Ultrasound-guided Obturator Nerve Block Research Articles

Effect of Ultrasound-guided Obturator Nerve Block on Complications in Transurethral Resection for Bladder Cancer

Effect of Ultrasound-guided Obturator Nerve Block on Complications in Transurethral Resection for Bladder Cancer

Application of Self-Adaptive Medical Ultrasonic Imaging Algorithm-Based Obturator Nerve Block in Transurethral Resection of Bladder Tumor

The application values of ultrasound-guided obturator nerve block (ONB) optimized by self-adaptive algorithm in transurethral resection of bladder tumor (TURBT) are investigated. For this purpose, total of 50 patients receiving TURBT areselected and randomly rolled into a control group (Ctrl group, ONB under traditional resectoscope) and an experimental group (Exp group, self-adaptive algorithm-based ultrasound-guided ONB (algorithm+ultrasound ONB)). Each group contains 25 cases. The results of the comprehensive assessment of each index showed that the self-adaptive algorithm enhanced the solution of ultrasonoscopy, which was morebeneficial for the intraoperative guidance on block. The success rate of the block in the Exp group reached 100%, higher than that in the Ctrl group (92%). The block time was 6.53±1.28 minutes, which was obviously shorter than that in the Ctrl group (10.34±1.76 minutes). The incidence of complications (IoC) (16%) was significantly lower than that in the Ctrl group (36%). Besides, postoperative visual analogue scale/score (VAS) (2.01±0.84 points) was remarkably lower based on the score in theCtrl group (4.73±1.15 points). The above differences all show statistical significance (P <0.05). To sum up, self-adaptive algorithm could enhance the quality of surgical ultrasound-guided ONB, which showed significant values in the prevention of obturator nerve reflex, postoperative analgesia for patients, and the recovery.

Can different positions facilitate block application in ultrasound-guided obturator nerve block? A prospective comparative study

<b>Objective</b>: We aimed to compare the distances of the landmarks to the skin, image quality, and ease of application in the ultrasound-guided obturator nerve block (ONB) in different positions.<br /> <b>Materials and Methods:</b> 40 volunteers aged between 20-65 years were included in the study. The distances of the landmarks (anterior and posterior branches of the obturator nerve; junction of the abductor longus and abductor brevis muscles with the pectineus muscle) to the skin, which were taken as a reference for the ultrasound-guided obturator block, were measured and compared in 3 different positions (P1=Neutral position; P2=45<sup>o</sup> Abduction; and P3=Flexed knee) given to the leg. We also evaluated the quality of the ultrasound image and the ease of application in each measurement by assigning a subjective observer score and comparisons were made for three positions.<br /> <b>Results:</b> While the mean of the distances of the landmarks to the skin were the shortest in P3 and the longest in P1 position, there was no significant difference between the groups (p>0.05).<b> </b>A statistically significant difference was observed between P1 and P3 in the distance of the junction of the muscles to the skin surface (p<0.05). The highest score for the clarity of ultrasound images and ease of accessing the measurement points was the P3 position (p=0.00). In addition, in our correlation analysis, we found that as the distance of the landmarks to the skin surface decreased, the image clarity and the ease of access to the obturator nerve (score) increased, where p<0.05.<br /> <b>Conclusions</b>: In ultrasound guided ONB, in P3 position landmarks get closer to the skin, and image clarity and ease of detection for landmarks increases in parallel with this position. As a result, the ultrasound guided ONB can be best done by giving flexed knee position.

Pilot study of the effect of therapeutic photobiomodulation on postoperative pain in knee arthroplasty

Nine participants undergoing primary TKA submitted to spinal anesthesia, sedation, ultrasound-guided obturator and Femoral nerve Block analgesia, and photobiomodulation Therapy (FBMT) were evaluated regarding postoperative pain and morphine consumption. FBMT sessions were performed in the Immediate Postoperative period (IPO) and after 24 hours. Participants received 16.7±15 mg of morphine up to the third postoperative day. At IPO, mean pain score was 4.8±3.2 and 5.6±3.5, at rest and on movement, respectively. Photo biomodulation therapy can be considered an option for mitigating pain for patients undergoing TKA.

Obturator Nerve Blockade vs. Neuromuscular Blockade for the Prevention of Adductor Spasm in Patients Undergoing Transurethral Resection of Bladder Tumors: A Randomized Controlled Trial.

