Interscalene brachial plexus block for shoulder surgery: a proximal paresthesia is effective.

This study was designed to determine whether the location of paresthesias is related to the success of interscalene blocks in providing anesthesia for shoulder surgery. Interscalene blocks were performed in 45 patients presenting for elective shoulder surgery. Interscalene injections of 33-55 mL of 1.5% mepivacaine with epinephrine were performed after the first elicited paresthesia to the shoulder, arm, forearm, or hand. In 20 patients (45%), the initial elicited paresthesia was to the shoulder, whereas in 25 patients (55%), the first paresthesia was reported as distal to the shoulder. All patients developed brachial plexus anesthesia adequate for shoulder surgery. The time-course of onset of motor block as evaluated at the shoulder and elbow was not different between patients with shoulder paresthesias and those with more distal paresthesias. Handgrip strength was quantitatively evaluated with a dynamometer, and both paresthesia groups showed similar decrements in hand strength except at the end of the measurement period, when patients with distal paresthesias had a significantly weaker handgrip than patients with shoulder paresthesias. We recommend that paresthesias to the shoulder be accepted in performing interscalene blocks for patients undergoing shoulder surgery.     

Skin temperature after interscalene brachial plexus blockade

BACKGROUND AND OBJECTIVES: In neuraxial anesthesia, increase of skin temperature is an early sign of successful block. Yet, during peripheral nerve block of the lower extremity, increase in skin temperature is a highly sensitive, but late sign of a successful block. We hypothesized that after interscalene brachial plexus block, a rise in skin temperature follows impairment of sensation during successful nerve block and occurs only distally, as observed in the lower extremity. METHODS: In the present study, we prospectively evaluated the changes in skin temperature after interscalene brachial plexus blockade in 45 patients scheduled for elective shoulder surgery. We assessed pinprick and cold sensation as well as skin temperature at sites of the skin innervated by the median, ulnar, radial, axillary and musculocutaneous nerve. RESULTS: At the skin areas innervated by the axillary and musculocutaneous nerve, skin temperature did not increase after successful block. At the distal sites, innervated by the median, ulnar, and radial nerve, skin temperature increased significantly (1.9-2.1 degrees C within 30 min) after successful block while it did not after failed nerve block or on the contralateral side. In these areas attenuation of skin sensation preceded a measurable rise in skin temperature (> or =1 degrees C) in 56.3% of nerve blocks, occurred at the same time in 35.2%, and in 8.5% the temperature rise occurred first. CONCLUSIONS: Assessment of skin temperature cannot predict the success of an interscalene brachial plexus block of the axillary and musculocutaneous nerve. Distally, the increase of skin temperature has a high sensitivity and specificity but occurs later than the loss of sensory and motor functions. Therefore, the measurement of skin temperature during interscalene blockade is of limited clinical value.     

Inability to Consistently Elicit a Motor Response following Sensory Paresthesia during Interscalene Block Administration

Background: Two methods of nerve block based on eliciting neural feedback with the block needle currently exist. The paresthesia technique uses sensory feedback to ascertain that the needle tip is close to the nerve. By contrast, a peripheral nerve stimulator makes use of motor responses to electrical stimulation. The relation of motor responses to an electrical peripheral nerve stimulator and sensory nerve contact (paresthesia) had not been studied.

Methods: Thirty consecutive unpremedicated patients who presented for shoulder surgery with interscalene block anesthesia were prospectively studied. Interscalene block was performed by the single paresthesia method of Winnie, using an insulated or noninsulated needle connected to a peripheral nerve stimulator with the power off. At the precise point of paresthesia, the peripheral nerve stimulator was turned on, and the current was slowly increased to 1.0 mA with a pulse width of 0.2 ms. Presence and location of any motor responses were observed and recorded.

Results: All patients had easily elicited paresthesias. The site of first paresthesia was to the shoulder in 73% of patients. Only 30% of patients exhibited any motor response to electrical stimulation up to 1.0 mA. There was no relation between site of paresthesia and associated motor nerve response.     

