Chapter 23. Cervical Plexus Block

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

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.

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. 1. Mastoid process

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

3. 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

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

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

• Sterile towels and 4- × 4-in. gauze pads
• 20-mL syringe(s) with local anesthetic
• Sterile gloves and marking pen
• One 1½-in., 25-gauge needle for skin infiltration
• A 1½-in.-long, 22-gauge, short-beveled needle

Technique

After cleaning the skin with an antiseptic solution, local anesthetic is infiltrated subcutaneously along the line over the transverse processes. The local anesthetic should be infiltrated over the entire length, rather than at the projected insertion sites to allow reinsertion of the needle slightly caudally or cranially when the transverse process is not contacted. This obviates the need to infiltrate the skin at a new insertion site.

The block needle is connected to a syringe with local anesthetic via flexible tubing. The needle is inserted between the palpating fingers and advanced at an angle perpendicular to the skin plane. The needle should never be oriented cephalad. A slight caudal orientation of the needle is the single best method for preventing the inadvertent insertion of the needle toward the cervical spinal cord. The needle is advanced slowly until the transverse process is contacted (Figure 23–8). At this point, the needle is withdrawn 1–2 mm and stabilized; then 4 mL of local anesthetic is injected after a negative aspiration test for blood. The block needle is then removed, and the entire procedure is repeated at the consecutive levels.

The goal for the deep cervical plexus block is to contact the posterior tubercle of the transverse process because the spinal nerves at the individual levels are located just in front of the transverse process.

Although the placement of deep cervical block may be associated with moderate patient discomfort, avoid excessive sedation. During neck surgery, airway management may be difficult due to the need to share access to the head and neck with the surgeon. Surgeries like carotid endarterectomy require that the patient be fully conscious, oriented, and cooperative during the entire surgical procedure.13 In addition, excessive sedation and the consequent lack of patient cooperation can result in restlessness and create difficulty for the surgeon. The onset time for this block is 10–15 min. The first sign of deep cervical plexus blockade is decreased sensation in the area of the distribution of the respective components of the cervical plexus. It should be noted that due to the complex arrangement of the neuronal coverage of the various layers in the neck area as well as the cross coverage from the contralateral side, the anesthesia achieved with cervical plexus block is rarely complete. Although this should not discourage the practitioner from using the deep cervical plexus block, its use does require an understanding surgeon who is willing to supplement the block with the local anesthetic as necessary.

The superficial cervical plexus supplies innervation to the skin of the anterolateral neck through anterior primary rami of the second through fourth cervical nerves (see Figure 23–4). The individual nerves emerge as four distinct nerves from the posterior border of the sternocleidomastoid muscle. The lesser occipital nerve usually is a direct branch from the main stem of the second cervical nerve. The larger remaining part of this stem then unites with a part of the third cervical nerve to form a trunk that arises as the greater auricular and the transverse cervical nerves. Another part of the third cervical nerve runs downward to unite with a major part of the fourth to form a supraclavicular trunk, which then divides into the three groups of supraclavicular nerves.

Anatomic Landmarks

A line extending from the mastoid to C6 is drawn (Figure 23–9). The site of needle insertion is marked at the midpoint of the line connecting the mastoid process with Chassaignac's tubercle of C6 transverse process (see Figure 23–9). This is the location of the branches of the superficial cervical plexus as they emerge behind the posterior border of the sternocleidomastoid muscle.

Choice of Local Anesthetic

A superficial cervical plexus block requires 10–15 mL of local anesthetic (3–5 mL per each redirection/injection). Most patients benefit from the use of a long-acting local anesthetic. Since motor block is not sought with this technique, some anesthesiologists suggest using a low concentration of local anesthetic (eg, 0.2–0.5% ropivacaine or 0.25% bupivacaine). Although a low concentration may suffice when the needle is ideally placed in the vicinity of the cervical plexus nerves, this is often not the case, and the higher concentration will result in both a higher success rate and a longer duration of blockade.33Table 23–1 shows choices of local anesthetic, with their onset time and duration of anesthesia and analgesia.

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

• Sterile towels and 4- × 4-in. gauze pads
• 20-mL syringe with local anesthetic
• Sterile gloves, marking pen, and surface electrode
• A 1½-in., 25-gauge needle for block infiltration

Technique

After skin cleaning with an antiseptic solution, a skin wheal is raised at the site of needle insertion using a 25-gauge needle. Next, using a “fan” technique with superior–inferior needle redirections, the local anesthetic is injected alongside the posterior border of the sternocleidomastoid muscle 2–3 cm below and then above the needle insertion site. This injection technique should be adequate to achieve blockade of all four major branches of the superficial cervical plexus (Figure 23–10).

The goal of the injection is to infiltrate the local anesthetic subcutaneously and behind the sternocleidomastoid muscle. Deep needle insertion should be avoided (eg, >1–2 cm).

Block Dynamics & Perioperative Management

The superficial cervical plexus block is associated with minor patient discomfort. Small doses (1–2 mg) of midazolam for sedation and alfentanil (250–500 mcg) for analgesia just before needle insertion should produce a comfortable and cooperative patient during nerve localization. Similar to deep cervical plexus blockade, the sensory coverage of the neck is complex and a degree of cross-coverage from the cervical plexus branches from the opposite side of the neck should be expected. The onset time for this block is 10–15 min; the first sign of the blockade is decreased sensation in the area of the distribution of the respective components of the cervical plexus.

Complications & How to Avoid Them

Complications can occur with both deep and superficial cervical plexus block (Table 23–2). Infection, hematoma formation, phrenic nerve block, local anesthetic toxicity, nerve injury, and inadvertent subarachnoid or epidural anesthesia can all occur when performing these blocks.35–39 In a large prospective study of 1000 blocks for carotid artery surgery, Davies and colleagues reported only 6 blocks (0.6%) showing evidence of intravascular injection.13 Other possible complications include transient ischemic attacks either during surgery or in the postoperative period and recurrent laryngeal nerve blockade.40–42 As with other nerve blockade procedures, if attention is paid to details, the risk of complications can be minimized when performing cervical plexus blocks and result in a safe and efficacious method of performing anesthesia that has high patient acceptance.43–46

In summary, cervical plexus block has been in clinical use for nearly a century. Although modifications have been made to the approaches first described at the beginning of the twentieth century, the most common approach remains the lateral approach to deep cervical plexus block.