UROLOGICAL ONCOLOGY Comparison of Classic and Inguinal Obturator Nerve Blocks Applied for Preventing Adductor Muscle Contractions in Bladder Tumor Surgeries: A Prospective Randomized Trial Recai Dagli1*, Mumtaz Dadali2, Levent Emir2, Sahin Bagbanci2, Hakan Ates3 Purpose: Obturator nerve block (ONB) has been performed in surgeries of transurethral resection of bladder tum- ors (TUR-BT) for the prevention of the development of obturator muscle contraction. Currently, classic and ingui- nal approaches are frequently being used. In the present study, we aimed to compare the success rate, performance speed, and complication risks of both approaches. Materials and Methods: Sixty-six patients who underwent TUR-BT under spinal anesthesia were randomly se- lected, and ONB was performed on the tumor location side using classic (n = 33) or inguinal (n = 33) approaches. Ten milliliters of 0.25% bupivacaine were administered using a peripheral nerve stimulator in both approaches. Two endpoints were defined in the study: Primary endpoint; the duration of the determination of the obturator nerve and number of interventions when each participant is assessed in at the end of the ONB procedure. Second- ary endpoint; development of contractions, and complications each participant is assessed during the TUR-BT and 24 hours after ONB. (Clinical Trial Registration Number: ACTRN12617001050347) Result: General anesthesia was applied to the five patients in the classic ONB group who detected diffuse or bilat- eral tumors. These patients were excluded from the study. Contractions developed in 4 patients in each group, no statistically significant difference was detected between the groups (14.3%, n = 4 versus 12.1%, n = 4) (P = 1.00). No complications were detected in both groups during the TUR-BT and 24 hours after ONB. We found that the inguinal approach provided a statistically significant advantage regarding the number of punctures (1.9 ± 0.9 ver- sus 1.5 ± 0.7) (P = .036), and duration of the procedure (99.1 ± 48.4 seconds versus 76.0 ± 31.9 seconds) (P=.029) compared with the classic approach. Conclusion: Although complications and success rates were similar in both groups, the inguinal method may be a better approach because it is faster and requires fewer punctures. Keywords: Obturator nerve block; transurethral resection of bladder tumor; bladder tumor; adductor spasm; nerve stimulator INTRODUCTION Transurethral resection of bladder tumors (TUR-BT) are frequently performed under spinal anesthesia, and contractions may develop in adductor muscles due to electrical stimuli applied during side wall localized tumor resection. As a consequence, bladder wall perfo- rations and pelvic organ injuries may develop. General anesthesia or obturator nerve block (ONB) may be re- quired so as to perform the required resection(1,2). Some studies showed that a safer surgical area could be pro- vided with ONB applied during TUR-BT, and tumor recurrence decreased because the required resection was performed(3). Different methods have been tested for preventing adductor muscle contractions during TUR-BT sur- geries(4-6). Some studies suggested that ONB could be performed through blind attempts using anatomic land marks and that it was a safe procedure(7,8). However, 1Department of Anesthesiology and Reanimation, Ahi Evran University Faculty of Medicine, Kirsehir, Turkey. 2Department of Urology, Ahi Evran University Faculty of Medicine, Kirsehir, Turkey. 3Department of Anesthesiology and Reanimation, Ahi Evran University Training and Research Hospital, Kirsehir, Turkey. *Correspondence: Department of Anesthesiology and Reanimation, Ahi Evran University Faculty of Medicine, Kirsehir 40200, Turkey. Tel: +905426536975. E-mail: drresel@gmail.com. Received September 2017 & Accepted April 2018 some studies reported complications due to block dur- ing the proceedings(9). Therefore, new approaches or nerve stimulator and ultrasonography have been used to provide a safer and effective block(10,11). At present, classic and inguinal approaches are used for ONB(10). The obturator nerve stems from the anterior division of the ventral rami of L2-L3-L4 nerves in the lumbar plex- us, contains motor and sensory nerve fibers. The nerve descends through the psoas major muscle. It runs close the inferolateral bladder, bladder neck, and prostatic urethra, along with the inner lateral wall of the pelvis. And then it enters the upper part of the obturator foramen and the thigh. The obturator nerve divides into anterior and posterior branches in the pelvic cavity, the obturator canal, or the thigh. The branches of obturator nerve emerges from the obturator foramen and runs among the pectineus and obturator externus muscles. The anterior branch Urological Oncology 62 Vol 16 No 01 January-February 2019 63 runs between the pectineus and