• Tony Tsai, MD
• Ad mir Hadzic, MD

I.	INTRODUCTION
II.	INDICATIONS & CONTRAINDICATIONS
III.	FUNCTIONAL ANATOMY OF DEEP CERVICAL PLEXUS BLOCKADE Anatomic Landmarks Choice of Local Anesthetic Equipment Technique
IV.	BLOCK DYNAMICS & PERIOPERATIVE MANAGEMENT
V.	FUNCTIONAL ANATOMY OF SUPERFICIAL CERVICAL PLEXUS BLOCKADE Anatomic Landmarks Choice of Local Anesthetic Equipment Technique Block Dynamics & Perioperative Management Complications & How to Avoid Them
VI.	SUMMARY

INTRODUCTION

Cervical plexus anesthesia was developed early in the twentieth century, and two main approaches were available to the early practitioners of regional anesthesia. In 1912, Kappis described a posterior approach to the brachial plexus while attempting to block spinal nerves at the point of emergence from the vertebral column.¹ The main reason for a posterior approach to blocking the cervical plexus is the relative position of the vertebral artery and vein anterior to the plexus.² However, the posterior approach is associated with discomfort during and after the blockade, most likely due to the puncture of the extensor muscles of the neck, and has been avoided by many practitioners. As a result, the posterior approach to the cervical plexus block has not been as popular as the lateral approach, although it has been utilized to block the brachial plexus either as a single-shot or continuous technique.^2–5

In 1914 Heidenhein described the lateral approach, which has formed the basis for subsequent techniques of anesthetizing the cervical plexus.⁶ Victor Pauchet described a lateral approach to blocking the cervical plexus in 1920 and mentioned the posterior approach; however, he advocated the use of the lateral approach.⁷ Winnie revisited the lateral approach to the cervical plexus block in 1975, and it is currently the more used approach for the cervical plexus block.⁸

Figure 23-1. Carotid endarterectomy. The image shows open, cross-clamped carotid artery and a plaque inside its wall.

INDICATIONS & CONTRAINDICATIONS

Deep and superficial cervical plexus block can be used to provide anesthesia for a variety of surgical procedures, including superficial operations on the neck and shoulders, thyroid operations, and carotid endarterectomies in which awake neurologic monitoring is a simple and reliable method of neurologic assessment (Figure 23-1 ).^9,10 Eastcott described the first carotid endarterectomy in 1954, and the number of these surgeries performed in the United States grows each year.¹¹ Regional anesthesia is a viable anesthetic choice for carotid surgery, although debate continues about whether regional or general anesthesia is the better choice for carotid endarterectomy surgery. Most of the latest literature points to regional anesthesia as a better choice.^12–21 The outcome data from vascular surgery and neurosurgery literature shows that patients who undergo carotid endarterectomy under regional anesthesia may have better outcomes.^22–25

The superficial cervical plexus block can be used for many superficial surgeries in the neck area, including lymph node dissection, excision of thyroglossal or branchial cleft cysts, carotid endarterectomy, and vascular access surgery.²⁶ If the superficial cervical plexus block is to be used alone for carotid endarterectomy, local anesthetic supplementation by the surgeon may be necessary.^27,28 Although both the deep and superficial cervical plexus blocks can be performed separately, they are most often performed in combination to provide anesthesia and postoperative analgesia for head and neck surgery.^29–31

The main absolute contraindication to performing a cervical plexus block is patient refusal of regional anesthesia. Relative contraindications include infection at the site of injection, sepsis, preexisting central or peripheral nervous systems disorders, allergy to local anesthesia, and a long duration of surgery.

FUNCTIONAL ANATOMY OF DEEP CERVICAL PLEXUS BLOCKADE

The cervical plexus is formed by the anterior divisions of the four upper cervical nerves (Figure 23-2). The plexus is situated on the anterior surface of the four upper cervical vertebrae, resting on the levator anguli scapulae and scalenus medius muscles, and is covered by the sternocleidomastoid muscle. Their dorsal and ventral roots combine to form spinal nerves as they exit through the intervertebral foramen. The anterior rami of the second through fourth cervical nerves form the cervical plexus (the first cervical root is a primarily motor nerve and it is not blocked by this technique). The cervical plexus lies in the plane just behind the sternocleidomastoid muscle, giving off both superficial (superficial cervical plexus) and deep branches (deep cervical plexus). The branches of the superficial cervical plexus supply innervation to the skin and superficial structures of the head, neck, and shoulder (Figure 23-3). The deep branches of the cervical plexus innervate the deeper structures of the neck, including the muscles of the anterior neck and the diaphragm, which is innervated by the phrenic nerve. The third and fourth cervical nerves typically send a branch to the spinal accessory nerve, or directly into the deep surface of the trapezius to supply sensory fibers to this muscle. The fourth cervical nerve may send a branch downward to join the fifth cervical nerve and participate in the formation of the brachial plexus. The cutaneous innervation of both the deep and superficial cervical plexus blocks includes skin of the anterolateral neck and the ante- and retroauricular areas (Figure 23-4).

Anatomic Landmarks

The following three landmarks for a deep cervical plexus block are identified and marked (Figure 23-5):

1. Mastoid process

2. Chassaignac’s tubercle (transverse process of the sixth cervical vertebra)

3. Posterior border of the sternocleidomastoid muscle

To estimate the line of needle insertion that overlies the transverse processes, the mastoid process (MP) and Chassaignac’s tubercle, which is the transverse process of the sixth cervical vertebra (C6), are identified and marked (Figure 23-6). The transverse process of C6 is usually easily palpated behind the clavicular head of the sternocleidomastoid muscle at the level just below the cricoid cartilage (Figure 23-7). Next, a line is drawn connecting the MP to Chassaignac’s tubercle. Position the palpating hand just behind the posterior border of the sternocleidomastoid muscle. Once this line is drawn, label the insertion sites over the C2, C3, and C4, which are respectively located on the MP-C6 line 2 cm, 4 cm, and 6 cm caudal to the mastoid process. It is also possible to perform a single injection at the C3 level, which is considered safe and effective.³²

Figure 23-2. Anatomy of the cervical plexus.

Figure 23-3. Topographic anatomy of the cervical plexus.

Figure 23-4. Cutaneous coverage of the cervical plexus.

Figure 23-5. Anatomic landmarks for the cervical plexus block.

Figure 23-6. Anatomic landmarks for the cervical plexus. Shown are estimates of the transverse processes C2 through C6.

Figure 23-7. Palpation of the transverse process of C6.

Clinical Pearls

The distances specified for spacing along the transverse processes at various levels are only approximate estimates.

Once contact is made with the transverse processes at the first two levels, the spacing between the two neighboring transverse processes follows a similar pattern.

Choice of Local Anesthetic

A deep cervical plexus block requires 3-5 mL of local anesthetic per level to ensure reliable blockade. Except perhaps with patients with significant respiratory disease who rely on their phrenic nerve to adequately ventilate, most patients benefit from the use of a long-acting local anesthetic. Table 23-1 shows commonly used local anesthetics with onset and duration of anesthesia and analgesia for deep cervical plexus blocks. Ropivacaine is one option for deep cervical plexus block and 30-40 mL of the 0.5% concentration provides an excellent quality of block.³³ Ropivacaine has been shown to be a more suitable choice for carotid endarterectomy surgery.³⁴