Variant location of the musculocutaneous nerve during axillary nerve block

Retrospective Single-Center Comparative Analysis of Ultrasound-Guided Versus Non-ultrasound-Guided Nerve Blocks in Extremity Surgeries

OBJECTIVES

Although ultrasound-guided peripheral nerve blocks have become increasingly popular, it is arguable at present whether ultrasound guidance is a necessary tool for peripheral nerve blocks. The purpose of this study was to assess the significance of ultrasound-guided peripheral nerve blocks in reducing complications.

METHODS

From January 2013 to January 2019, 17,823 patients who underwent peripheral nerve blocks with/without ultrasound guidance were reviewed, recording data on their age, sex, height, weight, American Society of Anesthesiologists, block type, operation type, operation duration, and complications. The patients were divided into 2 groups: 9372 cases with ultrasound guidance (US Group) and 8451 cases without ultrasound guidance (No-US Group). To control selection bias, a total of 16,236 patients were finally included in this study after 1:1 propensity score matching, including 8118 cases in the US Group and 8118 cases in the No-US Group. Outcome measures included local anesthetic systemic toxicity (LAST), nerve injury, incomplete block anesthesia (IBA), local hematoma, and infection at the block site.

RESULTS

Baseline characteristics of patients were similar between the two groups (P >.05, respectively). Our study revealed that the incidence of infection was similar between the two groups (P >.05). However, the incidences of LAST, nerve injury, IBA, and local hematoma in the US Group were significantly lower than those in the No-US Group (P <.05, respectively).

CONCLUSIONS

Our findings suggest that ultrasound-guided peripheral nerve blocks are associated with fewer complications and higher success rates, compared with the paresthesia approach.

Updated Retrospective Single-Center Comparative Analysis of Peripheral Nerve Block Complications Using Landmark Peripheral Nerve Stimulation Versus Ultrasound Guidance as a Primary Means of Nerve Localization

OBJECTIVES

The purpose of this study was to perform an updated analysis of complications associated with upper and lower extremity peripheral nerve blocks (PNBs) performed with ultrasound (US) guidance versus the landmark approach.

METHODS

We conducted a single-center retrospective cohort analysis to compare the incidence of PNB complications between the techniques. The primary outcome was local anesthetic systemic toxicity (LAST), whereas the secondary outcomes included short- and long-term nerve injuries. The current query included cases performed between 2012 and 2015. A combined analysis included data extending to 2006. The Statistical examination relied on the χ² test.

RESULTS

During this 4-year period, we performed 7789 US-guided and 498 landmark-guided blocks with no statistically significant difference in the incidence of nerve injury or LAST between the groups. Our 10-year analysis, however, revealed a significant increase (P < .01) in the rate of LAST with the landmark technique: 7 of 5932 versus 0 of 16,858 cases. The combined data also revealed a significant increase (P < .01) in short-term injuries associated with the landmark approach (30 of 5932 versus 33 of 16,858) but no significant difference in the incidence of long-term injuries.

CONCLUSIONS

Our analysis supports a conclusion that the use of US guidance during PNBs leads to a significant reduction in the incidence of LAST, adding to growing evidence from similar investigations. The impact of US on the incidence of nerve injuries remains unclear, considering that the nature of transient deficits is thought to be multifactorial, and the frequency of lasting injuries did not differ significantly in this study.

Evaluation of the relationship between the topographical anatomy in the axillary region of the brachial plexus and the body mass index

To investigate the topographic anatomy of the median, musculocutaneous, radial and ulnar nerves with respect to the axillary artery and to seek whether these configurations are associated with baseline descriptive data including age, gender, and body-mass index. This cross-sectional trial was carried out on 199 patients (85 women, 114 men; average age: 46.78 ± 15.45 years) in the department of anaesthesiology and reanimation of a tertiary care center. Topographic anatomy of the median, musculocutaneous, radial and ulnar nerves was assessed with ultrasonography. Localization of these nerves with respect to the axillary artery was marked on the map demonstrating 16 zones around the axillary artery. Frequencies of localizations of every nerve in these zones were recorded, and the correlation of these locations with descriptive data including age, gender and BMI was investigated. There was no difference between women and men for the distribution of the median (p = 0.74), ulnar (p = 0.35) and radial (p = 0.64) nerves. However, the musculocutaneous nerve was more commonly located in Zone A13 in men compared to women (p = 0.02). The localization of the median (p = 0.85), ulnar (p = 0.27) and radial (p = 0.88) nerves did not differ remarkably between patients with BMI < 25 kg/m² and patients with BMI ≥ 25 kg/m². Notably, the musculocutaneous nerve was more often determined in Zone A10 in cases with BMI ≥ 25 kg/m² (p = 0.001). Our results imply that the alignment of the musculocutaneous nerve may vary in men and overweight people. This fact must be considered by the anaesthetist before planning the axillary block of brachial plexus. All these informations may enlighten the planning stages of the brachial plexus blockade.