adductor brevis mus- cles, as the posterior branch runs between the adductor brevis and adductor magnus muscles(12,13). The obtura- tor nerve is blocked from the obturator foramen in the classic method, and between the Adductor Brevis and Adductor Magnus muscles in the inguinal method(10). In literature, there are a numerous studies have been used with different methods, drugs, and devices for ONB. However, during the literature reviews, we have found that there are only a small number of studies on ONB application during TUR-BT with the current CONSORT guidelines. For this reason, we planned this parallel-group randomized clinical trial with current guidelines. In the present study, we aimed to compare the success rate, performance speed, and complication risks of both classic and inguinal ONB performance. MATERIALS AND METHODS Study population The patients who underwent TUR-BT due to bladder tumor in the Urology Clinic of Ahi Evran University Education and Training Hospital, and required ONB due to obturator muscle spasm were included in the study. The patients were informed about the study and written informed consents were obtained after the ap- proval of the Clinical Research Ethics Committee of Turgut Ozal University Faculty of Medicine (Decision No: 99950669/104) was given. (Clinical Trial Regis- tration Number: ACTRN12617001050347) Inclusion and exclusion criteria Patients who were American Society of Anesthesiol- ogists (ASA) risk grade I-III and aged between 18-80 years were included in the study. Patients who had un- dergone previous surgery in the study region and had anatomic disorders, neurologic problems such as par- estesia, muscle disease such as the motor neuron disor- ders and muscular atrophy, and coagulation disorders were excluded. Study design This study was a prospective, double blind, parallel group, randomize clinical trial. The patients who underwent cystoscopy under local anesthesia and had tumors on the side wall of the blad- der were examined preoperatively. Sixty-six patients who matching inclusion criteria and allowed ONB to practice were included in the study within the research period allowed by the Ethics Committee(01.02. 2016- 01.08.2017). Patients were randomized for classic (n = 33) and in- guinal (n = 33) ONBs by the principal investigator of the study (Figure 1). Simple randomization was done before study commencement by the Excel (Microsoft, Redmond, WA, USA) random number generation func- tion. Sixty-six patients included in the study were enu- merated as classical(1) and inguinal(2) and assigned to ONB 'groups and the procedures was carried out. Two endpoints were defined in the study: Primary end- point; the duration of the determination of the obturator nerve and number of interventions when each partic- ipant is assessed in at the end of the ONB procedure. Secondary endpoint; development of contractions, and complications each participant is assessed during the TUR-BT and 24 hours after ONB. Procedures Age, sex, body mass index (BMI), and ASA scores were recorded. Before surgery, 500 mL intravenous 0.9% NaCl was administered to the patients. Heart rate, SpO2, blood pressure, and electrocardiography were monitored in the operating room. Spinal anesthesia was performed using 12.5 mg hyperbaric bupivacaine after insertion of a 25-gauge Quincke spinal needle from L3-4 or L4-5 in the sitting position. Patients were laid in the supine position. Development of sensory block was examined at the T10 level. Required anatomic markings were made on the wall where the tumor was located by the approach to be ap- plied (Figure 2): In the classic method, the puncture point was marked 1.5 cm lateral of tuberculum pubis and 1.5 cm caudal. In the inguinal method, the tuberculum pubis, spina iliaca anterior superior, inguinal ligament, and femo- ral artery were marked. The puncture entry point was determined as the middle of the tuberculum pubis and Figure 1. CONSORT Flow Diagram of Study Figure 2. Obturator nerve block ((1) Spina iliaca anterior superior (2) Nervus obturatorius (3) Inguinal ligament (4) Tuberculum pu- bicus (5) Arteria femoralis (6) Classical approach ONB point (7) Inguinal approach ONB point) Obturator nerve blocks for adductor muscle contractions -Dagli et al. femoral artery, and 5-8 cm below the inguinal ligament. The required sterilization was applied on the surgical area. The patients were considered blind because of not seeing the surgical site during ONB administration and TUR-MT. The peripheral nerve stimulator (Pajunk, Melsungen, Germany) was adjusted to 1.5 mA 1 Hz. Insertion was applied from the determined points using an isolated 22-gauge, 100-mm nerve stimulator needle (Pajunk, Melsungen, Germany). The needle was directed ceph- alad in the inguinal approach. In the classic method, the needle was perpendicularly inserted