A

Figure 11.7. Oblique radiograph along the plane of a lumbar facet joint. The articular surfaces of the superior and inferior articular processes are seen en face. Although this projection is the best depiction of the articular surfaces, the posterior opening in the joint may not lie directly in this plane because the articular surfaces are sometimes curved. Injecting at the superior or inferior articular recess may help maximize access to the joint for intra-articular injections.

is encountered. The needle may be advanced into the middle aspect of the joint, although I prefer to advance into the inferior or superior aspect of the joint because there is some redundancy in the superior and inferior recesses that makes intra-articular placement less difficult. If intra-articular placement is desired, a small amount (0.3-0.5 mL) of contrast material is injected slowly under fluoroscopy (Figure 11.8). If the needle tip is intra-articular, contrast material will extend into the joint and fill the superior and inferior articular recesses. If contrast material pools at the needle tip or extends into the multifidus muscle, the stylet is replaced within the needle, and the needle is partially withdrawn and redirected into the joint. The needle can typically be felt to enter the joint as it is walked off the bone locally. When placement has been confirmed by arthrogram, the block is carried out by intra-artic-ular injection of solution containing a local anesthetic (e.g., 1-1.5 mL of 0.25% bupivacaine), with or without a long-acting corticosteroid (e.g., 10-40 mg of methylprednisolone in solution). The patient should be monitored for a pain response, since typical or concordant pain symptoms may sometimes be elicited on capsular distension. Injection of larger volumes of anesthetic should be avoided in diagnostic blockage, specifically to avoid capsular rupture and leakage of anesthetic into the soft tissues, which might anesthetize other levels and cloud diagnostic accuracy.

Inferior Capsular Tear

Figure 11.7. Oblique radiograph along the plane of a lumbar facet joint. The articular surfaces of the superior and inferior articular processes are seen en face. Although this projection is the best depiction of the articular surfaces, the posterior opening in the joint may not lie directly in this plane because the articular surfaces are sometimes curved. Injecting at the superior or inferior articular recess may help maximize access to the joint for intra-articular injections.

Figure 11.8. Oblique radiograph of the lumbar spine demonstrating a typical lumbar facet joint arthrogram. A small volume of contrast material can be seen between the superior and inferior articular processes, and extending into the capsular recesses.

Figure 11.8. Oblique radiograph of the lumbar spine demonstrating a typical lumbar facet joint arthrogram. A small volume of contrast material can be seen between the superior and inferior articular processes, and extending into the capsular recesses.

Lumbar Facet Arthrogram

For periarticular injection, the approach is identical to that used for intra-articular injection, but arthrography is not performed. The needle is advanced to contact bone at the level of the joint capsule. After negative aspiration to confirm needle tip positioning outside the vas-culature, the injection is performed. A slightly larger volume may be injected (up to 2-2.5 mL of anesthetic with steroid), and the needle may be partially withdrawn and redirected to other sites along the same joint capsule to "pepper" the joint with anesthetic. Negative aspiration for blood should be performed prior to injection to confirm positioning outside the vascular space. For multiple injections at the same setting, corticosteroid quantities for each joint may be reduced to keep the total dose within reasonable limits (80-120 mg of methylpred-nisolone).

In the cervical spine, the approach is typically from posterior or pos-terolateral, although a lateral approach has been described as well. An IV line is typically started in all patients for cervical injections in the event that IV medication or fluid bolus may be necessary; IV conscious sedation may be used but is frequently not necessary. The cervical facet joints are angled in a coronal plane from superior to inferior. Joint access is facilitated by approaching the joint from posterior and below. The patient should be positioned prone with chest elevated on a bol ster and the neck slightly flexed. Positioning with arms at the patient's sides will facilitate lateral fluoroscopy when this is needed; positioning with arms over the head prohibits lateral viewing. The fluoroscopy tube is angled in a caudocranial direction to visualize the lateral masses and articular facets (Figure 11.9). The cervical facet joints are difficult to visualize directly along the plane of the joint, and the joint space is frequently not seen directly, though its position is inferred between adjacent lateral masses. The joint can be visualized laterally. A 22- or 25-gauge spinal needle is used to enter the skin roughly 2 cm below the joint and is angled superiorly to enter the posterior and inferior aspect of the joint (Figure 11.10). Local anesthesia may be used, although it is not necessary, particularly if the smaller needle gauge is used. A posterior or posterior oblique approach avoids damage to critical vascular structures. Care should be taken to ensure that the needle tip remains over the lateral masses and away from the central canal to avoid inadvertent dural puncture. When bone is encountered, the tube can be turned to lateral projection to confirm positioning in the joint. Minor readjustments of position can be made under lateral fluoroscopy. Arthrography may be performed with intra-articular injection of 0.2 to 0.5 mL of iodinated contrast medium (Figure 11.11). After negative aspiration, 0.5 to 1.0 mL of local anesthetic may be injected with or with-

Figure 11.9. Caudocranially angled posterior-anterior (PA) radiograph of the cervical spine, demonstrating the angulation of the cervical facet joints. Access to the joints is facilitated by an approach from the inferior direction, although a direct approach along the plane of the joint is often difficult because it may entail traversing the musculature of the upper back. A posterior approach is made from the inferior direction to maximize accessibility of the joint, although a direct approach along the plane of the joint is frequently not possible.

Figure 11.10. Lateral radiograph of a cervical spine showing a needle in a cervical facet joint. An inferior approach has been taken to access the joint, although the coronal orientation of the joint makes access along the plane of the joint difficult.

Direct Body Orientation

out corticosteroid (e.g., 10-20 mg of methylprednisolone). As in the lumbar spine, a higher volume of injectate may be used if periarticu-lar injection is undertaken rather than intra-articular.

Thoracic facet joint blocks are infrequently requested, although those joints in some rare instances are a source of pain. The orientation of the joint is similar to that of the cervical facet joints, although more steeply angled craniocaudally. The procedure is performed from a posterior approach similar to that used in the cervical spine, although the needle may require steeper caudocranial angulation for intra-articular technique.

Medial Branch Block (Facet Joint Nerve Block) Technique

As an alternative to joint injection, the medial branch of the dorsal ra-mus can be blocked directly. Medial branch blocks are typically chosen in the setting of preprocedural screening prior to medial branch rhizotomy, since some studies have demonstrated a higher predictive value for rhizotomy results when medial branch blocks are performed,

Figure 11.11. (A) Lateral and (B) PA radiographs of the cervical facet joints following intra-articular injection of 0.3 mL of iodinated contrast. Initial injection of contrast pooled along the posterior aspect of the joint capsule, although after repositioning of the needle in the lateral plane, the second injection demonstrates contrast within the joint extending between the articular processes.

Facet Joint Injections Anatomy

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