The interscalene block targets the brachial plexus at the level of the trunks or roots and is used for surgeries performed on the shoulder and lateral aspect of the upper arm. Innervation of the shoulder and many of the nerves affected by an interscalene nerve blockade are identified in Table 20.6.
Indications include primary anesthesia and/or postoperative pain management with or without a continuous catheter for shoulder and shoulder joint, lateral two-third of clavicle, and proximal humerus surgeries. Arm and forearm surgeries with an interscalene block do not often provide adequate coverage of the ulnar nerve distribution (C8-T1) and are therefore not completely useful for surgeries of the lower arm, wrist, or hand. Lack of appropriate blockade of the ulnar nerve distribution subsequent to an interscalene block may be circumvented by
Axillary |
In fradavicular |
Supraclavicular |
and |
Interscalene |
Brandies |
Cords |
Divisions |
Trunks |
Roots |
C4 | ||||
Musculocutaneous |
Lateral |
Anterior Posterior |
Superior |
C5 |
Axillary |
C6 | |||
Median |
Posterior |
Anterior Posterior |
Middle |
C7 |
Radial |
Inferior |
C8 | ||
Ulnar |
Medial |
Anterior Posterior |
T1 |
Figure 20.2 (Continued)
Table 20.6 Innervation of the shoulder and interscalene nerve blockade.
Nerve
Brachial plexus
Upper lateral brachial cutaneous (from the axillary n.) Intercostobrachial
Supraclavicular (C3, C4)
Subclavius
Dorsal scapular
Long thoracic Suprascapular
Axillary, suprascapular, subscapular
Motor of the shoulder
Sensory of the shoulder
All except cephalad cutaneous parts innervated by supraclavicular n. (C3-C4) Lateral side of shoulder and skin overlying the deltoid Anterior and medial skin of shoulder and posterior upper arm
Skin over upper deltoid/shoulder
Joint of the shoulder
Subclavius m. Rhomboid and levator scapulae m. Serratus anterior m. Supraspinatus and infraspinatus m. Deltoid and teres minor m.
Acromioclavicular joint Sternoclavicular joint
Skin of the shoulder over inferior Shoulder joint deltoid using larger local anesthetic volumes or supplemental blockade of the ulnar nerve at a more distal location of the upper extremity.
Arrange sterile towels, sterile gloves, gauze pads, marking pen, antiseptic solution, peripheral nerve stimulator, syringes, and needles for local infiltration and nerve block placement.
Dose
20-40 ml syringes of local anesthetic. Needles
25 g 1.5 in. needle for skin infiltration and 22 g 3 or 5 cm short bevel insulated stimulation needle.
Agents
3% chloroprocaine, 2% lidocaine, 0.5% ropivacaine, 0.5% bupivacaine.
Landmarks include posterior and lateral borders of the sternal and clavicular heads of sternocleidomastoid m., C6 tubercle, interscalene groove formed by the middle and anterior scalene m., upper border of cricoid cartilage, and clavicle (Fig. 20.3).
The patient should be positioned supine with their head turned away from the side to be blocked. The arms are to remain relaxed at the patient's side. A line drawn laterally from
Figure 20.3 Surface landmarks for the classical interscalene approach to the brachial plexus. (a) Sternal notch, (b) external jugular vein, and c sternocleidomastoid muscle. Line #1 identifies the clavicle. Dashed line #2 indicates the C6 vertebral process and is the line/path along which to follow in search of the appropriate muscle response. X marks the needle entry site.
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