and slightly withdrawn after reaching the bone; the needle was ma- nipulated 2-4 cm towards the medial. First, suction was performed, and then 10 mL 0.25% bupivacaine were administered when an adductor muscle contraction area was detected with the peripheral nerve stimulator be- tween the range of 0.4-0.7 mA. Withdrawal and remanipulation of the needle was counted as one puncture. The period between the first puncture insertion and local anesthesia injection was re- corded as the practice period. The duration of the determination of the obturator nerve of classic or inguinal ONB approaches were compared by stopwatch timing of procedure by the research as- sistant. ONB was administered by the same anesthesiologists while the urologist was not in the operating room. Ad- ductor muscle contractions and complications such as bladder perforation that occurred during the resection were recorded by a urologist who was blinded to the ONB technique. Transurethral resection of bladder tu- mor (TUR-BT) was performed using a 26-French bipo- lar resectoscope, and a 30-degree optic. We used 0.9% NaCI for irrigation. Surgery was initiated 10 minutes after the ONB. All ONB and TUR-BT procedures were performed by the same anesthesiologists and urologists. No other additional technique was performed for the prevention of adductor muscle contractions. The ONB applied zone was evaluated by the phisical examination 24 hours after the surgery. The complica- tions such as vein injuries, hematoma, paresthesia and motor neuronal deficit recorded by a urologist who was blinded to the ONB technique. Age, sex, BMI, ASA classification, success rates, punc- ture periods, complications, and switch rates to general anesthesia were compared between the two groups. Statistical Analysis The Statistical Package for the Social Sciences (SPSS) 23.0 (IBM SPSS Inc., Chicago, IL, USA) was used in data analysis. The Chi-square test was used in the comparison of qualitative data in addition to descrip- tive statistical methods (frequency, percentage, mean, standard deviation). The Kolmogorov-Smirnov and Shapiro-Wilk tests were used in the evaluation of nor- mally distributed data. The independent samples t-test was used to evaluate normally distributed quantitative data, and the Mann-Whitney U test was used in the evaluation of data with no normal distribution. Cor- relations of variables were evaluated using Pearson’s correlation tests. Probability values less than (P) α=.05 were regarded as significant and indicating a difference between the groups. Power analysis was performed the G*Power 3.1.9.2 Statistical Package Program; and power (1-β) was found as 0.86 considering n1 = 28, n2 = 33, α = .05, and effect size as d = .8. RESULTS General anesthesia was applied to the five patients in the classic ONB group who detected diffuse or bilateral tumors. These patients were excluded from the study. The demographic data are shown in Table 1. No sta- tistically significant difference was detected between the groups regarding sex, age, weight, height, BMI, and ASA scores (P = .091, P = .519, P = .907, P = .191, P = .494, P = .087). Although no statistically significant differences were detected regarding the development of adductor muscle contraction (P = 1.00), a statistically significant differ- ence was detected between the number of punctures (P = .036), and duration of the procedure (P = .029). The number of punctures was higher and duration of the Table 1. Comparison of the demographic characteristics between the groups Classic (n=28) Inguinal (n=33) P-value Sex Male 25 (89.3%) 33 (100.0%) .091* Female 3 (10.7%) 0 (0.0%) Age (Year) 61.0 ± 14.0 58.6 ± 15.1 .519** Weight(kg) 80.9 ± 13.8 81.3 ± 13.8 .907** Height (cm) 173.1 ± 8.5 170.7 ± 4.4 .191** BMI(kg/m2) 27.1 ± 5.0 28.0 ± 5.2 .494** ASA I 6 (21.4%) 9 (27.3%) .087*** II 16 (57.1%) 24 (72.7%) III 6 (21.4%) 0 (0.0%) * Chi-Square Test, ** Independent Samples t Test, *** Mann-Whitney U Classic (n=28) Inguinal (n=33) P- value Number of punctures 1.9 ± 0.9 1.5 ± 0.7 .036* Duration of the procedure (seconds) 99.1 ± 48.4 76.0 ± 31.9 .029* Contraction No 24 (85.7%) 29 (87.9%) 1.000** Yes 4 (14.3%) 4 (12.1%) * Independent Samples t Test, ** Chi-Square Test Table 2. Comparison of the groups regarding puncture-duration and procedure-development of adductor muscle contractions Obturator nerve blocks for adductor muscle contractions -Dagli et al. Urological Oncology 64 Vol 16 No 01 January-February 2019 65 procedure was longer in the classic ONB group (Table 2). No complications such as vein injuries, hematoma, paresthesia and motor neuronal deficit were detected in both groups during the TUR-BT and 24 hours after ONB. DISCUSSION Obturator nerve block has been used for anesthesia or postoperative analgesia in knee surgeries, in the treat- ment of adductor spasticity, and in the