Inability to consistently elicit a motor response following sensory paresthesia during interscalene block administration

BACKGROUND: Two methods of nerve block based on eliciting neural feedback with the block needle currently exist. The paresthesia technique uses sensory feedback to ascertain that the needle tip is close to the nerve. By contrast, a peripheral nerve stimulator makes use of motor responses to electrical stimulation. The relation of motor responses to an electrical peripheral nerve stimulator and sensory nerve contact (paresthesia) had not been studied. METHODS: Thirty consecutive unpremedicated patients who presented for shoulder surgery with interscalene block anesthesia were prospectively studied. Interscalene block was performed by the single paresthesia method of Winnie, using an insulated or non-insulated needle connected to a peripheral nerve stimulator with the power off. At the precise point of paresthesia, the peripheral nerve stimulator was turned on, and the current was slowly increased to 1.0 mA with a pulse width of 0.2 ms. Presence and location of any motor responses were observed and recorded. RESULTS: All patients had easily elicited paresthesias. The site of first paresthesia was to the shoulder in 73% of patients. Only 30% of patients exhibited any motor response to electrical stimulation up to 1.0 mA. There was no relation between site of paresthesia and associated motor nerve response. CONCLUSION: Elicitation of paresthesia does not translate to an ability to elicit a motor response to a peripheral nerve stimulator in the majority of patients.     

无异感肌间沟臂丛阻滞的临床应用（附327例报告）

目的 探讨无异感肌间沟臂丛阻滞的效果及异感与阻滞的关系. 方法 327例锁骨、肩部及上肢择期或急诊手术患者.用不探寻异感的方法进行肌间沟臂丛阻滞,观察其阻滞效果.手术无疼痛、手术有疼痛复合氟芬合剂能完成手术为有效. 结果 全部病例在阻滞过程中均未出现异感,其中有效324例（99.1％）,失败3例. 结论 不探寻异感肌间沟臂丛阻滞方法简单,易于掌握,效果良好,值得推广.     

Interscalene brachial plexus anaesthesia with small volumes of ropivacaine 0.75%: effects of the injection technique on the onset time of nerve blockade

BACKGROUND AND AIM: We evaluated the effect of the injection technique on the onset time and efficacy of interscalene brachial plexus anaesthesia. METHODS: With Ethical Committee approval and written consent, 30 patients undergoing elective shoulder acromioplasty or capsuloplasty were randomly allocated to receive interscalene brachial plexus block with 20 mL of ropivacaine 0.75% by using either a single injection (Single group, n = 15) or multiple injection (Multiple group, n = 15). Nerve blocks were placed with the aid of a nerve stimulator using short bevelled, Teflon coated needles. The stimulation frequency was set at 2 Hz and the intensity of stimulating current, initially set at 1 mA, was gradually decreased to < or = 0.5 mA after each muscular twitch was observed. In the Single group, the anaesthetic solution was slowly injected after the first muscular twitch had been observed. In the Multiple group, 8 mL were injected at shoulder abduction, 6 mL were injected at arm flexion, and 6 mL at the extension of the arm. RESULTS: Placing the block required 5 min (4-8 min) in the Multiple group and 3 min (1-10 min) in the Single group (P = 0.001); however, total preoperative time (from skin disinfection to complete loss of pinprick sensation from C4 to C7 with inability to elevate the limb from the operating table) was shorter in the Multiple group (15 min; range 10-28 min) than in the Single group (23 min; range 14-60 min) (P = 0.03). Additional intravenous fentanyl supplementation was required in two patients of the Multiple group (13%) and eight patients of the Single group (53%) (P = 0.05). CONCLUSION: We conclude that using a multiple injection technique shortened the preparation time and improved the quality of interscalene brachial plexus anaesthesia performed with small volumes of ropivacaine 0.75%.     

