• Stephan Blumenthal, MD

        INTRODUCTION

The first brachial plexus blocks were performed by Halsted, in 1885, at the Roosevelt Hospital in New York City. Later Crile, in 1902, described an “open approach” to expose the plexus to the direct application of cocaine. At the time, however, the clinical applicability of this approach was limited because of the need for surgical exposure of the brachial plexus. Percutaneous access to the brachial plexus was described in the early 1900s. In 1925, Etienne¹ reported the successful blockade of the brachial plexus by inserting a needle at the level of the cricothyroid membrane, halfway between the lateral border of the sternocleidomastoid and the anterior border of the trapezius muscle after a single injection through the area around the scalene muscles. This approach is most likely the first clinically useful interscalene block technique.

        Different approaches were then tried until Winnie, in 1970,² described the percutaneous technique of injecting local anesthetic into the groove between the anterior and middle scalene muscles at the level of the cricoid cartilage. This approach was the first consistently effective and technically suitable technique, and it allowed wider applicability of interscalene brachial plexus block. Winnie’s approach was further modified, in line with numerous developments in regional anesthesia, by the placement of a perineural catheter, for example.³

Indications

Interscalene block is well suited for surgical procedures involving the shoulder, including the lateral two thirds of the clavicle, proximal humerus, and shoulder joint. Interscalene block can be used in the setting of arm or forearm surgery, but incomplete blockade of the inferior trunk often results in insufficient analgesia in the ulnar distribution. The patient’s positioning and comfort, the surgeon’s preferences, and the duration of surgery sometimes necessitate a combined general anesthesia. The indications for single-shot and interscalene catheter are summarized in Table 25-1.

    Skin infiltration of the posterior arthroscopic port insertion site with local anesthetics is often necessary despite a successful interscalene block.

Clinical Pearls

Contraindications

Contraindications for interscalene brachial plexus block are rare. Absolute contraindications include patient’s refusal, local infection, active bleeding in an anticoagulated patient, and proven allergy to local anesthetic. Relative contraindications include chronic obstructive airway disease, contralateral paresis of the phrenic or recurrent laryngeal nerves, and previous neurologic deficit of the involved arm. The risks and benefits of the chosen anesthetic technique should be discussed with the patient and the surgeon.

Anatomy

Understanding the relevant brachial plexus anatomy, ensuring precise needle location within the plexus diffusion space, and injection of appropriate volume and type of local anesthetic are fundamental for achieving high success rates with brachial plexus anesthesia. The plexus is formed by the ventral rami of the fifth to eighth cervical nerves and the greater part of the ventral ramus of the first thoracic nerve (Figure 25-1). In addition, small contributions may be made by the fourth cervical and the second thoracic nerves. The anatomy becomes complex because of the multiple connections to these ventral rami after they emerge from between the middle and the anterior scalene muscles until they end in the terminal nerves of the upper extremity. However, most of what happens to these roots on their way to becoming peripheral nerves is not clinically essential information to the anesthesiologist. Instead, broad concepts such as the spatial arrangement of the trunks (superior, middle, and inferior) and the muscular response elicited during electrostimulation can be helpful to clinicians (Table 25-2).

Figure 25-1. Organization of the brachial plexus.

        The brachial plexus supplies all the motor and most of the sensory functions of the shoulder except the cepha-lad cutaneous parts of the shoulder, which are innervated by the supraclavicular nerves originating from the lower part of the superficial cervical plexus (C3-4) (Figure 25-2). They supply sensation to the shoulder above the clavicle in addition to the first two intercostal spaces anteriorly. Furthermore, they supply sensation to the posterior cervical triangle and the upper thorax in this area as well as to the tip of the shoulder.⁶

        Only three nerves of the brachial plexus have cutaneous representation in the shoulder. The most proximal of these is the upper lateral brachial cutaneous nerve, a branch of the axillary nerve that innervates the lateral side of the shoulder and the skin overlying the deltoid muscle. The upper medial side of the arm is innervated by both the medial brachial cutaneous and the intercostobrachial cutaneous nerves. In the anterior portion of the arm over the biceps muscle, the skin is innervated by the medial antebrachial cutaneous nerve.⁶