prevention of adductor muscle contractions during TUR-BT surgeries as a part of “3-in-1” blocks(14). The obturator nerve can be blocked from different anatomic regions during its navigation in the body(15). Block success rates vary de- pending on anatomic variations in the coursing of the obturator nerve(13). Therefore, different approaches or different equipment such as nerve stimulators and ultra- sonography have been tested to enable safer and more effective blocks(15). In their comparison study with 30 patients, Moningi et al. reported that inguinal approach was a good alterna- tive for the classic approach. Although vascular trau- ma was detected in 4 patients in the classic group, the researchers concluded that both approaches were simi- lar regarding the convenience of the practice(16). Even though no complications and no statistical differences were detected regarding success rates in our study, we found that the inguinal approach could be performed faster and with fewer punctures. Another study compared the classic and inguinal pubic approaches in 102 patients. The success rate (96.1% vs. 84%) was found higher, and fewer punctures were re- quired in the inguinal group, and the authors reported that the inguinal technique was anatomically easier to perform. Two failed blocks in the inguinal group, and eight failed blocks in the classic group were detected, with no complications in either group (17). In our study, although the success rate was higher in the inguinal group, no statistical significance was detected between the groups. We found that ONB could be performed faster with fewer punctures in the inguinal approach. Minimal contractions developed in four patients in each group, but they were not so intense as to prevent the surgical procedure or require switching to general an- esthesia. In another study, researchers found an 86% success rate and fewer complications with the classic approach us- ing a nerve stimulator for ONB(18). We also found simi- lar success rates in the classic approach. The success rate was reported as 90.5% using a nerve stimulator in the inguinal group in a study by Hızlı et al. In their study, the block could not be provided in 2 pa- tients out of 21 in the inguinal group under ultrasonog- raphy. Bladder perforation developed in two patients (19). Different to that study, we used a nerve stimulator only, and the success rate was found as 87.9%. Despite the fact that complete block could not be accomplished in four patients, no complications were detected. Sharma et al. conducted a study using a nerve stimula- tor on 20 patients in the classic approach. A minimal contraction was observed in one patient, and complete block was accomplished in the other patients(20). How- ever, a mixture of 15 mL lignocaine and bupivacaine was used in that study. We used 10mL 0.25% bupiv- acaine in our study. A higher success rate was detected in that study compared with ours. The high success rate could be due to the use of high-volume, high-concen- tration drugs. Different methods, different drugs, and different drug concentrations were used in ONB studies, and very dif- ferent success rates were obtained(2,21,22). Higher success rates were obtained in some blind attempt ONB studies (7). On the other hand, less local anesthetic drugs were used in studies where both nerve stimulator and ultra- sonography were used to avoid systemic local anesthet- ic drug toxicity compared with blind attempt blocks (11,22). Bolat et al. used 0.25% levobupivacaine in their study and found the success rate as 88.6%, which was similar to ours(18). Limitations: Only sixty-six patients who matching in- clusion criteria could be included in the study within the research period allowed by the Ethics Committee, and thus the power analysis of study was performed. The drug was administered into the first detected re- gion using a nerve stimulator between 0.4-0.7 mA in both approaches in our study. No other intervention was performed to identify other branches of the obturator nerve. We suggest that this was one of the reasons we had more contractions in our study. The depth of the stimulator needle at the injection site may affect the administration speed. We did not investigate the depth in our study because the needles were manipulated at different angles after penetration into the skin in both methods. Some studies found a higher depth in the in- guinal approach, but they did not compare the block performance speed(17). We suggest that more punctures were required in classic approach ONB because the ob- turator nerve was located deeper during the navigation from the obturator foramen; therefore, it was more dif- ficult to determine the location. CONCLUSIONS In conclusion, although the complication and success rates were similar in both methods, it seems that the inguinal method with a nerve stimulator is a better ap- proach because it enables faster ONB with fewer punc- tures. CONFLICT OF INTEREST The authors report no conflict of interest. REFERENCES 1. Kitamura T, Mori Y, Ohno N, Suzuki Y, Yamada Y. [Case of bladder perforation due to the obturator nerve reflex during transurethral resection (TUR) of bladder tumor using the TUR in saline (Turis) system under spinal anesthesia]. Masui. 