Posterior quadratus lumborum block or lumbar erector spinae plane block for postoperative analgesia management after lumbar spinal surgery: a randomized controlled trial

PURPOSE: Postoperative pain after lumbar microdiscectomy (MD) can be significant. While both the lumbar erector spinae plane block (L-ESPB) and the posterior quadratus lumborum block (P-QLB) are used for analgesia, they have not been directly compared. We hypothesized that L-ESPB and P-QLB would provide different levels of analgesia after MD. METHODS: This single-center, prospective, randomized controlled trial included 60 adult patients (ASA I-II) undergoing unilateral single-level lumbar MD. Patients were randomized to receive a bilateral, postoperative L-ESPB (n = 30) or P-QLB (n = 30) with 30 mL of 0.25% bupivacaine per side. The primary outcome was the Numerical Rating Scale (NRS) pain score at 2 h postoperatively. Secondary outcomes included NRS pain scores over 24 h, rescue analgesia requirements, and adverse events. RESULTS: Patients in the L-ESPB group had statistically lower static and dynamic NRS pain scores at all measured time points (1, 2, 4, 8, 16, and 24 h) compared to the P-QLB group (p = 0.001). The number of patients requiring rescue analgesia was lower in the L-ESPB group (1 vs. 9 patients, p = 0.012), and the total tramadol consumption was also lower (p = 0.005). The incidence of nausea and itching was significantly lower in the L-ESPB group. One patient in the L-ESPB group experienced a temporary motor block. CONCLUSION: In patients undergoing lumbar MD, L-ESPB provided superior analgesia and resulted in lower opioid consumption and fewer opioid-related side effects compared to P-QLB over the first 24 postoperative hours.