The obturator nerve runs along the posterolateral walls of the bladder and electrosurgical stimulation in this region can result in adductor spasm which can occur suddenly and unexpectedly with potentially catastrophic results. Sixty patients were prospectively randomized to receive either a single-injection ultrasound-guided obturator nerve block (ONB) or intravenous rocuronium after induction of general anesthesia (i.e., neuromuscular block [NMB]). The primary objective was to compare the incidence of adductor spasm during posterolateral bladder tumor resection when ONB or NMB was used. Secondary objectives included assessment of fall risk and incidence of adverse events. Five patients in the ONB group and six in the NMB group had nonlateral wall lesions. One patient in the ONB group suffered a cardiac arrest after induction of general anesthesia. Of the remaining 48 patients, six (10.2%) experienced adductor spasm. Most of these patients were in the NMB group (5/24, 20.8%), with only one patient (1/24, 4.2%) experiencing obturator reflex in the ONB group; this difference was not statistically significant (P=0.19). Patients in the ONB group had a greater decrease in mean hip adductor strength. Our study population was found to be at high risk of falls before surgery. There were no statistically significant group differences in the Timed Up and Go test, with time to perform the test increasing in both groups. Both techniques are safe and efficacious for preventing adductor spasm. Our data and experience suggest that the ONB is relatively easy to perform and should be considered in patients with posterolateral bladder tumors.

Twitching of the Pectineus Muscle Under Ultrasound-Guided Complete Obturator Nerve Block at the Inguinal Crease: A Case Report

Introduction: This report showed that clinically significant adductor muscle contraction can be possible even when the anterior and posterior branches of the obturator nerve are completely blocked. Case Presentation: A 66-year-old male patient visited Gil Medical Center, Gachon University College of Medicine, Incheon, South Korea during the year 2016. He underwent transurethral resection of the bladder (TURB) of a bladder tumor under spinal anesthesia and obturator nerve block (ONB). ONB was performed at the right-side inguinal crease by an ultrasound-guided block of the anterior and posterior branches. At the beginning of surgery, he exhibited grade IV obturator reflex; therefore, general anesthesia was applied and the surgery completed. After the effect of neuromuscular blockade had been completely reversed, we confirmed twitching of the pectineus muscle by ultrasound using a nerve stimulator (stimulation current 0.3 mA). Main branches of the right obturator nerve were still completely blocked when we rechecked the previously blocked-site (stimulation current 2 mA). Conclusions: The described case cautions that investigators must be aware more than two branches may pass adjacent to interfascial layers at the inguinal crease level and that a missed obturator nerve branch might result in severe adductor muscle contraction. We report this observation and suggest the possibility of an anatomical variant that requires the need for nerve stimulation and ultrasound for obturator nerve block verification.

Effectiveness of Ultrasound Guided Obturator Nerve Block in Transurethral Resection Operations

Effectiveness of Ultrasound Guided Obturator Nerve Block in Transurethral Resection Operations

Ultrasound-Guided Obturator Nerve Block: A Focused Review on Anatomy and Updated Techniques.

This review outlines the anatomy of the obturator nerve and the indications for obturator nerve block (ONB). Ultrasound-guided ONB techniques and unresolved issues regarding these procedures are also discussed. An ONB is performed to prevent thigh adductor jerk during transurethral resection of bladder tumor, provide analgesia for knee surgery, treat hip pain, and improve persistent hip adductor spasticity. Various ultrasound-guided ONB techniques can be used and can be classified according to whether the approach is distal or proximal. In the distal approach, a transducer is placed at the inguinal crease; the anterior and posterior branches of the nerve are then blocked by two injections of local anesthetic directed toward the interfascial planes where each branch lies. The proximal approach comprises a single injection of local anesthetic into the interfascial plane between the pectineus and obturator externus muscles. Several proximal approaches involving different patient and transducer positions are reported. The proximal approach may be superior for reducing the dose of local anesthetic and providing successful blockade of the obturator nerve, including the hip articular branch, when compared with the distal approach. This hypothesis and any differences between the proximal ONB techniques need to be explored in future studies.

