Fig. 16.1
Deep cervical plexus anatomy
16.2.1 Patient Positioning
Supine with a small towel or pillow under the head, which is turned 45° to the contralateral side with slight neck extension
16.2.2 Landmarks and Surface Anatomy (Fig. 16.2)
Fig. 16.2
Patient positioning and surface landmarks for a deep cervical plexus block. SCM sternocleidomastoid muscle
Landmarks include the posterior edge of the sternocleidomastoid muscle, the caudal portion of the mastoid process (see Clinical Pearls), the angle of the jaw, and the transverse processes of cervical vertebrae C2–C5.
If no transverse processes can be palpated, the transverse process of C6 can be located at the level of the cricoid cartilage. A line is drawn from the mastoid process along the sternocleidomastoid muscle to the transverse process of C6. Each transverse process of C2–C5 is marked approximately 0.5–1 cm behind the line. The transverse process of C2 lies about 1–1.5 cm inferior to the mastoid process, depending on the age and size of the patient. Deep cervical plexus block is a variation of cervical paravertebral nerve block of C2–C4.
16.2.3 Needle Insertion Technique
Three injections using a 22G–24G needle at the level of C2–C4 perpendicular to the horizontal plane and advanced slightly caudally and posteriorly (it is very important to avoid inadvertent intrathecal or epidural injection into the vertebral artery). The needle will typically contact the posterior tubercle of the transverse process (Fig. 16.1), upon which, the needle is withdrawn slightly, and the local anesthetic is injected after negative aspiration.
16.2.4 Nerve Localization and Local Anesthetic Application
A nerve stimulator attached to an insulated needle can be used to localize the mixed spinal nerves. Correct position of the needle tip is confirmed when current intensity of 0.5 mA elicits a local neck muscle response [1].
Concurrent use of ultrasound guidance is recommended to improve safety and efficacy of this block. The ultrasound image with corresponding MRI and VHVS images is shown in Figs. 16.3 and 16.4, where a selective deep cervical plexus block is performed in the groove between the longus capitis and scalenus medius.
Fig. 16.3
VHVS and MRI images of the deep cervical plexus
Fig. 16.4
Ultrasound image of the deep cervical plexus
After confirming contact with the transverse process, the needle is withdrawn slightly and a syringe is connected.
The dose of local anesthetic should be considered carefully, especially when multiple injections are performed. A dilute solution (0.5–1.0 % lidocaine [maximum dose 7 mg/kg] or 0.125–0.25 % bupivacaine [maximum dose 2 mg/kg]) with epinephrine (1:200,000 or 1:400,000) to detect inadvertent intravenous injection should be used. Generally, 1–3 mL of the solution is used at each injection site.
Clinical Pearls
At birth, the mastoid process only represents a small portion of the temporal bone. The mastoid width and depth increases rapidly up to the age of 7 years with no apparent gender dimorphism. The maximum size is apparent between years 11 and 19. This should be considered when palpating the attachment of the sternocleidomastoid muscle as a landmark for these blocks.
The deep block may be performed by single injection at C3 or C4 as originally described by Winnie or by a standard three-injection technique.
There are several life-threatening complications that may arise from deep cervical plexus block. A caudally directed needle is imperative; otherwise, injection into the vertebral artery (Fig. 16.5) may occur, potentially leading to convulsions, unconsciousness, and blindness. Subarachnoid or epidural injections are possible if the needle is advanced too far medially into the vertebral foramen. This is more likely in the cervical region because of the longer dural sleeves that accompany these nerve branches. Careful monitoring of the patient should continue for 60 min after the block has been performed.
Fig. 16.5
Ultrasound image highlighting the close proximity of the vertebral artery to the deep cervical plexus
Phrenic nerve palsy leading to hemidiaphragmatic paresis is a common occurrence with this block; therefore, care must be taken in young children. Bilateral blocks are not recommended. Minimizing the volume of local anesthetic may limit blockade of the phrenic nerve.
Other well-described side effects include Horner’s syndrome (if the superior cervical or cervicothoracic ganglion is blocked), stellate ganglion block, and hoarseness due to recurrent laryngeal nerve block.
The authors did not recommend performing the deep cervical plexus block unless it is strongly indicated.
16.2.5 Current Literature for Deep Cervical Plexus Block
Zeidan described a nerve stimulator-guided deep cervical plexus block for carotid endarterectomy [1]. The transverse process is identified 1 cm posterior to the posterior border of the sternocleidomastoid. With a block needle connected to a nerve stimulator, the needle is inserted perpendicular to the skin, aiming slightly caudal at C2 level to elicit neck muscle contraction at a current intensity of 0.5 mA. Excellent results were reported with this technique; however, there was no description of the specific type of muscle response elicited to confirm correct placement of the needle versus direct muscle contraction from the stimulating needle itself. Data on pediatric patients are lacking.
A recent case series by Perisanidis et al. [2] assessed combined deep and intermediate cervical plexus block for oral and maxillofacial surgery in adults. Under ultrasound guidance, the authors injected 15 mL ropivacaine 0.75 % between the sternocleidomastoid and levator of the scapula muscles; after which, the needle was advanced to a position between the levator of the scapula and cervical transverse process, where another injection of 15 mL ropivacaine 0.75 % was done. All blocks were successful with no need for supplementary analgesics in the 24 h post-block period. Obviously, this dosage is too high for the pediatric population.
There have been reports of successful cervical plexus blocks to provide surgical anesthesia for lymph node biopsy and excision of thyroid nodules in adolescents using a single injection at the level of C3 [3]. When reviewing the literature describing ultrasound imaging techniques of deep cervical block in adults, the two most useful sonographic landmarks appear to be the groove between the longus capitis and scalenus medius [4] and the sulcus between the anterior and posterior tubercles of the transverse processes and posterior to the vertebral artery [5, 6].
16.3 Ultrasound-Guided Superficial Cervical Plexus Block
This block aims to anesthetize the four branches of the superficial cervical plexus, namely, the lesser occipital nerve, the great auricular nerve, the anterior or transverse cervical nerve, and the supraclavicular nerve (Fig. 16.6). These are all branches from the anterior primary rami of the C1–C4 nerve roots. Superficial cervical plexus block provides anesthesia to the ipsilateral occipital region, some of the ear, the anterior and posterior triangles of the neck, and the upper back, shoulder, and upper pectoral regions.
