Superficial cervical plexus nerve block (ultrasound)

The superficial cervical plexus nerve block is a field block indicated for procedures involving, and anesthesia of, the anterolateral neck and the skin overlying the clavicle. The superficial cervical plexus (SCP) includes the greater auricular, lesser occipital, transverse cervical, and supraclavicular nerves ⁵.

Indications

• clavicular fracture
• internal jugular central line placement
• carotid endarterectomy ³
• auricular laceration repair
• submandibular abscess

Contraindications

• local infection
• local anesthetic allergy
• patient refusal

Procedure

Positioning/room set up

IV access should be obtained, and the patient should be placed on a cardiac monitor. The ultrasound machine should be optimally positioned for ergonomic visualization during the procedure, typically on the opposite side of the bed. The patient is positioned supine or semi-supine with their head rotated to the contralateral side. 

Equipment

• standard nerve block tray
• 1.5 inch 25 gauge block needle
• low volume extension tubing
• sterile gloves
• linear ultrasound transducer
• sterile ultrasound transducer sleeve
• 6-10mL of local anesthetic
  • bupivacaine 0.25% is a common choice

Technique

The relevant anatomy is first defined with a high frequency linear probe, placed in a transverse orientation at the midpoint between the mastoid process and clavicle, just over and slightly posterior to the sternocleidomastoid muscle. The superior aspect of the thyroid cartilage is another common anatomic landmark. Disinfection of the skin and appropriate draping should precede initiation of the procedure ².

Once the sternocleidomastoid is visualized, the transducer is slid posteriorly until the lateral edge of the muscle is visualized, overlying the levator scapulae muscle and (more caudad) interscalene groove. Care should be taken to visualize the local neurovascular anatomy, including the internal jugular vein, external jugular vein, common carotid artery and the brachial plexus. 

The fascial plane between the levator scapulae and sternocleidomastoid may then be identified. Within its striated, hyperechoic substance the circular, hypoechoic cluster may be visualized which represents the superficial cervical plexus, typically just deep to the posterior surface of the lateral sternocleidomastoid.

Using an in-plane technique, the needle is inserted as parallel as possible to the ultrasound beam, from posterolateral to medial.  The needle is advanced through the skin and platysma under real-time guidance until just short of the plexus. Following aspiration to ensure the needle tip is not within a vascular structure, hydrodissection is used to confirm the optimal anesthetic placement, and 10 mL of local anesthetic administered in ~2 mL aliquots should proceed until linear spread across the deep margin of the SCM is acheived.

Complications

• paralysis of structures innervated by the
  • accessory nerve
  • recurrent laryngeal nerve
  • vagus nerve
  • phrenic nerve
• horner syndrome ⁶