I think let's move on with the session. The next talk is Dr. Reed, Utility of Neuromonitoring During Lumbar Pedicle Subtraction Osteotomy for Adult Deformity. Thank you. Rigid, inflexible deformities present a greater challenge in adult deformity surgery, frequently requiring bony cuts, osteotomies involving the anterior column, such as pedicle subtraction osteotomies or vertebral column resections. These osteotomies increase the risks of these surgeries with major complication rates around 35%, significantly increased blood loss, as well as an increased risk of both spinal cord injury and nerve root compression, particularly at the osteotomy site. Intraoperative neuromonitoring is a tool that's frequently used and been shown to prevent neurological injury in the cervical and thoracic spine by offering intraoperative real-time information about potential ongoing or impending neurologic injury. It allows surgeons to potentially correct or reverse any actions that they may have done to cause nerve injury. This has been widely used and demonstrated to be useful in pediatric spinal deformity patients with a sensitivity and specificity north of 80%. The false positive rate, however, in adults is significantly higher, possibly due to changes in spinal cord physiology, as well as a different nature of these diseases, pediatric deformity being a higher percentage of thoracic or coronal problems, whereas adult deformity is largely lumbar and sagittal, as well as an increase in fixed deformity in the adult population. So these results from these pediatric studies may not be directly applicable to adult spinal deformity. The aim of our study was to evaluate the utility of MEPs when operating in adult fixed deformities, particularly in detecting neurological injury in patients undergoing a PSO. It was a retrospective single-surgeon cohort, all consecutive patients undergoing a PSO in between 2006 and 2016. All cases were reviewed by a blinded neurophysiologist. Our threshold for monitoring changes was a 50% or greater decrease in motor evoked potentials. These changes were then correlated with postoperative exams to evaluate their sensitivity, specificity, and predictive values. 242 total PSO cases of those single changes occurred in 38. 21 of those patients recovered completely. 17 had permanent changes. Of the 17 permanent changes, 9 had no recovery, 8 had a partial recovery. During the operation, changes occurred at a mean time of 8 or 9 minutes after the closure of the PSO, beginning with a range of immediately during closure or up to 55 minutes afterwards. The average signal loss was 72%. The overall complication rate in these patients was 25%. The rate of new neurologic post-op deficits was 4%. MEP signal changes was not associated significantly with complications for postoperative neurologic deficits in our study. An 80% signal loss as opposed to a 50% loss did correlate significantly with a higher rate of neurologic deficit. This table just shows the positive neuromonitoring changes as compared to the positive or postoperative neurologic changes. Of the 10 patients who had postoperative exam patients, only 3 were detected or correlated with neuromonitoring changes. Of the 38 patients who had neuromonitoring changes, only 3 of those had postoperative deficits with a positive predictive value of 8%, sensitivity of 30%, and a specificity of 85%. The limitations of this study, obviously its retrospective nature as well as the low incidence of neurologic deficit make it difficult to power the analysis. In conclusion, neurologic complication rate is low. Incidence of neuromonitoring changes is infrequent. A change threshold of 50% was not a predictor of complications or neurologic deficits. A reduction of 80% or greater in MEPs correlated significantly with higher odds of neurologic deficits. Overall, transcranial MEP monitoring is limited in its ability to reliably detect neurologic changes in patients undergoing lumbar PSL. Thanks very much. Thank you.

intraoperative neuromonitoring

lumbar pedicle subtraction osteotomy

adult deformity surgery

motor evoked potentials

neurological deficits