Interscalene brachial plexus block
An interscalene brachial plexus block is indicated for procedures involving the shoulder and upper arm.
Ultrasound-guided nerve blocks (UGNBs) entered the literature in 1989, when Ting et al3 detailed their success with axillary nerve blocks in 10 patients.
- proximal humerus fracture
- glenohumeral dislocation
- frozen shoulder manipulation
- deltoid abscess aspiration5
Local infection, severe coagulopathy, local anesthetic allergy, and patient refusal
Full neurovascular exam should be performed and recorded5, and consent should be obtained. A short-acting benzodiazepine or opioid may be used to reduce procedural anxiety.
Positioning/room set up
IV access should be obtained, and the patient should be placed on the cardiac monitor. The ultrasound machine should be optimally positioned for ergonomic visualization during the procedure1, typically on the opposite side of the bed. The patient is positioned supine with their head rotated 45 degrees to the contralateral side.
Two 20-cc syringes, 20-g 3.5-inch blunt-tip block needles, IV extension tubing, Two 10-cc normal saline flushes, 18-g needle, 30-g needle, transparent dressing, alcohol swabs, chlorhexidine, body marking pen.
Anatomy is first defined with a high frequency linear probe, placed in a transverse orientation along the course of the anterior and middle scalenes, roughly around the level of the C6 vertebral body. One may begin using the internal jugular vein and common carotid as sonographic landmarks.
The transducer should be moved laterally, to the edge of the sternocleidomastoid. The sternocleidomastoid's clavicular head may be identified superficially, as well as the deeper anterior and middle scalenes. Three hypoechoic structures may then be visualized in the interscalene groove, representing the C5-C7 roots.
Place skin wheal at site of insertion with 30-g needle. Using an in-plane technique with the probe marker directed toward patient midline, the needle is inserted parallel to the ultrasound beam. The needle is advanced through the middle scalene muscle under real-time guidance until just short of the interscalene groove. The needle is then advanced into the groove with hydrodissection, and circumferential spread of local anesthetic should be achieved, requiring roughly 10-20cc lidocaine (higher volume block).
Repeat neurovascular exam should be immediately performed. Type of block, anesthetic, and time procedure was performed should be enumerated in the medical record. Limb should be immobilized and patient educated on follow-up precautions.
- hemidiaphragmatic paresis
- horner’s syndrome
- recurrent laryngeal nerve involvement
- vertebral artery injection
- epidural injection
Sensorimotor function in the proximal upper arm and shoulder affected more profoundly than distal upper extremity. C8 and T1 dermatomes often retain sensation.