        Apart from the cutaneous nerve supply to the shoulder, the innervation of the joint deserves special consideration. In general, a nerve crossing a joint gives branches that innervate it. Therefore, the nerves supplying the ligaments, capsule, and synovial membrane of the shoulder are fibers from the axillary, suprascapular, subscapular, and musculocutaneous nerves.^7,8 The relative contributions of these nerves are variable, and the supply from the musculocutaneus nerve may be very small or completely absent. Anteriorly, the axillary nerve and suprascapular nerve provide most of the nerve supply to the capsule and glenohumeral joint (Figure 25-3). In some instances, the musculocutaneous nerve may innervate the anterosuperior portion of the joint. In addition, the anterior capsule may be supplied by either the subscapular nerves or the posterior cord of the brachial plexus after piercing the subscapularis muscle. Superiorly, primary contribution is from two branches of the suprascapular nerve, one branch supplying the acromioclavicular joint and proceeding anteriorly as far as the coracoid process and coracoacromial ligament and the other branch reaching the posterior aspect of the joint. Other nerves contributing to this region of the joint are the axillary nerve and musculocutaneous nerve. Posteriorly, the main nerves are the suprascapular nerve in the upper region and the axillary nerve in the lower region (Figure 25-4).

Figure 25-2. The innervation of the skin over the shoulder and clavicle.

Figure 25-3. The innervation of the anterior portion of the shoulder. The axillary (1) and suprascapular (2) nerves form most of the nerve supply to the capsule and the glenohumeral joint.

Figure 25-4.The posterior innervation of the shoulder joint. The primary nerves are the suprascapular (1 ) and the axillary (2).

        Inferiorly, the anterior portion is primarily supplied by the axillary nerve, and the posterior portion is supplied by a combination of the axillary nerve and lower ramifications of the suprascapular nerve.

Clinical Pearls

Landmarks

The following surface anatomy landmarks are necessary for identifying the interscalene groove:

Figure 25-5. The lateral modified technique (Borgeat). The needle is inserted toward the plane of the interscalene space (dashed line) at an angle between 45 and 60 degrees. The needle is inserted approximately 0.5 cm under the level of the cricoid (C). SH, sternal head of the sternocleidomastoid muscle; CH, clavicular head of the sternocleidomastoid muscle. I, incisura jugularis sterni (sternal notch).

        These landmarks should always be marked with a pen (Figure 25-5).

Equipment for Single-Shot Blockade

Standard regional anesthesia equipment for a single-shot blockade consists of the following items (Figure 25-6).

        Marking pen, ruler

        Sterile gloves

        Peripheral nerve stimulator, surface electrode

        Disinfection solution and sterile gauze packs

        2-to 5-cm, short-bevel, 22-gauge insulated stimulating needle

        Syringes with local anesthetic

Figure 25-6. Equipment for single-injection interscalene block.

Figure 25-7. Equipment for continuous interscalene block.

Equipment for Continuous Blockade

Standard regional anesthesia equipment for a continuous nerve block consists of the following items (Figure 25-7).

        Marking pen, ruler

        Peripheral nerve stimulator, surface electrode

        Disinfection solution, sterile gauze packs

        Sterile transparent drapes

        Syringes with local anesthetic for skin infiltration and block injection

        25-mm, 25-gauge needle for skin infiltration at puncture point and for tunneling

        A set with stimulating needle for continuous nerve block and catheter

        Adhesive transparent tapes for securing the catheter

        Sterile gloves (cap, mask, and gown are optional)

         APPROACHES TO & TECHNIQUES FOR BRACHIAL PLEXUS BLOCK AT THE LEVEL OF THE NECK

Several approaches for interscalene block are known; with all modern techniques, the use of a nerve stimulator is recommended to localize the brachial plexus. The common techniques are those ofWinnie, Pippa, modified lateral techniques (Meier and Borgeat), and the low interscalene approach.

Classic Technique (Winnie)

The classic approach ofWinnie² is performed at the level of the sixth cervical vertebra. Although Winnie originally used a paresthesia technique, most clinicians nowadays use a nerve stimulator technique.

Related posts:

Regional Anesthesia in the Patient with Preexisting Neurologic Disease. The History of Local Anesthesia. Stimulating Catheters. Ultrasound-Assisted Nerve Blocks in Adults. Cutaneous Blocks for the Upper Extremity. Cervical Plexus Block.