systems used for neuromonitoring provide a framework from which spine surgeons can select appropriate monitoring for their patients.