Importance of the Upper Extremity Position for a Safe and Effective Axillary Block: a Comparative Study

OBJECTIVE

Our aim was to determine the ideal position of upper extremities during ultrasonography guidance for axillary block. The position that provides the shortest distance between the median and musculocutaneous nerves was assumed to be the most appropriate position for axillary block.

METHODS

In this cross-sectional study, 120 (45 female and 75 male) patients were placed in a position with a shoulder at 90° / elbow 90° (position 1) and a shoulder 90° / elbow 0° (position 2). The intersection point of the biceps brachii muscle with the lower border of the pectoralis major muscle is defined as the proximal level (P). Distal level (D) is reffered as 5 cm below the proximal level. In the positions described above, the distance between median and musculocutaneous nerves was measured proximal (positions 1P and 2P) and distal levels (positions 1D and 2D). It was investigated whether these measurements differed between the groups and whether the body mass index or the gender.

RESULTS

The shortest mean distance (10.24±3.95 mm) between the two nerves was determined when the shoulder position 90°/elbow position 0° at the distal level (1D) and the longest mean distance (13.41±4.26 mm) was determined when shoulder position 90°/elbow position 90° at the proximal level (2P). In all four cases, there was no difference in the results between men and women. There was no relationship between the measurement results and the body mass indexes and age of the patients.

CONCLUSION

Appropriate positioning of the upper extremities is important for achieving optimal position during axillary block. Thereby, the procedure can be safely and effectively performed with lesser amounts of local anaesthetic solution and a decreased number of manoeuvres with needle during infiltration.

Variations in brachial plexus with respect to concomitant accompanying aberrant arm arteries

INTRODUCTION

Variations in the brachial plexus are the rule rather than the exception. This fact is of special interest for the anesthetist when planning axillary block of brachial plexus.

MATERIAL AND METHODS

167 cadaver arms were evaluated for variations in brachial plexus, with focus on the cords of the plexus, the loop of the median nerve, and the course of the median, musculocutaneous, ulnar, axillary and radial nerves. In addition, concomitant arterial variations were recorded.

RESULTS

In 167 arms, variations were detected in 60 cases (36%). With 46 arms (28%) most variations concern the median nerve, followed by 13 cases (8%) which involved the musculocutaneous nerve. Ulnar, axillary and radial nerve variations were rare, amounting to 1.2% for each nerve. In median nerve conditions with a shifted loop of median nerve (12%), a hidden position of the loop or a hidden course of the beginning median nerve (8%) and a doubled loop of median nerve (17%) were observed. In musculocutaneous nerve conditions with a non-perforated coracobrachialis (1.8%), a doubled origin of the nerve (1.2%) and a giving back of branches to the median nerve (1.8%) were noted. Variations in ulnar, axillary and radial nerves concerned lower than normal diameters.

CONCLUSIONS

It must be stressed that cases which showed a hidden position or a doubled expression of the loop of the median nerve, a hidden course of its beginning and variable interconnections between musculocutaneous and median nerves are of special interest for anesthetists and surgeons. Hence, it is important to note that variations of arm arteries can be associated with brachial plexus variations. For example, a common trunk of axillary artery followed by a hidden loop and course of the median nerve may result in incomplete axillary block of brachial plexus.