A Cadaveric Study of Ultrasound-Guided Subpectineal Injectate Spread Around the Obturator Nerve and Its Hip Articular Branches

The femoral and obturator nerves are assumed to account for the primary nociceptive innervation of the hip joint capsule. The fascia iliaca compartment block and the so-called 3-in-1-block have been used in patients with hip fracture based on a presumption that local anesthetic spreads to anesthetize both the femoral and the obturator nerves. Evidence demonstrates that this presumption is unfounded, and knowledge about the analgesic effect of obturator nerve blockade in hip fracture patients presurgically is thus nonexistent. The objectives of this cadaveric study were to investigate the proximal spread of the injectate resulting from the administration of an ultrasound-guided obturator nerve block and to evaluate the spread around the obturator nerve branches to the hip joint capsule. Fifteen milliliters of methylene blue was injected into the interfascial plane between the pectineus and external obturator muscles in 7 adult cadavers. The spread of the injectate into the obturator canal and around the obturator and accessory obturator nerve branches to the hip joint was evaluated by subsequent dissection. The injected dye spread into the obturator canal and colored all obturator branches to the hip joint capsule in all 14 sides. Furthermore, the accessory obturator nerve was present in 3 sides (21%), and the nerve and its branches to the hip joint capsule were colored in all cases. In cadavers, injection of 15 mL of methylene blue into the interfascial plane between the pectineus and the external obturator muscle effectively spreads proximally to reach the obturator canal, as well as the obturator nerve branches to the hip joint capsule and the accessory obturator nerve.

Poster 448 Obturator Neuropathy after Lumbar Fusion and Resolution with Ultrasound-Guided Obturator Nerve Block: A Case Report

Poster 448 Obturator Neuropathy after Lumbar Fusion and Resolution with Ultrasound-Guided Obturator Nerve Block: A Case Report

RETRACTED: Detection of large perforating artery by ultrasound prescan before obturator nerve block

An obturator nerve block improves the quality of postoperative analgesia after lower extremity surgery [1]. An ultrasound-guided obturator nerve block is simpler to perform and more reliable than other landmark techniques [2]. We report a case where a large perforating artery was detected by ultrasound prescan before applying the obturator nerve block. A 75-year-old man with bladder cancer was scheduled to undergo transurethral resection of the bladder tumor. After induction of the spinal anesthesia, bilateral obturator nerve blocks were attempted by performing the interfascial approach at the level of the femoral crease. An ultrasound prescan indicated the presence of a large artery near the anterior branch of the right obturator nerve between the adductor longus and the adductor brevis (Figure). By using the ultrasound probe, we detected that it branched out from the right deep artery of the thigh. Therefore, the artery was considered a large perforating artery from the right deep artery of thigh. We could not detect a similar abnormal large performing artery from the left deep artery. We performed bilateral obturator nerve block to avoid the large performing artery from the right deep artery. An unintentional pucture of a large perforating artery puncture during obturator nerve block can cause some complications such as hematoma and local anesthetic intoxication. We recommend that the vasculature be confirmed by an ultrasound prescan prior to performing an obturator nerve block.

Adductor accessorius - an unusual supernumerary adductor muscle of thigh.

The knowledge of variant anatomy of medial compartment of thigh is extremely important in surgical procedures requiring obturator nerve block. The nerve block is also recommended for providing additional analgesia following major knee surgeries and for relieving painful adductor muscle spasm. The interfascial injection technique is commonly followed in ultrasound guided obturator nerve block. For this procedure it is imperative to identify the adductor muscles on sonography to inject the anesthetic solution in the intermuscular fascial planes. The presence of an additional muscle can prove useful in myocutaneous flap surgeries for reconstruction especially of perineum. We hereby report a case of such an anomalous supernumerary adductor muscle present between adductor brevis and proximal part of adductor magnus, in an adult Indian male cadaver, recorded during routine dissection in Department of Anatomy, Vardhman Mahavir Medical College and Safdarjung Hospital. The muscle was innervated by the posterior division of obturator nerve. The morphology, embryological basis and clinical aspects are also discussed.

Efficacy of ultrasound-guided obturator nerve block using proximal interfascial technique

