CERVICAL PLEXUS BLOCK AT A GLANCE
Indications: carotid endarterectomy, superficial neck surgery (Figure 32A–1)
Transducer position: transverse over the midpoint of the sternocleidomastoid muscle (posterior border)
Goal: local anesthetic spread around the superficial cervical plexus or deep to the sternocleidomastoid muscle
Local anesthetic: 5–15 mL
Expected sensory distribution of cervical plexus blockade.
The goal of the ultrasound (US)-guided technique of superficial cervical plexus block is to deposit local anesthetic within the vicinity of the sensory branches of the nerve roots C2, C3, and C4 (Figures 32A–2 and 32A–3). Advantages over the landmark-based technique include the ability to visualize the spread of local anesthetic in the correct plane, which therefore increases the success rate, and to avoid a needle insertion that is too deep and the inadvertent puncture of neighboring structures.
Both US-guided superficial and deep cervical plexus blocks have been well described.1-8 The deep cervical plexus block is an advanced block with a risk of potentially serious complications, such as intrathecal injection or injection into the vertebral artery. For this reason, we will focus primarily on the superficial cervical plexus block technique. It is simpler, safer, and, for most indications, it is equally as suitable as the deep cervical plexus block. An understanding of the fascial planes of the neck and the location of each of these blocks is necessary (see Figure 32A–2). For the superficial cervical plexus block, local anesthetic is injected superficially to the deep cervical fascia. For the superficial (intermediate) cervical plexus block, the injection is made between the investing layer of the deep cervical fascia and the prevertebral fascia, whereas for the deep cervical plexus block, local anesthetic is deposited deep to the prevertebral fascia.
Site of injection of local anesthetic for superficial, intermediate, and deep cervical plexus blocks.
Anatomy of the deep cervical plexus and its main branches and anastomoses.
The sternocleidomastoid muscle (SCM) forms a “roof” over the nerves of the superficial cervical plexus (C2–4) (see Figure 32A–2). The roots combine to form the four terminal branches (the lesser occipital, greater auricular, transverse cervical, and supraclavicular nerves) and emerge from behind the posterior border of the SCM (Figures 32A–3, 32A–4, and 32A–5). The plexus can be visualized as a small collection of hypoechoic nodules (honeycomb appearance or hypoechoic [dark] oval structures) immediately deep or lateral to the posterior border of the SCM (see Figure 32A–5), but this is not always apparent. Occasionally, the greater auricular nerve is visualized ...