三角肌运动反应用于小儿经肌间沟臂丛神经阻滞的临床观察

目的为三角肌运动反应作为在外周神经刺激器定位下小儿经肌间沟臂丛神经阻滞终点的临床应用提供参考。方法60例拟行上肢手术患儿,在外周神经刺激器定位下行经肌间沟臂丛神经阻滞,随机分为3组:A组(20例),三角肌运动反应终点组;B组(20例),肱二头肌运动反应终点组;C组(20例),三角肌和肱二头肌运动反应终点组。比较各组在刺激域电流、获得终点时间、合作患儿运动阻滞起效时间及神经阻滞效果的差异。结果组间刺激域电流、运动阻滞起效时间、神经阻滞效果差异无统计学意义(P>0.05);A、B组获得终点时间大于C组(P<0.05)。结论三角肌运动反应终点可以作为小儿经肌间沟臂丛神经阻滞穿刺针正确定位的标志。     

Transscalene brachial plexus block: a new posterolateral approach for brachial plexus block

Depending on the approach to the upper brachial plexus, severe complications have been reported. We describe a novel posterolateral approach for brachial plexus block which, from an anatomical and theoretical point of view, seems to offer advantages. Twenty-seven patients were scheduled to undergo elective major surgery of the upper arm or shoulder using this new transscalene brachial plexus block. The success rate was 85.2% for surgery. Two patients required additional analgesia with IV sufentanil. In two others, regional anesthesia was inadequate. The side effects of this technique included reversible recurrent laryngeal nerve blockade in two patients and a reversible Horner syndrome in one patient. Further studies are needed to compare the transscalene brachial plexus block with other approaches to the brachial plexus.     

经斜角肌臂丛神经阻滞：一种后侧入路臂丛神经阻滞的新方法

现有文献报道指出高位臂丛神经阻滞存在许多严重并发症。此文描述了一种从后侧方入路的臂丛神经阻滞新方法．该方法在解剖学上和理论上都有许多优点。27例拟行择期上臂或者肩部较大手术的患者接受了这种新的阻滞方法。成功率达到了85．2％。有两例患者加用静脉舒芬太尼镇痛，另有两例患者阻滞效果不佳。这种方法的副作用包括：两例患者出现了可逆的喉返神经阻滞，一例患者出现了可逆的Homer综合征。还需要进一步的研究将这种经斜角肌臂丛神经阻滞的方法与其他方法进行比较。     

One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography

Interscalene brachial plexus anesthesia for shoulder surgery routinely includes sensory anesthesia of the fourth and fifth cervical nerves. The authors reasoned that some degree of diaphragm paralysis should result from interscalene blocks that produce surgical C3-C5 sensory anesthesia. In this investigation, ultrasonography was used to study the incidence of ipsilateral hemidiaphragmatic paresis during routine interscalene block, as it is a practical, sensitive, and low-risk method for diagnosing hemidiaphragmatic function without radiation exposure. Thirteen healthy patients received interscalene blocks using a paresthesia technique with 34-52 mL 1.5% mepivacaine with added epinephrine and bicarbonate. All developed cervical sensory anesthesia. Data were collected before and 2, 5, and 10 min after injection, and, when possible (11 of 13 patients), at hourly intervals after surgery. Changes from normal to paradoxical motion of the ipsilateral hemidiaphragm were seen in all 13 patients during sniff and Mueller maneuvers within 5 min (in 11 of 13 patients at 2 min). Diaphragmatic motion returned to normal in 10 of 11 patients between 3 and 4 h after injection and in the remaining patient by the fifth hour after injection. Diaphragmatic paresis appears to be an inevitable consequence of interscalene brachial plexus block when providing anesthesia sufficient for shoulder surgery.     