Objective To evaluate the efficacy of ultrasound-guided obturator nerve block using proximal interfascial technique. Methods Seventy ASA physical status Ⅰ or Ⅱ patients of both sexes, aged 43-82 yr, with body mass index of 18.0-30.5 kg/m2, scheduled for elective trans-urethral resection of bladder tumor, were randomly divided into 2 groups(n=35 each)using a random number table: remote interfascial technique group(group R)and proximal interfascial technique group(group P). In group R, interfascial injections at 2 planes, lateral and deep to the adductor brevis muscle, were carried out with 0.375% ropivacaine 7.5 ml to block each obturator nerve branch separately.In group P, 0.375% ropivacaine 15.0 ml was injected under ultrasound guidance at the interfascial plane inferior to the superior pubic ramus(between the pectineus and obturator externus). The strength of thigh adduction was measured before injection(baseline)and at 5, 10, and 15 min after injection.Then combined spinal-epidural anesthesia was performed at L3, 4 interspace.The 50% strength reduction indicated a successful block.The block performance time was recorded.The success rate of block at 15 min after injection was calculated.It was considered clinically effective when obvious muscle twitching interfering with the surgical procedure did not appear.The clinical outcome was assessed, and the effective rate of clinical outcome was calculated. Results Compared with group R, the block performance time was significantly shortened, the success rate of block, strength reduction at 10 and 15 min after injection, and clinical outcome were increased in group P. There were no significant differences in the effective rate of clinical outcome. Conclusion Compared with remote interfascial technique, ultrasound-guided obturator nerve block using proximal interfascial technique provides easier and rapid procedure, higher success rate of block and better clinical outcome of block. Key words: Nerve block; Obturator nerve; Ultrasonography

Ultrasound-guided obturator nerve block: effects and spread of distal interfascial injection

Ultrasound-guided obturator nerve block: effects and spread of distal interfascial injection

Ultrasound-Guided Obturator Nerve Block

Ultrasound-Guided Obturator Nerve Block

Ultrasound-Guided Obturator Nerve Block

Interfascial injection of local anesthetic under ultrasound guidance has been proposed as a new technique for performing an obturator nerve block. We hypothesized that interfascial needle placement could supplant nerve stimulation as the end point for local anesthetic injection during ultrasound-guided obturator nerve block after the division of the obturator nerve. Fifty spinal anesthesia patients who had experienced unilateral adductor muscle spasm during transurethral bladder tumor resection were randomly allocated to receive either 5 mL of lidocaine 2% injected under ultrasound guidance into the interfascial plane between the adductor longus and the adductor brevis and between the adductor brevis and the magnus muscles (US group) or an injection of 5 mL of lidocaine 2% in combination with nerve stimulation after identification of the divisions of the obturator nerve (USENS group). At 5, 10, and 15 minutes after block placement, muscle spasm was assessed by an independent observer masked to treatment allocation. The primary outcome was motor block onset time. Secondary outcomes were block performance time, total anesthesia-related time, motor block success at 15 minutes, and number of needle passes. Motor block onset time did not differ between the 2 groups (6.2 minutes for USENS versus 7.2 minutes for US group, P = 0.225), block performance time was longer in the USENS than in the US group (3.0 versus 1.6 minutes, P < 0.001), and total anesthesia-related time did not differ between the 2 groups (9.2 versus 8.9 minutes, P = 0.71). Block success rate at 15 minutes was 100% in the USENS group and 88% in the US group (P = 0.23). There was no difference in the number of needle passes (2.3 versus 2.1, P = 0.28). In ultrasound-guided obturator nerve block performed after the division of the nerve, injection of local anesthetic between the planes of the adductor muscles is comparable to nerve stimulation.

Ultrasound guided obturator nerve block: a single interfascial injection technique

We describe a new technique of single interfascial injection for 25 patients scheduled for transurethral bladder tumor resection. An ultrasound probe was placed at the midline of inguinal crease and moved medially and caudally to visualize the fascial space between the adductor longus (or pectineus) and adductor brevis muscles. We injected 20 mL 1% lidocaine containing epinephrine into the interfascial space using a transverse plane approach to make an interfascial injection, not an intramuscular swelling pattern. And just distally, firm pressure was applied for 3 min. Afterwards, surgery was performed under spinal anesthesia. The time required for identification and location of the nerve was 20 ± 15 and 30 ± 15 s, respectively. Adductor muscle strength, which was measured with a sphygmomanometer, decreased in all patients, from 122 ± 26 mmHg before blockade to 63 ± 11 mmHg 5 min after blockade. No movement or palpable muscle twitching occurred in 23 cases, slight movement of the thigh not interfering with the surgical procedure was observed in 1 case, thus the obturator reflex was successfully inhibited in 96% of cases. Ultrasound-guided single interfascial injection is an easy and successful technique for obturator nerve block.

