Comparing the Effect of Classical and Modified Thoracolumbar Interfascial Plane Block on Postoperative Pain and IL-6 Level in Posterior Lumbar Decompression and Stabilization Surgery

Background: Ultrasound (US)guided classical and modified thoracolumbar interfascial plane (TLIP) blocks are often used to provide adequate analgesia after lumbar spinal surgery. Postoperative proinflammatory interleukin 6 (IL6) blood concentrations after lumbar spine surgery are related to postoperative pain and inflammation. Objectives: The purpose of this prospective randomized parallel controlled study was to assess postoperative pain and serum levels of proinflammatory IL6 after posterior lumbar decompression and stabilization surgery with a classical and modified technique of TLIP block. Methods: This prospective randomized, singleblinded controlled pilot study was conducted on eight patients who will undergo posterior lumbar decompression and stabilization surgery. After obtaining the ethical approval and an informed consent, all subjects were randomly allocated into the classic TLIP group and the modified TLIP group. Following general anesthesia induction, 20 mL bupivacaine 0.25% was injected on each side in interfascialis plane between m. longissimus and m. iliocostalis in modified TLIP group and between m. multifidus and m. longissimus in classical TLIP group. Intraoperative hemodynamic (blood pressure and heart rate) and noxious stimulation response level (qNOX), postoperative IL6 level, 24hour morphine consumption, and numerical rating score were recorded and analyzed. Results: The median of IL6 level was found to be lower in the modified TLIP group 12 hours postoperatively compared to classic TLIP (29.91 (8.56 – 87.61) vs. 46.87 (2.87 – 92.35)). The mean Numerical Rating Scale (NRS) in the modified TLIP block was comparable with the classic TLIP group, although it was lower than the classic TLIP group (2.75 ± 1.5 vs. 3.75 ± 1.7 at 6 hours and 3.5 ± 1.3 vs. 4 ± 1.6 12 hours postoperatively). However, there was no difference in intraoperative hemodynamic, Qnox value, and total postoperative morphine consumption between the two groups. Conclusions: Our study showed that modified TLIP block resulted in lower IL6 level and NRS 12 hours postoperatively compared to classical TLIP block. However, there were no differences in total postoperative morphine consumption between the two groups.