The obturator nerve block

During transurethral electroresection in the posterolateral bladder neck, trigone and posterior urethra, unintentional contractions of the thigh-adductor muscles may occur due to irritation of the obturator nerve. The sudden displacement of the bladder wall against the cutting loop may cause a perforation of the bladder. The authors describe the topographic relation of the bladder wall to the passage of the obturator nerve in the minor pelvis. The technique of obturator nerve block by local anaesthesia is described and its efficacy is demonstrated in 21 patients.     

Ultrasound-guided femoral nerve block

Femoral nerve block is well suited for surgery on the anterior aspect of the thigh and knee. The primary indication of continuous femoral nerve block is pain management after major femoral or knee surgery. Ultrasound image guidance for femoral nerve block can improve block success rate and decrease complications. We describe the ultrasound scanning, needling technique, and catheter insertion technique for single-dose technique and continuous infusion technique.     

Ultrasound-guided sciatic nerve block

Theoretically, sciatic nerve block can be used alone or in combination with lumbar plexus block or femoral nerve block for anesthesia and/or analgesia of lower limb surgery. However, clinical use of sciatic nerve block was limited by technical difficulties in performing the block since techniques used relies only on surface anatomical landmarks. Recent advances in ultrasound technology allow direct visualization of nerves and other surrounding structures and have increased the interest in performing many kinds of peripheral nerve blocks including sciatic nerve block. Preliminary data suggest that ultrasound-guided technique can help perform the sciatic nerve block more reliably and safely. In this article we describe the anatomy of the sciatic nerve, sonographic features, and technique of three major approaches including subgluteal, anterior, and popliteal approaches. The use of this technique for postoperative analgesia is also discussed.     

闭孔神经阻滞的研究进展

背景闭孔神经阻滞（obturator nerve block,ONB）可用于缓解大腿内收肌痉挛及髋关节疼痛、抑制经尿道膀胱肿瘤电切术中闭孔神经反射等。近年来,随着人们对神经阻滞麻醉的再度关注,ONB的应用与研究也随之增多。目的概述及评价ONB适应证及穿刺方法,为临床及研究工作提供参考。内容阐述ONB的适应证,荟萃分析ONB的不同穿刺入路及方法。趋向随着ONB临床应用的不断普及,更具优势的阻滞方法也会不断涌现。     

Ultrasound-guided nerve block: brachial plexus block

Ultrasonographic guidance has been introduced as an aid to nerve localization, for brachial plexus blockade in the interscalene and infraclavicular regions. Ultrasound-guided interscalene approach and infraclavicular approach were established as an excellent method to provide good analgesia during surgery and relieve post-surgical pain after shoulder or upper arm surgery and forearm or hand surgery respectively. Single shot injection and continuous catheter approach in both nerve blocks were described together with clinical key points based on the ultrasound images.     

Ultrasound-guided peripheral nerve blocks for anterior cruciate ligament reconstruction: effect of obturator nerve block during and after surgery

Purpose  

Three studies were conducted to determine whether and how the obturator nerve bears relevance to intra- and postoperative pain in patients undergoing anterior cruciate ligament (ACL) reconstruction using a hamstring autograft.     

Accurate obturator nerve block in transurethral surgery

Twenty-two patients with ureteral stones underwent twenty-four-hour urinary excretion studies of calcium, phosphorus, and uric acid before and after stone elimination from the urinary tract. Comparison of pre- and post-stone elimination studies showed no significant differences suggesting that the presence of stones in the urinary tract has little influence on the twenty-our-hour urinary excretion of calcium, phosphorus, and uric acid.     

Ropivacaine-induced grand mal convulsion after obturator nerve block

We describe a patient to whom ropivacaine 150 mg had been administered during obturator nerve blockade and developed grand mal convulsions because of inadvertent i.v. injection. Venous blood samples were taken 15, 32 and 52 min after the convulsion. The measured total plasma concentrations of ropivacaine were 4.5, 3.5 and 2.9 microg x ml(-1) respectively. The peak plasma concentration at the time of the inadvertent i.v. injection was estimated to be 6.6 microg x ml(-1). The patient recovered uneventfully.     

