As we enter the era of smart imaging, artificial intelligently designed augmented reality systems…is one of the oldest methods for ensuring an error-free surgery—neuromonitoring—as necessary as it used to be?
Led by the inestimable research team at Philadelphia’s Rothman Orthopaedics Institute, a group of researchers took a fresh look at neuromonitoring and powered their study with a huge, 27, 808, number of cases. The results of their work, “Linking Patterns of Intraoperative Neuromonitoring (IONM) Alerts to the Odds of a New Postoperative Neurological Deficit,” appears in the April 1, 2023, edition of Clinical Spine Surgery.
“Our team set out to examine patterns of neuromonitoring alerts and the risk of novel neurological deficits for patients diagnosed with myelopathy, stenosis, or radiculopathy,” co-author Alexander Vaccaro, M.D., Ph.D., M.B.A., president of Rothman Orthopaedics Institue, told OTW.
“We categorized alerts by patterns of modalities or nerves/muscles involved, and alert status upon surgical closure. For every procedure, we determined the baseline monitorability of motor evoked potentials from each muscle and the somatosensory evoked potentials from stimulation of each upper and lower extremity. Our team noted alerts for each modality and each involved muscle or nerve. The signal changes were noted as either ‘resolved’ or ‘unresolved’ at closure for each modality and muscle or nerve for which an alert was given.”
“We found a significantly increased risk of a new neurological deficit for posterior procedures vs anterior approaches, as well as procedures involving three levels compared with one,” commented Dr. Vaccaro to OTW.
“Compared with cases with no alerts, those with unresolved spinal cord alerts were associated with the greatest elevation in risk followed by unresolved C5-6 Nerve Root, C5-T1 Nerve Root/Arm, C7 Nerve Root, and C8-T1 Nerve Root alerts,” wrote the authors. “Significant reductions in risk were seen for resolved Spinal Cord, C5-6 Nerve Root, and C8-T1 nerve alerts. Overall, unresolved motor evoked potential and somatosensory evoked potential alerts were associated with the greatest elevation in risk (OR:340.92) followed by unresolved motor evoked potential-only and unresolved somatosensory evoked potential-Only alerts. These relationships were similar across diagnostic cohorts.”
Concerning differences by diagnosis, the team determined that patients with myelopathy were most likely to have a new-onset postop neurological deficit. Those with neurogenic stenosis were less likely to have a new neurological deficit and radiculopathy patients were least likely to have a new neurological deficit.
“This work shows us that the degree of risk elevation—as well as risk mitigation after an intraoperative neuromonitoring alert—is dependent on the type and pattern of alert,” said Dr. Vaccaro to OTW.
“While intraoperative neuromonitoring is not the standard of care, we think it provides critical information that can help surgeons intervene in a timely fashion when an alert occurs to adjust blood pressure in the setting of myelopathy or deformity correction, remove spinal instrumentation, or undo a corrective maneuver in a spinal deformity procedure, among other things. Additionally multimodal neuromonitoring may alert the surgeon to a potential impending issue due to positioning or compression at the level of the brachial plexus, elbow, wrist, or proximal tibia—and thus minimize the chances of a postoperative palsy.”
The data as explained here doesn’t answer the question as to the usefulness of monitoring. The data should be reviewed asking the questions—1.what % of monitored pts had correctable alerts? 2. What was the incidence of new neuro deficits compared to unmonitored controls? Otherwise, we may end up monitoring all cases for a tiny number of new deficits, and there may be a selection bias for those cases which have new deficits following unresolved alerts, suggesting that monitoring made no difference.
Worth pursuing further, I think.