Surgical Causes of Significant Intraoperative Neuromonitoring Signal Changes in Three-Column Spinal Surgery

Abstract

Study Design: Retrospective case series.Purpose: To evaluate the risks and causes of neurologic complications in three-column spinal surgery by analyzing intraoperativeneurophysiological monitoring (IONM) data.Overview of Literature: Three-column spinal surgery, which may be required to correct complex spinal deformities or resection ofspinal tumors, is known to carry a high risk of neurologic complications. However, few studies reported a specific surgical procedurerelated to a significant IONM signal change during surgery.Methods: Multimodality IONM data, including somatosensory-evoked potentials (SSEP) and motor-evoked potentials (MEP), werereviewed in 64 patients who underwent three-column spinal surgery from 2011 to 2015. Surgical procedures included posterior vertebralcolumn resection, pedicle subtraction osteotomy, total en bloc spondylectomy, piecemeal spondylectomy, and corpectomy withlaminectomy (n=27) in three cervical, 34 thoracic, and 31 lumbar procedures.Results: Significant IONM signal changes occurred in 11 of 64 (17.1%) patients. SSEP and MEP were changed in 11 patients. Postoperativeneurologic deterioration occurred in 54.5% (6 of 11) of the patients, and two of them were permanent. There was no postoperativeneurologic deterioration in patients without significant signal change. Suspected causes of IONM data changes are as follows:adhesion/tethering, translation, contusion, and perfusion.Conclusions: Based on the results of this study, to enhance neurologic safety in three-column spinal surgery, surgeons should payattention to protect the spinal cord from mechanical insult, especially when the spinal column was totally destabilized during surgery,and not to compromise perfusion to the spinal cord in close cooperation with a neurologist and anesthesiologist