膀胱肿瘤电切术中行闭孔神经阻滞防止闭孔神经反射的效果分析

目的 探讨经尿道膀胱肿瘤电切术中采用闭孔神经阻滞防止闭孔神经反射的临床效果.方法 对214例膀胱癌患者行经尿道电切术,治疗组113例在腰-硬联合麻醉基础上进行闭孔神经阻滞,而对照组101例仅行单纯腰-硬联合麻醉.结果 治疗组闭孔神经反射发生率（9.7%）明显低于对照组（22.8%）（P〈0.05）,两组复发率差异无统计学意义（21.2% vs 25.7%,P＆gt;0.05）.结论 在经尿道膀胱肿瘤电切术中采取闭孔神经阻滞能明显减少闭孔神经反射的发生,提高手术的安全性和有效性,临床效果良好.     

Adding a selective obturator nerve block to the parasacral sciatic nerve block: an evaluation

Our aim was to objectively evaluate the efficacy of obturator nerve anesthesia after a parasacral block. Patients scheduled for knee surgery had a baseline adductor strength evaluation. After a parasacral block with 30 mL 0.75% ropivacaine, sensory deficit in the sciatic distribution (temperature discrimination) and adductor strength were assessed at 5-min intervals. Patients with an incomplete sensory block (defined as a temperature discrimination score of less than 2 in the 3 cutaneous distributions of the sciatic nerve tested) 30 min after the parasacral block were excluded from the study. Subsequently, a selective obturator block was performed with 7 mL 0.75% ropivacaine and adductor strength was reassessed at 5 min intervals for 15 min. Finally, a femoral block was performed using 10 mL 0.75% ropivacaine. Patient discomfort level during each block was assessed using a visual analog scale (VAS). Thirty-one patients completed the study. Five patients were excluded as a result of inadequate sensory block in the sciatic distribution 30 min after the parasacral block (success rate of 89%). Thirty min after the parasacral block, adductor strength decreased by 11.3% +/- 7% compared with baseline (85 +/- 24 versus 97 +/- 28 mm Hg, P = 0.002). Fifteen min after the obturator nerve block, adductor muscle strength decreased by an additional 69% +/- 7% (16.6 +/- 15 versus 85 +/- 24 mm Hg, P < 0.0001). VAS scores were similar for all blocks (26 +/- 19, 28 +/- 24, and 27 +/- 19 mm for parasacral, obturator, and femoral respectively). Four parasacral blocks were simulated in 2 fresh cadavers using 30 mL of colored latex solution. The spread of the die in relation to the obturator nerve was assessed. Injection of 30 mL colored latex into cadavers resulted in spread of the injectate restricted to the sacral plexus. These findings demonstrate the unreliability of parasacral block to achieve anesthesia of the obturator nerve. A selective obturator block should be considered in the clinical setting when this is desirable.     

Sonographic imaging of the obturator nerve for regional block

BACKGROUND AND OBJECTIVES: Today, there is a growing appreciation of the importance of the obturator nerve in clinical anesthesia. The aim of this study is to describe the ultrasound appearance of the obturator nerve for potential utility in guiding these nerve blocks. METHODS: We scanned left and right inguinal regions of 20 volunteers lateral and distal to the pubic tubercle (PT) and assessed visibility, size and shape, and depth from the skin of common obturator nerves and their associated divisions. In addition to the volunteer study, we retrospectively reviewed a clinical series of obturator nerve blocks performed with ultrasound guidance and nerve stimulation. RESULTS: The obturator nerve can be sonographically visualized by scanning along the known course of the nerve; the anterior division characteristically converges toward the posterior division along the lateral border of the adductor brevis muscle to form the common obturator nerve more proximally. In the set of 20 volunteers, 25% (10/40) of common, 85% (34/40) of anterior, and 87.5% (35/40) of posterior obturator nerves were sonographically identified. The common obturator nerve was visualized 1.3 +/- 1.5 cm distal and 2.3 +/- 1.2 cm lateral to the PT. Divisions were visualized 2.1 +/- 2.0 cm distal and 2.1 +/- 1.2 cm lateral to the PT. The nerves (common, anterior, and posterior) averaged 2.7 +/- 1.2 mm, 1.4 +/- 0.6 mm, and 1.7 +/- 0.6 mm in anterior-posterior dimension and 9.0 +/- 4.3 mm, 9.6 +/- 3.9 mm, and 10.9 +/- 4.1 mm in medial-lateral dimension and were 25.9 +/- 7.6 mm, 15.5 +/- 3.9 mm, and 29.3 +/- 7.9 mm below the skin surface. The common obturator nerve and its anterior and posterior divisions are all relatively flat nerves with average anterior-posterior/medial-lateral dimension ratios of 0.32, 0.18, and 0.18, respectively. In the clinical series, nerve identification was confirmed with nerve stimulation (n = 6 block procedures, mean threshold stimulating current for evoked adductor contraction = 0.70 +/- 0.14 mA). CONCLUSIONS: The obturator nerve and its divisions are the flattest peripheral nerves yet described with ultrasound imaging. Knowledge of the obturator nerve's ultrasound appearance facilitates localization of this nerve for regional block and may increase success of such procedures.     