2010;59:386-9. 2. Hradec E, Soukup F, Novak J, Bures E. The obturator nerve block. Preventing damage of the bladder wall during transurethral surgery. Int Urol Nephrol. 1983;15:149-53. 3. Erbay G, Akyol F, Karabakan M, Celebi B, Keskin E, Hirik E. Effect of obturator nerve block during transurethral resection of lateral bladder wall tumors on the presence of detrusor muscle in tumor specimens and recurrence of the disease. Kaohsiung J Med Sci. 2017;33:86-90. 4. Augspurger RR, Donohue RE. Prevention Obturator nerve blocks for adductor muscle contractions -Dagli et al. of obturator nerve stimulation during transurethral surgery. J Urol. 1980;123:170-2. 5. Ong EL, Chan ST. Transurethral surgery and the adductor spasm. Ann Acad Med Singapore. 2000;29:259-62. 6. Ozer K, Horsanali MO, Gorgel SN, Ozbek E. Bladder injury secondary to obturator reflex is more common with plasmakinetic transurethral resection than monopolar transurethral resection of bladder cancer. Cent European J Urol. 2015;68:284-8. 7. Khorrami M, Hadi M, Javid A, et al. A comparison between blind and nerve stimulation guided obturator nerve block in transurethral resection of bladder tumor. J Endourol. 2012;26:1319-22. 8. Tatlisen A, Sofikerim M. Obturator nerve block and transurethral surgery for bladder cancer. Minerva Urol Nefrol. 2007;59:137-41. 9. Akata T, Murakami J, Yoshinaga A. Life- threatening haemorrhage following obturator artery injury during transurethral bladder surgery: a sequel of an unsuccessful obturator nerve block. Acta Anaesthesiol Scand. 1999;43:784-8. 10. Choquet O, Capdevila X, Bennourine K, Feugeas JL, Bringuier-Branchereau S, Manelli JC. A new inguinal approach for the obturator nerve block: anatomical and randomized clinical studies. Anesthesiology. 2005;103:1238-45. 11. Manassero A, Bossolasco M, Ugues S, Palmisano S, De Bonis U, Coletta G. Ultrasound-guided obturator nerve block: interfascial injection versus a neurostimulation- assisted technique. Reg Anesth Pain Med. 2012;37:67-71. 12. Jo SY, Chang JC, Bae HG, Oh JS, Heo J, Hwang JC. A Morphometric Study of the Obturator Nerve around the Obturator Foramen. J Korean Neurosurg Soc. 2016;59:282-6. 13. Selmi NH, Sahin S, Gurbet A, et al. Obturator Nerve Block in Adductor Spasticity: Comparison of Peripheral Nerve Stimulator and Ultrasonography Techniques. Turk J Anaesth Reanim. 2013;41:121. 14. Yoshida T, Nakamoto T, Kamibayashi T. Ultrasound-Guided Obturator Nerve Block: A Focused Review on Anatomy and Updated Techniques. Biomed Res Int. 2017;2017:7023750. 15. Anagnostopoulou S, Kostopanagiotou G, Paraskeuopoulos T, Chantzi C, Lolis E, Saranteas T. Anatomic variations of the obturator nerve in the inguinal region: implications in conventional and ultrasound regional anesthesia techniques. Reg Anesth Pain Med. 2009;34:33-9. 16. Moningi S, Durga P, Ramachandran G, Murthy PV, Chilumala RR. Comparison of inguinal versus classic approach for obturator nerve block in patients undergoing transurethral Obturator nerve blocks for adductor muscle contractions -Dagli et al. resection of bladder tumors under spinal anesthesia. J Anaesthesiol Clin Pharmacol. 2014;30:41-5. 17. Jo YY, Choi E, Kil HK. Comparison of the success rate of inguinal approach with classical pubic approach for obturator nerve block in patients undergoing TURB. Korean J Anesthesiol. 2011;61:143-7. 18. Bolat D, Aydogdu O, Tekgul ZT, et al. Impact of nerve stimulator-guided obturator nerve block on the short-term outcomes and complications of transurethral resection of bladder tumour: A prospective randomized controlled study. Can Urol Assoc J. 2015;9:E780-4. 19. Hizli F, Argun G, Guney I, et al. Obturator nerve block transurethral surgery for bladder cancer: comparison of inguinal and intravesical approaches: prospective randomized trial. Ir J Med Sci. 2016;185:555-60. 20. Sharma D, Singh VP, Agarwal N, Malhotra MK. Obturator Nerve Block in Transurethral Resection of Bladder Tumor: A Comparative Study by two Techniques. Anesth Essays Res. 2017;11:101-4. 21. Kakinohana M, Taira Y, Saitoh T, Hasegawa A, Gakiya M, Sugahara K. Interadductor approach to obturator nerve block for transurethral resection procedure: comparison with traditional approach. J Anesth. 2002;16:123-6. 22. Pladzyk K, Jureczko L, Lazowski T. Over 500 obturator nerve blocks in the lithotomy position during transurethral resection of bladder tumor. Cent European J Urol. 2012;65:67-70. Urological Oncology 66