Efficacy of ultrasound-guided obturator nerve block in transurethral surgery

Background:During transurethral resection surgery (TUR), accidental stimulation of the obturator nerve can cause violent adductor contraction, leading to serious intraoperative complications. General anesthesia with muscle relaxation is currently the preferred technique for TUR surgery. Spinal anesthesia combined with obturator nerve block has also been used for TUR surgery in geriatric population. Blind, anatomical methods for identifying the obturator nerve are often unsatisfactory. Therefore, we conducted this prospective study to validate the efficacy of ultrasound-guided obturator nerve block (USONB) during TUR procedures.Methods:Eighteen male patients undergoing TURP surgery under spinal anesthesia were included in the study. Bilateral USONB with maximum 20 ml of 1% lidocaine per patient was performed. An independent observer was present to monitor any adduction movements during the operation and to record patient and surgeon satisfactions.Results:In all patients, obturator nerve was visualized from the first attempt, requiring an average of 4.3 min for blocking of each side. USONB was successful (97.2%) in preventing an adductor spasm in all except one patient. Patient’s and surgeon’s satisfaction were appropriate. In all patients, adductor muscle strength recovered fully within 2 h following the surgical procedure.Conclusions:USONB is safe and effective during TUR surgery. It provides optimal intra-and postoperative conditions.

Ultrasound-Guided Obturator Nerve Block: A Sonoanatomic Study of a New Methodologic Approach

Obturator nerve block is one of the most technically challenging regional anesthesia techniques. Recently, the characteristics of the nerve have been described using ultrasound. However, clinical application of proximal ultrasound-guided obturator nerve block on patients has not been reported. In this study, we used ultrasound to describe the anatomical localization of the obturator nerve and its two branches in cadavers, volunteers, and also patients. A hyperechoic triangular shape formed by the superior pubic ramus, posterior margin of the pectineus muscle and anterior aspect of the external obturator muscle containing the obturator vessels and nerve was defined by ultrasound imaging in cadavers. In eight volunteers, bilateral obturator nerve images were obtained and the distances to specific landmarks (femoral artery, femoral vein, and pubic tubercle) were recorded. Ultrasound-guided obturator nerve block was further performed in 15 patients by using the previously defined approach. The final distance of the needle tip to the femoral artery, distances between the needle insertion point to the pubic tubercle and the depth of needle insertion were recorded. The rates of common obturator nerve, anterior and branching obturator nerve pattern visibility with ultrasound were determined in 12/16, 13/16, and 7/16 sites in volunteers, respectively. Mean (SD) values of critical landmarks obtained from volunteers were obturator nerve-femoral vein 12.9 +/- 2.9 mm and obturator nerve-pubic tubercle 19.9 +/- 2.6 mm. Mean measurements obtained from patients were: femoral artery- needle tip 18.5 +/- 2.4 mm, needle depth 48.3 +/- 10.4 mm, pubic tubercle- needle insertion point (horizontal) 18.8 +/- 2.0 mm, and pubic tubercle- needle insertion point (vertical) 21.1 +/- 2.9 mm. Visual analog scale scores obtained from patients at 1 and 24 h were lower compared to baseline values (P < 0.001). Ninety-three percent (14 of 15) of the patients reported satisfaction from the block. Landmarks defined in this clinical trial can be used in patients for obturator nerve block with ultrasound guidance.

Ultrasound-Guided Obturator Nerve Block: A Preliminary Report of a Case Series

Obturator-nerve block improves analgesia for knee surgery. Traditional techniques rely on surface landmarks, which can be variable and result in excessive performance times and multiple needle passes. The objective of this study was to evaluate a novel ultrasound-guided technique for localizing the obturator nerve. A total of 22 patients undergoing anterior cruciate ligament repair had ultrasound-guided obturator-nerve blocks. Needles were directed under real-time ultrasound guidance. Endpoint for injection consisted of identifying contact of the tip of an insulated needle to nerve confirmed by adductor muscles' contraction. Local anesthetic was injected, and block was evaluated within 30 minutes. After that, ultrasound-guided sciatic-femoral blocks were placed for surgical purposes. Data collected included: time required for nerve identification, minimum stimulating current, number of attempts for correct identification, preblock and postblock adductor muscles' strength, sensory-nerve block, and quality of surgical anesthesia. In 91% of cases, the obturator nerve was correctly identified on first attempt within 30 +/- 23 seconds, as a hyperechoic flat or lip-shaped structure with internal hypoechoic dots. Minimal intensity of current to nerve stimulation was 0.30 +/- 0.08 mA. All patients exhibited decreases in adductor strength. Sensory territories were variable, with no cutaneous distribution in 32% of the patients. Small-dose opioid supplementation was required in 14% of the patients, but none required general anesthesia to complete surgery. These preliminary data suggest that ultrasound-guided obturator-nerve identification and block are technically easy and highly successful.