0082: Live Scanning Workshop: Brachial Plexus and Upper Limb Nerves

Abstract

Ultrasound imaging of the brachial plexus is fast becoming the imaging modality of choice when “locally” blocking the upper arm for rotator cuff - shoulder surgery. As the brachial plexus innervates the upper extremity, and is relatively superficial , ultrasound can guide the anesthetist straight to the nerve bundle (brachial plexus) to be “blocked”. This block is termed an interscalene block and is the most proximal approach to the Brachial Plexus and the most suitable for proximal procedures on the arm and shoulder. The block is a paravertebral approach at the level of the cervical roots in the neck and can provide both brachial and cervical nerve blocks. The anterior primary roots of the cervical nerves (C5,6,7,8 T1) course anterolaterally and inferiorly to lie between the anterior scalene and the middle scalene muscles which, arise from the anterior and posterior tubercules of the cervical vertebrae. The prevertebral fascia covers both the scalene muscles fusing laterally to enclose the brachial plexus in a fascia sheath. This is easily identified with ultrasound as it presents as a bright echogenic structure (sheath) and a “bunch of grapes” image as the nerve. Between the scalene muscles, these nerve roots unite to from three trunks, which emerge from the interscalene groove to lie cephaloposterior to the subclavian artery as it courses along the upper surface of the first rib. Once identified the needle (23G butterfly) is introduced to the region in the transverse plane. The needle must be perpendicular to the ultrasound probe to demonstrate the tip and confirm the correct positioning and angle required to anaethetise the brachial plexus.