121. Nerve root retraction time during lumbar endoscopic discectomy is associated with postoperative radiculitis

BACKGROUND CONTEXT Lumbar disc herniations are one of the most common spinal pathologies leading to low back pain and radiculopathy. The open lumbar discectomy was considered a gold standard; however, it involves general anesthesia, a large skin incision and substantial muscle retraction. Recent advancements in discectomy procedures include the use of full endoscopic techniques using the inter laminar and extraforaminal approaches. While endoscopy reduces tissue retraction and incision size, the procedures require scope placement within the foramen and lateral recess and substantial nerve root retraction. Nerve root retraction time has shown to correlate with neurologic complications in other lumbar surgical techniques. PURPOSE The aim of the current study was to evaluate the relationship between nerve root retraction time and postoperative radiculitis and other patient reported outcomes. STUDY DESIGN/SETTING Single center, retrospective analysis of prospectively collected data. PATIENT SAMPLE Patients undergoing lumbar endoscopic discectomy between 2020-2022. OUTCOME MEASURES Postoperative complications, pre- and postoperative PROs (VAS, ODI and CAT). METHODS The current study included patients who underwent single- or multilevel lumbar discectomy between 2020 and 2022 for lumbar disc herniations. Current study was IRB exempt. Demographic and intraoperative variables were recorded. Data on postoperative complications, pre- and postoperative PROs (VAS, ODI and CAT) were collected at various time points up to one year. Paired sample 2-tailed t-test and multivariate regression with p<0.05 being significant were utilized. RESULTS A total of 157 patients underwent single- or multilevel endoscopic lumbar discectomy between 2020 and 2022. 112 (71.3%) of the discectomies were single-level procedures, 44 (28.0%) were 2-level, and one (0.7%) was 3-level. In total, 43 (27.4%) were performed via an interlaminar approach, 5 (3.2%) were performed via a sublaminar approach, and 107 (68.2%) were performed via an extraforaminal approach. Average surgical time was 29.4 minutes and average estimated blood loss was 7.05mL. Average patient age was 44 years of age, and 64% were male patients. Nerve retraction time was between 4 and 15 minutes. Twenty-four patients (18%) reported a new neurological deficit - radiculitis at 2-weeks postoperatively. In patients with radiculitis 86% reported significantly worse VAS leg at 2 weeks postop (4.2 vs 8.3, p<0.001) compared to 14% who had improved VAS leg (9.3 vs 7, p=0.1181). Patients with radiculitis and worse VAS scores had substantially longer nerve retraction time (13.8±7.5 min) than patients with improved VAS leg (6.7±1.2 min). In radiculitis patients with longer nerve retraction time VAS leg remained higher than the preoperative values at later time points. At 6 months in patients with longer nerve retraction time there was no significant improvement in the ODI score (0.52 vs 0.46, p=0.306). Similar trends were observed for CAT domains for pain interference, pain intensity and physical function. CONCLUSIONS This is the largest study to our knowledge that has looked at the nerve root retraction time as a risk factor for radiculitis and diminished patient outcomes in the endoscopic discectomy literature. The initial findings show that patients with new onset radiculitis who had longer nerve retraction time have worse VAS leg outcomes at early and later time points, and minimal improvement in ODI and CAT scores. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. Lumbar disc herniations are one of the most common spinal pathologies leading to low back pain and radiculopathy. The open lumbar discectomy was considered a gold standard; however, it involves general anesthesia, a large skin incision and substantial muscle retraction. Recent advancements in discectomy procedures include the use of full endoscopic techniques using the inter laminar and extraforaminal approaches. While endoscopy reduces tissue retraction and incision size, the procedures require scope placement within the foramen and lateral recess and substantial nerve root retraction. Nerve root retraction time has shown to correlate with neurologic complications in other lumbar surgical techniques. The aim of the current study was to evaluate the relationship between nerve root retraction time and postoperative radiculitis and other patient reported outcomes. Single center, retrospective analysis of prospectively collected data. Patients undergoing lumbar endoscopic discectomy between 2020-2022. Postoperative complications, pre- and postoperative PROs (VAS, ODI and CAT). The current study included patients who underwent single- or multilevel lumbar discectomy between 2020 and 2022 for lumbar disc herniations. Current study was IRB exempt. Demographic and intraoperative variables were recorded. Data on postoperative complications, pre- and postoperative PROs (VAS, ODI and CAT) were collected at various time points up to one year. Paired sample 2-tailed t-test and multivariate regression with p<0.05 being significant were utilized. A total of 157 patients underwent single- or multilevel endoscopic lumbar discectomy between 2020 and 2022. 112 (71.3%) of the discectomies were single-level procedures, 44 (28.0%) were 2-level, and one (0.7%) was 3-level. In total, 43 (27.4%) were performed via an interlaminar approach, 5 (3.2%) were performed via a sublaminar approach, and 107 (68.2%) were performed via an extraforaminal approach. Average surgical time was 29.4 minutes and average estimated blood loss was 7.05mL. Average patient age was 44 years of age, and 64% were male patients. Nerve retraction time was between 4 and 15 minutes. Twenty-four patients (18%) reported a new neurological deficit - radiculitis at 2-weeks postoperatively. In patients with radiculitis 86% reported significantly worse VAS leg at 2 weeks postop (4.2 vs 8.3, p<0.001) compared to 14% who had improved VAS leg (9.3 vs 7, p=0.1181). Patients with radiculitis and worse VAS scores had substantially longer nerve retraction time (13.8±7.5 min) than patients with improved VAS leg (6.7±1.2 min). In radiculitis patients with longer nerve retraction time VAS leg remained higher than the preoperative values at later time points. At 6 months in patients with longer nerve retraction time there was no significant improvement in the ODI score (0.52 vs 0.46, p=0.306). Similar trends were observed for CAT domains for pain interference, pain intensity and physical function. This is the largest study to our knowledge that has looked at the nerve root retraction time as a risk factor for radiculitis and diminished patient outcomes in the endoscopic discectomy literature. The initial findings show that patients with new onset radiculitis who had longer nerve retraction time have worse VAS leg outcomes at early and later time points, and minimal improvement in ODI and CAT scores.