Ultrasound-Guided Musculocutaneous Nerve Block in Postherpetic Neuralgia

Postherpetic neuralgia is a common and challenging complication of herpes zoster infection, particularly in older people. In recent decades, first-line treatments, including oral or topical medication, have become well established. However, few studies have reported the efficacy of interventional procedures for the treatment of postherpetic neuralgia. Here, the authors present a case of intractable postherpetic neuralgia treated with musculocutaneous peripheral nerve block under ultrasound guidance. Symptoms remained controlled at 1 mo follow-up. Ultrasound can be readily applied to improve the accuracy and efficiency of peripheral nerve block as it is currently widely used to evaluate the musculoskeletal system in clinical settings.

Ultrasound-guided anterior axilla musculocutaneous nerve block

PURPOSE

This paper presents a technique of ultrasound-guided localisation and block of the musculocutaneous nerve through the anterior wall of the axilla.

MATERIALS AND METHODS

Twenty patients (7 males and 13 females; mean age, 35 years) had axillary nerve block for upper extremity trauma. With the arm adducted, the ultrasound probe was positioned on the anterior axillary wall; the axillary artery, coracobrachialis and pectoralis major muscles and lateral cord of brachial plexus were visualised in cross section. With continuous imaging of the axillary artery in cross section, the ultrasound probe was slowly moved towards the biceps muscle until the musculocutaneous nerve appeared crossing the coracobrachialis muscle. After ultrasound localisation of the musculocutaneous nerve, the arm was abducted and externally rotated, and the nerve was identified with nerve stimulation and blocked. The quality of sensory and motor nerve block, as well as of ultrasound imaging were evaluated.

RESULTS

Ultrasound-guided block of the musculocutaneous nerve was excellent and complete in 18 of the 20 patients. In two patients, the musculocutaneous nerve was fused with the median nerve and the nerve block was repeated successfully with the same technique. The quality of ultrasound imaging was excellent in all patients. No patient experienced pain or tourniquet discomfort during surgery, or any other nerve block-related complication.

CONCLUSION

The anterior axillary ultrasound view provides for complete nerve block and imaging of the entire course of the musculocutaneous nerve and its relations with adjacent structures with excellent quality.

[Absence of the musculocutaneous nerve and its distribution from median nerve: About two cases and literature review]

Musculocutaneous nerve arises mostly from the lateral cord of brachial plexus. Nevertheless, variations have been reported and, among them: the total absence of musculocutaneous nerve (from 1.4 to 15%), the absence of its passage through the coracobrachial muscle, its variable level of penetration as measured from the tip of the coracoid process, and its communicating branches with the median nerve. We report two cases of unilateral musculocutaneous nerve absence in a 66-year-old male and a 95-year-old female cadavers, on the right and the left side, respectively. The nerve fibers normally coming from musculocutaneous nerve emerged from the median nerve. The knowledge of this anatomical variation is important specially when performing plexus bloc or Latarjet's procedure.

Ultrasound-guided peripheral and truncal blocks in pediatric patients

Ultrasound has added a feather in the cap of the anesthesiologists as real-time nerve localization and drug deposition around the nerve structure under real-time guidance is now a reality, as the saying “seeing is believing” has been proven true with the advent of ultrasound in anesthesia. Pediatric patients are a unique group regarding their anatomical and physiological features in comparison with adults; regional blocks in adults with the anatomical landmark and surface marking are almost uniform across the adult population. The landmark technique in pediatric patients is not reliable in all patients due to the variability in the age and size; the advent of ultrasound in assisting nerve localization has changed the way regional blocks are achieved in children and the range of blocks performed on adults can now be performed on pediatric patients; with advances in the technology and dexterity of ultrasound equipment, the chances of success of blocks has increased with a smaller dose of the local anesthetic in comparison to the traditional methods. Anesthesiologists are now able to perform blocks with more accuracy and avoid complications like intravascular injection and injury to the pleura and peritoneum during routine practice with the assistance of high-frequency transducers and top of the range portable ultrasound machines; catheters can be inserted to provide a continuous analgesia in the postoperative period. This review article describes the common peripheral blocks in pediatric patients; the readers are encouraged to gain experience by attending workshops, hands-on practice under supervision, and conduct random controlled trials pertaining to ultrasound-guided blocks in the pediatric age group. The recent literature is encouraging and further research is promising; a wide range of blocks being described in detail by many prominent experts from all over the world.

