BLOCK AT A GLANCE
Block of the branches of the cervical plexus (C2-C4).
Indications: Anesthesia and/or analgesia for carotid surgery, thyroid and superficial neck surgery, treatment of cervical muscle spasm, and analgesia for clavicle fracture
Goal: Local anesthetic (LA) spread around the branches of the cervical plexus
Local anesthetic volume: 5 to 8 mL
The cervical plexus block is a well-established technique that traditionally has been performed using external anatomical landmarks before the introduction of ultrasound (US).
Although the terminology and description of the cervical fasciae can be inconsistent, there are three common approaches to block the cervical plexus (Figure 12-1).
Deep injection technique: LA can be deposited at the C2-C4 paravertebral space, deep to the prevertebral fascia, to block the entire plexus. Note: This technique is more accurately termed a paravertebral block of spinal nerves C2-C4, rather than “deep cervical plexus.”
Intermediate technique: LA is injected at the level of the C4 transverse process, between the prevertebral fascia and the investing layer of the deep cervical fascia, to block the superficial branches of the plexus.
Superficial technique: At the level of C6, the LA is injected subcutaneously and superficially to the deep cervical fascia to block all or specific cutaneous branches.
Cross-sectional anatomy of the cervical plexus at the level of C4 and at the level of C6.
A deep injection technique carries a higher risk of injection into the spinal canal or vertebral artery, or blocking the cranial nerves. Therefore, in this chapter, we describe the intermediate and superficial techniques, which are safer and equally effective for most indications. There are few, if any, indications for a cervical plexus block deep to the prevertebral fascia. Moreover, bilateral deep injection techniques are not recommended because of potential respiratory failure and airway obstruction due to a bilateral block of the vagus, hypoglossal, and phrenic nerves.
The risks include paroxysmal cough, recurrent or phrenic nerve block, dysphagia, dysphonia, Horner syndrome, and stellate ganglion block.
The cervical plexus originates from the anterior rami of C1-C4. The anterior ramus of C1 (the suboccipital nerve) is a motor nerve that is not blocked as part of any described cervical plexus block technique. Thus, a cervical plexus block is best defined as a block of the anterior rami of C2 through C4. The anterior branches of C1-C4 of the cervical plexus combine into three loops from which the deep and superficial branches arise (Figure 12-2). The cervical plexus is connected to the hypoglossal, glossopharyngeal, and vagus nerves, as well as the sympathetic trunk, contributing to the innervation of muscles and structures relevant to airway control, respiratory function, phonation, and swallowing.