Modified Thoracolumbar Interfascial Plane Versus Erector Spinae Plane Block for Postoperative Analgesia After Lumbar Discectomy: A Prospective Observational Comparative Study

Background: Effective pain control after lumbar disc surgery is a key determinant of recovery. Therefore, we aimed to compare the effects of modified thoracolumbar interfascial plane block (M-TLIP) and erector spinae plane block (ESP) on postoperative pain control and opioid consumption. Methods: This prospective observational comparative cohort study included 96 patients aged 18–70 years with American Society of Anesthesiologists (ASA) physical status I–III who underwent elective single-level lumbar discectomy. Patients received either an M-TLIP block (Group M-TLIP, n = 49) or an ESP block (Group ESP, n = 47). Postoperative pain was assessed using visual analog scale (VAS) scores at 1, 2, 4, 8, and 24 h as the primary outcome. Secondary outcomes included opioid consumption, postoperative nausea and vomiting, Riker’s Agitation Sedation Scale (RSAS) scores, and patient satisfaction. Repeated pain measurements were analyzed using a linear mixed-effects model. Results: Postoperative pain scores were lower in the M-TLIP group compared with the ESP group, particularly during the early postoperative period. Linear mixed-effects modeling demonstrated a significant main effect of group and time, with the analgesic advantage of M-TLIP being most pronounced in the early postoperative hours and diminishing by 24 h. Total tramadol consumption within the first 24 h was significantly lower in the M-TLIP group (p = 0.039). Postoperative agitation, nausea and vomiting, and patient satisfaction scores were comparable between groups. Conclusions: These findings suggest that M-TLIP block may represent a clinically useful alternative to ESP block for postoperative analgesia in lumbar discectomy.