Brachial plexus blocks: a review of approaches and techniques

PURPOSE: The purpose of this narrative review is to summarize the evidence derived from randomized controlled trials (RCTs) regarding established approaches and techniques for brachial plexus anesthesia. SOURCE: Using the MEDLINE (January 1966 to November 2006) and EMBASE (January 1980 to November 2006) databases, key words "brachial plexus", "nerve blocks", "interscalene", "cervical paravertebral", "suprascapular", "supraclavicular", "infraclavicular", "axillary", "brachial canal" and "humeral canal" were searched for full text articles pertaining to the evaluation of recognized approaches and techniques for brachial plexus anesthesia. The search was limited to RCTs involving human subjects and published in the English language. Seventy-six RCTs were identified. PRINCIPAL FINDINGS: Many of the published studies were underpowered and contained various methodological limitations. We found that, for shoulder and proximal humeral surgery, interscalene and cervical paravertebral approaches to the brachial plexus appear to provide equally effective surgical anesthesia. Intersternocleidomastoid supraclavicular blocks are not associated with improved postoperative analgesia despite eliciting more complete anesthesia of the brachial plexus. For surgery at or below the elbow, an infraclavicular block may result in decreased performance time and block-related pain while providing similar efficacy compared to (multiple-stimulation) axillary and brachial canal approaches. With respect to technique, it is unclear if nerve stimulation provides a more effective interscalene block than elicitation of paresthesiae. For supraclavicular blocks, nerve stimulation with a minimal threshold of 0.9 mA is recommended, whereas a double-stimulation technique is optimal for infraclavicular blocks. For the axillary approach, a triple-stimulation technique, involving injections of the musculocutaneous, median and radial nerves, is the most effective option. CONCLUSIONS: Published reports of RCTs provide evidence to formulate limited recommendations regarding optimal approaches and techniques for brachial plexus anesthesia. Further well-designed and meticulously executed RCTs are warranted, particularly in light of new techniques involving ultrasound or combining neurostimulation and echoguidance.     

Update in regional anesthesia for shoulder surgery

Recent advances in the application of regional anesthesia to the care of patients undergoing shoulder surgery are discussed. New techniques for the management of postoperative pain are highlighted, with an emphasis on interscalene patient-controlled analgesia and suprascapular block. New developments in the safety and effectiveness of brachial plexus block are presented. The technique of interscalene block used at our institution is discussed in detail. Intraoperative hypotension and bradycardia caused by activation of the Bezold-Jarisch reflex is considered. The ongoing debate regarding the use of paresthesia versus nerve-stimulator techniques is examined.     

超声引导下臂丛神经阻滞在上肢手术中的临床观察和经验

目的　研究超声引导臂丛神经阻滞相对于传统盲探下臂丛神经阻滞的优越性和实践经验。方法　选取我院采用超声引导臂丛神经阻滞上肢手术20例（超声引导组）,同时选择同期采用盲探异感法臂丛神经阻滞（盲探臂丛阻滞组）20例,比较两组患者各生理指标、生命体征变化、神经阻滞效应和并发症。结果　超声引导组患者的麻醉起效时间、镇痛维持时间、成功率均优于盲探臂丛阻滞组,两组比较差异有统计学意义（P<0.05）;盲探臂丛阻滞组的并发症高于超声引导组,但其差异没有统计学意义（P>0.05）。结论　超声引导下臂丛神经阻滞有助于使麻药准确注入至最佳位置,提高麻醉质量。     

Nerve localization techniques for interscalene brachial plexus blockade: a prospective, randomized comparison of mechanical paresthesia versus electrical stimulation

Postoperative neurologic symptoms (PONS) are relatively common after upper extremity orthopedic surgery performed under peripheral neural blockade. In this study, we prospectively compared the incidence of PONS after shoulder surgery under interscalene (IS) block using the electrical stimulation (ES) or mechanical paresthesia (MP) techniques of nerve localization. For patients randomized to the MP group, a 1-in, 23-g long-beveled needle was placed into the IS groove to elicit a paresthesia to the shoulder, arm, elbow, wrist, or hand. For patients randomized to the ES group, a 5-cm, 22-g short-beveled insulated needle was placed into the IS groove to elicit a motor response including flexion or extension of the elbow, wrist, or fingers or deltoid muscle stimulation at a current between 0.2 and 0.5 mA. Each IS block was performed with 50-60 mL of 1.5% mepivacaine containing 1:300,000 epinephrine and 0.1meq/L sodium bicarbonate. Two-hundred-eighteen patients were randomized between the two groups. One patient was lost to follow-up. Twenty-five patients (23%) in the ES group experienced paresthesia during needle insertion. The incidence of PONS using the ES technique was 10.1% (11/109), whereas the incidence with the MP technique was 9.3% (10/108) (not significant). The PONS lasted a median duration of 2 mo, and symptoms in all patients resolved within 12 mo. The success rate, onset time, and patient satisfaction were also comparable between groups. We conclude that the choice of nerve localization technique can be made based on the patient's and anesthesiologist's comfort and preferences and not on concern for the development of PONS.     

