Cervical plexus block

Abstract

Cervical plexus blocks (CPBs) have been used in various head and neck surgeries to provide adequate anesthesia and/or analgesia; however, the block is performed in a narrow space in the region of the neck that contains many sensitive structures, multiple fascial layers, and complicated innervation. Since the intermediate CPB was introduced in addition to superficial and deep CPBs in 2004, there has been some confusion regarding the nomenclature and definition of CPBs, particularly the intermediate CPB. Additionally, as the role of ultrasound in the head and neck region has expanded, CPBs can be performed more safely and accurately under ultrasound guidance. In this review, the authors will describe the methods, including ultrasound-guided techniques, and clinical applications of conventional deep and superficial CPBs; in addition, the authors will discuss the controversial issues regarding intermediate CPBs, including nomenclature and associated potential adverse effects that may often be neglected, focusing on the anatomy of the cervical fascial layers and cervical plexus. Finally, the authors will attempt to refine the classification of CPB methods based on the target compartments, which can be easily identified under ultrasound guidance, with consideration of the effects of each method of CPB.

Keywords: Cervical fascia; Cervical plexus; Cervical plexus block; Phrenic nerve palsy; Ultrasonography; Airway obstruction.

Fig. 1.

The layers of cervical fascia (C6 transverse section) as suggested by Guidera et al. [35]. The illustration is adapted from Smoker and Harnsberger [41].

Fig. 2.

Schematic drawing of the deep cervical plexus and superficial cervical plexus. (A) Four superficial branches of the cervical plexus are depicted using yellow color, and deep branches of cervical plexus (ansa cervicalis) are depicted using green color. The cervical plexus is known to anastomose with several cranial nerves and the sympathetic trunk. (B) The superficial cervical plexus emerges behind the posterior border of the SCM (sternocleidomastoid) muscle and innervates the head, neck, and shoulder areas. The illustration is adapted from Restrepo et al. [52].

Fig. 3.

Landmark-based superficial cer vical plexus blocks have been performed for ear, neck, and upper chest wall surgeries to obtain adequate anesthesia and/or analgesia in Ajou University Hospital. (A) Great auricular and lesser occipital nerve blocks were performed in a 77-year-old male patient undergoing excision of ear hemangioma. (B) Selective supraclavicular nerve block was performed in a 4-year-old female patient undergoing excision of a congenital melanocytic nevus on the right upper chest wall. (C) Great auricular and transverse cervical nerve blocks were performed in a 94-year-old female patient undergoing excision of a squamous cell carcinoma on the right neck area. (D) Selective supraclavicular nerve block was performed in a 52-year-old male patient undergoing incision and drainage of an abscess on the right upper chest wall. To avoid deep injection, the needle was bent slightly.

Fig. 4.

Ultrasound image of the posterior approach for an intermediate cervical plexus block at C4-5 level in a 3-year-old torticollis patient undergoing unipolar sternocleidomastoid (SCM) release with myectomy. Hydrodissection of the posterior cervical space between the SCM muscle and prevertebral fascia by local anesthetic is seen, and local anesthetic spreads to the area near the carotid sheath. CA: carotid artery, IJV: internal jugular vein, LA: local anesthetic. White arrow points: prevertebral fascia.

Fig. 5.

Three different target areas of cervical plexus blocks (CPBs) in the cervical fascial spaces are depicted schematically (C4 transverse section). (A) The target area for superficial CPB is subcutaneous tissue around the mid portion of posterior border of the sternocleidomastoid (SCM) muscle. (B) The target area for intermediate CPB is the space between the SCM muscle and the prevertebral fascia. (C) The target area for deep CPB is the space between the prevertebral fascia and the target transverse process.