Introduction
Cervical facet joints, also known as zygapophyseal joints, are a common cause of neck, head, and/or shoulder pain due to degenerative changes, accounting for up to 25–55% of chronic neck pain. , Patient history and physical examination are important components of a cervical facetogenic pain assessment but can be unreliable without diagnostic imaging or cervical medial branch blocks (CMBB). Imaging studies can be helpful to exclude other etiologies of neck pain but are also non-diagnostic. While knowledge of cervical facet joint pain referral patterns is helpful in selecting which specific facet joints may be contributing to a patient’s pain, dual local anesthetic CMBBs are recommended to validate the diagnosis of facet-mediated pain. Ultimately, CMBBs serve primarily as diagnostic procedures for facetogenic pain.
The current standard for interventional treatment of cervical facetogenic pain is cervical medial branch radiofrequency ablation (CMB RFA). CMB RFA is typically done after dual CMBBs have been performed to confirm that modulation of the medial branches can improve patient symptoms. CMB RFA can provide pain relief for as long as 6 to 12 months. This chapter describes the most commonly performed techniques for CMBB and CMB RFA.
Anatomy
Cervical facet joints are paired diarthrodial joints that connect adjacent superior and inferior vertebrae, spanning from C2–C3 to C7–T1. They are composed of the inferior articular process (IAP) of the upper vertebrae and the superior articular process (SAP) of the lower vertebrae. These joints are localized to the posterior aspect of the cervical column (see Figs. 5.1 and 5.2 ).
Sensory innervation of the facet joints from C3–C4 to C7–T1 is supplied by the medial branches of the dorsal primary rami of the spinal nerves at the same level and the descending branch of the level above, crossing the lateral concavity (or “waist”) of the articular pillar of the vertebrae (see Figs. 5.2 and 5.3 ). For example, the C4–C5 facet joint is innervated by the C4 and C5 medial branches. Thus, two medial branches must be anesthetized per facet joint. An important exception is the C2–C3 facet joint, which is primarily innervated by the third occipital nerve (TON). The TON is the superficial medial branch of the C3 dorsal ramus and is located along the lateral surface of the C2–C3 facet joint. The TON is distinct from the deep medial branch of the C3 dorsal ramus, which in combination with the C4 medial branch, innervates the C3–C4 facet joint.
Diagnosis
Cervical facetogenic pain typically presents as localized axial neck pain without significant radiation into the upper extremities. Depending on the level involved, referred patterns of pain may also occur, which facilitate segment selection. These referred patterns include the posterior scapular region for the lower facets, shoulder for the middle facets, or occipital headaches for the upper facets. Onset is typically insidious in nature, becoming gradually worse over months or years. Acute instances of cervical facetogenic pain can occur following a whiplash injury, with the C5–C6 facet joint thought to be the most commonly involved. The C2–C3 facet joint is most commonly implicated when patients present with cervicogenic headaches.
A physical exam of cervical facetogenic pain typically demonstrates pain with neck extension, rotation or side bending, and tenderness to deep palpation along the facet joint line. Diagnostic imaging studies may be normal or show facet arthropathy. Albeit useful and clinically important, physical examinations and imaging have significant limitations, and dual diagnostic CMBBs are imperative for diagnosing facet joint-mediated pain. Two blocks are preferred as single diagnostic medial branch blocks have a high false positive rate.
Following the CMBB procedure, pain relief and function are typically assessed. Commonly used tools for evaluation include diaries recording pain scores in the form of a visual analog scale or numerical pain rating scale. Furthermore, changes in activities of daily living affected by the pain are recorded. Depending on the type, volume, and concentration of local anesthetic used, effect onset and duration of CMBB may vary. Commonly used local anesthetics include lidocaine and bupivacaine, the latter having a slower onset of action but longer lasting effect. Comparative blocks with two different local anesthetics can be useful in validating the diagnosis of true facetogenic pain.
Cervical medial branch block procedure
CMBB may be performed with the patient in the prone or lateral decubitus positions. There are advantages and disadvantages to both of these approaches (see Table 5.1 ). Lateral decubitus positioning will be discussed in the context of CMBB, while prone positioning will be discussed in the context of CMB RFA.
| Prone | Lateral Decubitus | |
| Laterality | Ideal for bilateral procedures | Requires repositioning for bilateral procedures |
| Lower facet articular pillar visualization | Simple to visualize | Potentially difficult or impossible to visualize. Can be potentially avoided using a modified swimmer’s view |
| Skin-to-target distance | Longer, potentially more painful | Shorter, potentially less painful |
| MBB vs. RFA | Ideal for both | Ideal for MBB only, as electrodes cannot be placed parallel to the nerves |
| Safety concerns | Theoretical risk of injury to spinal nerve or vertebral artery if needle strays ventrally | Theoretical risk of injury to lung apex when targeting lower cervical facets |
Cervical medial branch block—lateral decubitus approach
- 1.
The patient is placed in the lateral decubitus position with a pillow under the head such that the neck is in a neutral position in all planes, paying particular attention to minimizing lateral cervical flexion (see Fig. 5.4 ).
- a.
A spot AP film should be obtained. The selected articular pillar should be perpendicular to the fluoroscopy beam to obtain a true view. If the articular pillars of interest are obscured by the shoulders and are not clearly visualized (see Fig. 5.5 ), the patient can be repositioned in a “modified swimmer’s” position where the shoulder closest to the table is flexed forward and above the head to about 135 degrees (see Fig. 5.6 ).
Fig. 5.5
AP view showing lateral cervical spine. Note how the articular pillars of C4 and below are obscured by the shoulders.
Fig. 5.6
Modified swimmer’s position. The shoulder closest to the table is flexed forward and above the head to about 135 degrees.
- b.
If the articular pillars of interest are still not clearly visualized, the patient should be repositioned and the procedure should be performed in the prone position as outlined in the next section.
Fig. 5.4
Patient positioned in a lateral decubitus position. A cervical pillow is used to maintain the cervical spine in the neutral position, avoiding excessive lateral flexion.
- a.
- 2.
The skin is cleaned and draped in typical sterile fashion.
- 3.
An AP view showing the lateral cervical spine is obtained. The vertebrae are then counted, using C2 as a reference (see Fig. 5.7 ).
- a.
The ipsilateral and contralateral facet joint lines caudad and rostral to the targeted articular pillar should be fairly superimposed over one another. This is achieved by using a combination of tilt and obliquity.
Fig. 5.7
AP view of the cervical spine in a lateral decubitus position. Legend: black lines, approximate location of cervical medial branches at each specified level; blue line, approximate location of the third occipital nerve (TON).
- a.
- 4.
The midpoint of the articular pillar of interest is located using a radiopaque marker, such as a bent 18-gauge needle (see Fig. 5.8 ), and a small-gauge needle (typically 25-gauge) with a bent tip for steering is inserted at the location (see Fig. 5.9 ). We recommend using the shortest needle length possible for ease of maneuverability.
Fig. 5.8
AP view of a patient with anterior hardware from C3 to C6. A bent 18-gauge needle is placed on the skin, with the needle tip lying at about the midpoint of the C3 articular pillar, the target of a C3 medial branch block. Note that the C3-C4 facet joint line is sharp, meaning that the ipsilateral and contralateral joints are superimposed. The C2-C3 facet joint line is not as sharp, and a more oblique or tilted position could have been utilized to obtain a true lateral.Related posts:
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