Ultrasound-guided cervical intra-articular facet block is utilized most frequently as a diagnostic maneuver to confirm that a specific facet joint is in fact the source of the patient’s neck or headache pain. Ultrasound-guided blockade of the cervical medial branch is also useful in the diagnosis and treatment of cervicogenic headache, cervicalgia, arthritis of the cervical facet joints, and other pain syndromes that are due to facet joint dysfunction or disease. These disease processes present clinically as cervicalgia, suboccipital headache, and, occasionally, shoulder and supraclavicular pain.

Except for the atlanto-occipital and atlantoaxial joints, the cervical facet joints (which are also known as the zygapophyseal joints) are formed by the articulations of the superior and inferior articular facets of adjacent vertebra (Fig. 28.1). The cervical facet joints are true joints, which are lined with synovium, contain cartilage and menisci, and are enclosed in a true joint capsule. This joint capsule is richly innervated and supports the notion of the facet joint as a pain generator. The cervical facet joint is susceptible to arthritic changes and trauma caused by acceleration-deceleration injuries. Such damage to the joint results in pain secondary to synovial joint inflammation and adhesions.

Each facet joint receives innervation from two spinal levels, receiving fibers from the dorsal ramus at the same level as the vertebra as well as fibers from the dorsal ramus of the vertebra above (Fig. 28.2). This fact is important clinically for two reasons: (1) it provides an explanation for the ill-defined nature of facet-mediated pain and (2) it also explains why the medial branch from the vertebra above the painful joint as well as the medial branch at the level of the painful joint must both be blocked to provide complete pain relief. At each level, the dorsal ramus provides a medial branch that wraps around the convexity of the articular pillar of its respective vertebra (Fig. 28.3). This location is constant for the C3-C4 through the C8-T1 facet joint nerves and allows a simplified approach to ultrasound-guided intra-articular facet block. The atlanto-occipital and atlantoaxial joints are not innervated by medial branches but by branches of the respective C1 and C2 ventral rami (see Chapters 1 and 2). The C2-C3 facet joint is innervated primarily by the third occipital nerve, which arises from medial branch fibers of the posterior division of the third cervical nerve (see Chapter 26).

Ultrasound-guided cervical intra-articular facet block can be carried out by placing the patient in the prone position. A total of 0.25 to 0.5 mL of local anesthetic is drawn up in a 10-mL sterile syringe for each medial branch to be blocked. If the painful condition being treated is thought to have an inflammatory component, 40 to 80 mg of depot steroid is added to the local anesthetic.

The midline of the cervical spine is identified by palpation of the spinous processes (Fig. 28.4). After preparation of the skin with antiseptic solution, a linear high-frequency ultrasound transducer is placed in a longitudinal plane at the level of the occiput, and the spinous processes starting at C1 are identified (Fig. 28.5). C1 has only a vestigial spinous process as compared with the remaining cervical vertebra, and the more pronounced bifid spinous process of C2 can aid the clinician when counting the cervical vertebra to identify the facet joint to be blocked (Figs. 28.6 and 28.7). After the proper level has been identified, the ultrasound transducer is slowly moved laterally until the articular pillars of the facet joints appear with their characteristic wavy or sawtooth appearance (Fig. 28.8). The transducer is then rocked slightly laterally or medially until the facet joint, which appears as an anechoic gap between the two hyperechoic echoes of the superior and inferior articular processes, is clearly visualized (Fig. 28.9). A 3½-inch styletted spinal needle is then inserted beneath the caudal end of the ultrasound transducer utilizing an in-plane approach and is advanced from a caudad to cephalad trajectory into the facet joint (Figs. 28.10 and 28.11). After gentle aspiration, 0.25 to 0.5 mL of solution is injected with care being taken to avoid the vertebral artery, which is located anteriorly in relation to the facet joints. The needle is removed and pressure is placed on the injection site to avoid hematoma formation.