Hemodynamic Neuromonitoring, a Proposed Spino-Cardiac Protective Reflex: Prospective Study in 200 Patients of Lumbar Surgery

Abstract

Background: Parasympathomimetic reflexes are reported in literature in spine surgery. Our primary hypothesis is proposed that nociceptive stimuli can be elicited by various maneuvers of lumbar spinal surgery and the physiological manifestation depends on many patient variables and anesthesia. However, a sympathomimetic pathological response is indicative of potential neural damages, which may or may not be reversible. A spino-cardiac protective reflex (SPR), as a new entity for lumbar spinal surgery, is proposed. Study Design: This was a prospective single institution. Materials and Methods: All the patients who were undergoing single motion segment transforaminal lumbar interbody fusion (TLIF) in our institute for lumbar disc herniation or non-discogenic lumbar stenosis lumbar spinal stenosis were included who fitted into inclusion criteria till 200 subjects were recruited. Patients’ pertinent vital data were collected at clinical first pre-operative visit and preoperatively on admission. The intraoperative parameters were recorded: Pre-induction, post-induction, post-positioning, before skin incision, after skin/subcutaneous exposure, pre-screw insertion, after screw insertion, after rod connection and distraction, during central decompression-laminotomy/laminectomy, during lateral recess decompression, discectomy, and segmental compression. Significant pulse rate (PR) and mean arterial pressure (MAP) changes were monitored and correlated. Results: In the enrolled 200 patients, the change in mean MAP and PR changes in varying steps of TLIF was not significant. The positivity of a significant change in MAP and PR correlating with an evident manipulative/pathological-demographic cause was noted (plausibility), which could revert back to baseline (reversibility) after addressing the culprit in 22 cases. Non-correlating raise was also noted in 35 cases. Conclusion: Spino-protective reflex exists like any reflex in body. Prospective study on huge database needs to be done to validate these observations. However, this study does make the surgeon think for finding clues to neurological damage or left out residual compressions which can be identified and rectified in real time in many cases. INOM is the standard of care and SPR should be compared with intraoperative neuromonitoring to identify sensitivity and threshold of pathological response in future studies. Keywords: Lumbar, Protective, Reflex, Spine, Sympathomimetic, Transforaminal lumbar interbody fusion