A report on 107 cases of obturator nerve block

The obturator nerve passes in close proximity to the inferolateral bladder wall. Transurethral resection of bladder tumors close to these areas may stimulate the obturator nerve, causing violent adductor contraction and possible inadvertent bladder perforation. To avoid this reaction, local anesthetic blockade of the obturator nerve as it passes through the obturator canal is effective to stop adductor spasm during spinal anesthesia. We performed obturator nerve block in 107 cases by use of insulated needle and nerve stimulator, and measured the depth of the obturator nerve and that of the pubic tubercle. Obesity index was positively correlated with the depth of the obturator nerve as well as the pubic tubercle. However, no correlation was found between the obesity index and the difference of the depth of the obturator nerve and the depth of the pubic tubercle. It is suggested that if the needle is advanced in the direction of the obturator canal about 40mm further after reaching the pubic tubercle, the needle reaches the obturator nerve.     

Pubic tubercle side approach to the obturator nerve block

BACKGROUND: The authors describe the pubic tubercle side approach of the obturator nerve block for the management of adductor muscle constriction associated with the transurethral resection of the lateral wall bladder tumor. METHODS: The pubic tubercle side approach of the obturator nerve block was performed by a inserting needle at the midpoint of the femoral artery and the pubic tubercle. After the needle encountered the superior ramus of pubis, the needle was redirected vertical or slightly caudal, passeing the vicinity of the inferior margin of the superior ramus of pubis, and then advanced to the trunk of the obturator nerve. The obturator nerve was identified by its response to nerve stimulation. The pubic tubercle side approach using more than 5 ml of 1.0% lidocaine was performed by a single injection until there was no response to nerve stimulation. On the other hand, by the traditional approach to the obturator nerve block, after the initial local anesthetic injection the needle was redirected lateral and slightly caudal. If the response to nerve stimulation was still elicited, more local anesthetic was administered. RESULTS: Evaluation of the efficacy of the pubic tubercle side approach was performed in-terms of quantity of the local anesthetic used and the success rate. In comparison with the traditional approach, a smaller dose of local anesthetic was used in spite of the higher success rate. CONCLUSIONS: The pubic tubercle side approach of the obturator nerve was useful and without complications in comparison with the traditional approach.     

超声引导下闭孔神经阻滞在经尿道膀胱肿瘤电切术中预防闭孔神经反射的效果

目的通过对比不同麻醉方式下闭孔神经反射的发生情况,探讨经尿道膀胱肿瘤电切术中预防闭孔神经反射的有效方式。方法选取需行经尿道膀胱肿瘤电切术的膀胱侧壁肿瘤患者160例,男134例,女26例,ASAⅠ~Ⅲ级,随机分为四组:全凭静脉麻醉组(G组),腰-硬联合麻醉组(C组),腰-硬联合麻醉复合静脉麻醉组(V组),腰-硬联合麻醉复合闭孔神经阻滞(obturator nerve block,ONB)组(O组),每组40例。记录不同麻醉方式下闭孔神经反射的发生情况。结果O组闭孔神经反射发生率(7.5%)明显低于C组(32.5%,P=0.005)和V组(40.0%,P=0.001),与G组闭孔神经反射发生率(5.0%)差异无统计学意义(P=0.644)。结论腰-硬联合麻醉复合闭孔神经阻滞与全凭静脉麻醉均可有效预防闭孔神经反射的发生。