Ultrasound-guided musculocutaneous nerve block: a description of a novel technique

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.

A NIR Dye for Development of Peripheral Nerve Targeted Probes

Current imaging modalities lack the ability to quickly assess and classify nerve injury for predicting favourable versus unfavourable healing outcomes, which could minimize episodes of chronic pain and loss of function by allowing for early intervention. Thus, the development of a technique to noninvasively assess peripheral nerve damage is of critical importance. While the development of nerve specific near infrared (NIR) molecular probes capable of such diagnostics constitutes our long term goal, initial studies to identify a NIR dye for constructing such a probe are required. We have evaluated the properties of a novel highly hydrophilic and functionalizable polymethine dye, and its more hydrophobic analogue indocyanine green, within the sciatic nerve of rats following intra-nerve injection. The reporting ability of both dyes at critical depths for nerve imaging, the importance of hydrophilicity on dye transport through nervous tissue, and their toxicity - or lack thereof - to the neural environment have been evaluated. The results suggest that the novel NIR dye is an appropriate fluorescent reporter for use in designing nerve-specific optical molecular probes for non-invasive diagnosis and classification of nerve injury.

Upper extremity regional anesthesia: essentials of our current understanding, 2008

Brachial plexus blockade is the cornerstone of the peripheral nerve regional anesthesia practice of most anesthesiologists. As part of the American Society of Regional Anesthesia and Pain Medicine's commitment to providing intensive evidence-based education related to regional anesthesia and analgesia, this article is a complete update of our 2002 comprehensive review of upper extremity anesthesia. The text of the review focuses on (1) pertinent anatomy, (2) approaches to the brachial plexus and techniques that optimize block quality, (4) local anesthetic and adjuvant pharmacology, (5) complications, (6) perioperative issues, and (6) challenges for future research.

Ultrasound guidance in regional anesthesia: state of the art review through challenging clinical scenarios

Ultrasound guided regional anesthesia (UGRA) for peripheral nerve blockade is becoming increasingly popular. The advantage of ultrasound technology is that it affords the anesthesiologist the real time ability to visualize neural structures, needle advancement, and local anesthetic spread. Recent data suggest that UGRA generates improved success rates and reductions in performance times in comparison to traditional approaches. Further, the use of ultrasound technology in peripheral nerve blocks has provided insight into needle-nerve interactions, revealing distinct limitations of nerve stimulator techniques. Given that UGRA requires a unique set of skills, formal standards and guidelines are currently being developed by leadership societies in order to foster education and training. This review article, in a case vignette format, highlights important techniques, concepts, and limitations regarding the use of ultrasound to facilitate regional anesthesia. Clinically relevant aspects of ultrasound physics are also discussed.

Ultrasound guidance improves the success rate of a perivascular axillary plexus block

BACKGROUND

Traditional approaches to performing brachial plexus blocks via the axillary approach have varying success rates. The main objective of this study was to evaluate if a specific technique of ultrasound guidance could improve the success of axillary blocks in comparison to a two injection transarterial technique.

METHODS

Fifty-six ASA physical status I-III patients presenting for elective hand surgery were prospectively randomized to receive an axillary block performed by either a transarterial technique (Group TA) or an ultrasound-guided perivascular approach (Group US). Both groups received a total of 30 ml of 1.5% lidocaine (225 mg) with 5 microg/ml epinephrine. Patients were then evaluated for block onset in specific nerve distributions and whether or not the block acted as a surgical anesthetic.

RESULTS

Group TA sustained more failures defined as conversion to general anesthesia or the inability to localize the artery [Group TA eight patients (29%) vs. Group US in which 0 patients required conversion to general anesthesia (0%) P < 0.01]. Group US demonstrated a reduction in performance times vs. Group TA (7.9 +/- 3.9 min vs. 11.1 +/- 5.7 min, P < 0.05). By 30 min post-injection, there were no significant differences between groups TA and US in terms of the proportion of patients demonstrating a complete motor or sensory loss.

CONCLUSION

Ultrasonographic guidance improves the overall success rate of axillary blocks in comparison to a transarterial technique.