Is the musculocutaneous nerve really in the coracobrachialis muscle when performing an axillary block? An ultrasound study

BACKGROUND

In reference textbooks describing axillary block, the ulnar, radial, and median nerves are located in a common sheath surrounding the axillary artery. In contrast, the musculocutaneous nerve is described as lying outside this sheath in the coracobrachialis muscle. In a recent case report of ultrasound-guided axillary block, the musculocutaneous nerve was joined to the median nerve outside this muscle. Our study evaluated the prevalence of atypical musculocutaneous nerve localizations during axillary block.

METHODS

All patients undergoing ultrasound-guided axillary block were included from December 2006 to December 2008. Before needle insertion, musculocutaneous, median, ulnar, and radial nerves were localized using ultrasound. Nerve stimulation confirmed atypical nerve localization. After injection of local anesthetics, musculocutaneous and median nerve anatomical relationships were observed.

RESULTS

The musculocutaneous nerve was outside the coracobrachialis muscle in 83 of the 387 analyzed blocks (22%). It was near the axillary artery in 22 cases (6%). The musculocutaneous and median nerves appeared as a common neural structure in 61 cases (16%). After local anesthetic injection, a common trunk persisted in 16 of 61 cases (26%), musculocutaneous and median nerves separated in 37 cases (61%), and 2 roots of the median nerve appeared (with or without a separated musculocutaneous nerve) in 6 cases (10%). Two cases (3%) remained undefined. Ulnar nerve location of the 83 patients with atypical musculocutaneous nerve position differed from the ones with a classical musculocutaneous nerve localization.

CONCLUSIONS

During axillary block, the musculocutaneous nerve is outside the coracobrachialis muscle in 1 of 5 patients. This atypical location should be considered during performance of axillary blockade to avoid repeated IM puncture.

Ultrasound-guided nerve blocks: efficacy and safety

The introduction of affordable, portable and high-resolution ultrasound machines has rejuvenated interest in regional anaesthesia. The inherent benefits of direct visualisation of nerves and surrounding anatomy, continual observation of the needle tip and spread of local anaesthetic make ultrasound-guided regional anaesthesia highly appealing. However, in the cost-conscious health-care setting and to convince sceptics, there also needs to be evidence of increased benefits and reduced complications. Ultrasound is a rapidly developing area of technology and some of the newer modalities are discussed. This article focusses on the recent growing evidence to support the benefits of its use in nerve and plexus blocks. Common complications of nerve blocks can be avoided with ultrasound but have still been reported. Anatomical variants have been demonstrated by ultrasound and it has proved to be useful in performing regional anaesthesia in difficult situations or where peripheral nerve stimulation is unsuccessful or inappropriate.

Intersegmental origin of the axillary artery and accompanying variation in the brachial plexus

The wide anatomical variation of the brachial plexus and the axillary artery has been thoroughly explored in previous studies. However, there has been little information reported on the variation in the relationship between the brachial plexus and the axillary artery. The principal feature of this relationship is the passage of the axillary artery through the loop of the median nerve, which occurs in normal arteries derived from the seventh intersegmental artery. In this study, we analyzed the abnormal position and course of the axillary artery related to the brachial plexus in 607 axillae of 306 cadavers. We found 12 unusual axillary arteries that did not pass through the median loop. Eleven arteries were determined to be ninth intersegmental arteries and one as the sixth intersegmental artery. All ninth intersegmental arteries ran caudally to the brachial plexus. In six cases of this type, abnormal connections interfering with the normal arterial position were observed in the brachial plexus. In another five cases of this type, the lateral and medial cords merged and the axillary artery passed anteromedial to the plexus. The sixth intersegmental axillary artery pierced the musculocutaneous nerve which is from the unified lateral and medial cords. This study discussed the how the anomalous structure of the brachial plexus could involve the deterioration of the course of the axillary artery.

Ultrasound and neurostimulation-guided axillary brachial plexus block for resection of a hemodialysis fistula aneurysm

An ASA III patient presenting with a voluminous hemodialysis fistula aneurysm at the elbow was scheduled for its resection. Axillary brachial plexus block was performed under ultrasound and neurostimulation guidance. Despite unexpected nerve positions in relation to pathological vascular anatomy, this combined approach resulted in an adequate block with a low volume of local anesthetic, without obvious vascular puncture or intraneural injection.