Comparison of Adductor Muscle Spasm During Transurethral Resection of Bladder Tumor with Ultrasound-Guided Obturator Nerve Block Under Spinal Versus General Anesthesia: A Randomized Clinical Trial

Abstract

Background: Adductor muscle spasm during transurethral resection of bladder tumors (TURBT) can compromise surgical conditions and increase the risk of complications. Obturator nerve block (ONB) is used to reduce obturator-related adductor spasm, particularly during spinal anesthesia. However, the comparative effectiveness of spinal versus general anesthesia when combined with ONB remains uncertain. Objectives: To compare the incidence and severity of adductor muscle spasm during TURBT between spinal anesthesia and general anesthesia, when both techniques are combined with ultrasound-guided ONB. Methods: In this open-label randomized clinical trial, 70 patients scheduled for TURBT were randomly assigned to spinal anesthesia (SA+ONB; 12.5 mg hyperbaric bupivacaine) or general anesthesia (GA+ONB; fentanyl and propofol without neuromuscular blockade). All patients received ultrasound-guided ONB with 10 mL of 1.5% lidocaine. The primary outcome was the incidence and severity of adductor muscle spasm. Secondary outcomes included intraoperative heart rate, mean arterial pressure, duration of surgery, and surgeon satisfaction. Results: Adductor muscle spasm occurred in 2/35 patients (5.7%) in the SA+ONB group and 3/35 (8.6%) in the GA+ONB group. The risk difference was −2.9 percentage points (95% CI, −15.3 to 9.6), and the risk ratio was 0.67 (95% CI, 0.12 - 3.75); Fisher’s exact test showed no significant difference (P = 1.00). No severe spasms occurred. Excellent surgeon satisfaction was reported for 33/35 (94.3%) and 32/35 (91.4%) patients in the SA+ONB and GA+ONB groups, respectively (P = 0.81). The mean surgical duration was 80.17 ± 23.55 vs 77.97 ± 19.52 minutes (P = 0.67). The mean intraoperative heart rate was 67.26 ± 12.22 vs 69.20 ± 11.53 beats/min (P = 0.496), and the mean arterial pressure was 86.54 ± 10.68 vs 87.17 ± 12.20 mm Hg (P = 0.819). Conclusions: Among patients undergoing TURBT with ultrasound-guided ONB, adductor muscle spasm occurred infrequently, with no statistically significant difference between spinal and general anesthesia. However, these findings do not establish equivalence between the two techniques or the independent efficacy of ONB, given the absence of a non-ONB control group and the small number of spasm events.