成人肌间沟臂丛神经阻滞运动反应终点的研究

目的研究胸大肌、三角肌运动反应作为外周神经刺激器(PNS)定位下成人经肌间沟臂丛神经阻滞终点的可行性。方法择期成人上肢手术240例,PNS定位下行经肌间沟臂丛神经阻滞,随机均分为四组:胸大肌运动反应终点组(A组)、三角肌运动反应终点组(B组)、肱二头肌运动反应终点组(C组)和胸大肌、三角肌或肱二头肌运动反应终点组(D组)。比较组间刺激域电流、获得终点时间、运动阻滞起效时间、各神经分支感觉阻滞起效时间、运动阻滞效果、各神经分支感觉阻滞效果及神经阻滞综合效果。结果D组获得终点时间短于A、B、C组(P<0.05),组间刺激域电流、运动阻滞起效时间、各神经分支感觉阻滞起效时间、运动阻滞效果、各神经分支感觉阻滞效果及神经阻滞综合效果差异无统计学意义。神经阻滞综合优良率90.8%。结论胸大肌、三角肌运动反应终点可作为PNS定位下成人经肌间沟臂丛神经阻滞穿刺针正确定位的满意、安全标志。     

Ultrasound-guided interscalene brachial plexus block in a child with acute upper respiratory infection

The brachial plexus is commonly blocked at the interscalene level for shoulder and proximal humeral surgery. There are only a few publications about the interscalene technique in pediatric patients for a peripheral nerve block. Ultrasound-guided peripheral nerve block has become increasingly more popular for pediatric patients because of high success rates and safety concerns. We used ultrasound-guided interscalene brachial plexus block in an 18-month-old child with an acute upper respiratory infection who had a supracondylar fracture of the humerus.     

Continuous shoulder analgesia via an indwelling axillary brachial plexus catheter

Continuous interscalene brachial plexus blockade can provide anesthesia and analgesia in the shoulder region. Difficulty accessing the interscalene space and premature displacement of interscalene catheters may preclude their use in certain situations. We present two case reports in which a catheter was advanced from the axilla along the brachial plexus sheath to the interscalene space to provide continuous cervicobrachial plexus analgesia. In the first case report, previous neck surgery made the anatomic landmarks for performing an interscalene block very difficult. An epidural catheter was advanced from the axillary brachial plexus sheath to the interscalene space under fluoroscopic guidance. This technique provided both intraoperative analgesia for shoulder surgery as well as 24-hour postoperative analgesia by an infusion of 0.125% bupivacaine. In the second case report, a catheter was inserted in a similar fashion from the axillary to the interscalene space to provide 14 days of continuous analgesia in the management of complex regional pain syndrome. We have found that this technique allows us to secure the catheter more easily than with the traditional interscalene approach and thus prevents premature dislodgment. This approach may be a suitable alternative when either an interscalene or an infraclavicular catheter may not be inserted.     

Low interscalene block provides reliable anesthesia for surgery at or about the elbow

Study ObjectiveTo determine whether interscalene brachial plexus block (ISB) provides adequate anesthesia for surgery on or about the elbow.Study DesignCase series.SettingOperating room of an academic teaching hospital.Patients78 patients scheduled for elective elbow surgery.InterventionsAll patients received an ISB using a low approach technique. A stimulating needle was inserted in the interscalene groove two cm above the clavicle. A volume of 35-45 mL of mepivacaine 1.5% or ropivacaine 0.5% was administered after obtaining a motor response of any component of the brachial plexus with a current intensity of 0.2-0.4 mA (0.1 msec).MeasurementsBlock success rate, defined as the ability to complete surgery without use of intraoperative opioids or general anesthesia, was assessed. Verbal rating scores for pain (0 = no pain, 10 = worst pain imaginable) were obtained in the recovery room.Main ResultsLow ISB resulted in successful surgical anesthesia in 75 (96%) of the study patients. Verbal rating scores were low (0-2) for all patients postoperatively.ConclusionsThe low interscalene block can be used to provide surgical anesthesia in the majority of patients having surgery on or about the elbow.