Extraarticular Medial Branch Block

Dorn Spinal Therapy

Spine Healing Therapy

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Medial branch blocks at the levels of C3 to C6 are performed most readily in the lateral projection with the affected side up. The target is the center of the articular pillar for branches C3 to C6, with the needle tip abutting the bone at the intersection of the two diagonals of the diamond-shaped articular pillar (Fig. 6). A fluoroscopic true lateral projection of the articular pillars is essential to avoid inserting the needle deep to the pillars and possibly into the spinal canal. Fluoroscopy in the AP plane will confirm the position of the needle against the lateral cortex at the waist of the articular pillar. The injection of 0.3 mL of contrast will

FIGURE 2 Intra-articular block at C6-C7; lateral approach. A 25-gauge needle is advanced to the superolateral cortex of the C6-C7 facet joint, with the patient in the lateral decubitus position. The C arm is rotated 90°, and the needle-tip position is confirmed in the anteroposterior (AP) projection (A). The needle tip is adjusted to just enter the capsule, and 0.3 to 0.5 mL of nonionic contrast is injected under fluoroscopy in the lateral projection (B) and imaged in the AP projection (C).

FIGURE 2 Intra-articular block at C6-C7; lateral approach. A 25-gauge needle is advanced to the superolateral cortex of the C6-C7 facet joint, with the patient in the lateral decubitus position. The C arm is rotated 90°, and the needle-tip position is confirmed in the anteroposterior (AP) projection (A). The needle tip is adjusted to just enter the capsule, and 0.3 to 0.5 mL of nonionic contrast is injected under fluoroscopy in the lateral projection (B) and imaged in the AP projection (C).

FIGURE 3 Lateral projection. Intra-articular C2-C3 block. A 25-gauge needle placed on the C2 articular cortex to just enter the joint capsule. A small bore, short-extension tube is attached to the needle to allow the exchange of syringes without disturbing the needle position. This is followed by the injection of 0.3 cc of contrast, followed by 1.0 cc of local anesthesia with or without a corticosteroid.

FIGURE 4 Axial computed tomography scan. Intraarticular block, C1-C2; posterior approach. A 25-gauge needle has been localized to the posterior lateral-third of the joint to avoid the C2 spinal nerve dural sac or C2 root sleeve. The periphery of the joint is outlined by contrast.

FIGURE 5 Anteroposterior projection. Intra-articular block, C1-C2; lateral approach. Contrast arthrogram outlines the joint capsule. Notice the needle tip remains within the lateral aspect of the joint to avoid inadvertent passage into the spinal canal.

FIGURE 6 (A) Lateral and (B) anteroposterior projection. Extra-articular C5 medial branch block, lateral approach. The needle is aimed to reach the midpoint or waist of the facet pillar. The injection of 0.5 mL of contrast excludes intravenous washout and is followed with injection of 0.3 to 0.5 mL of local anesthetic.

exclude an intravenous position and washout. This is followed by the administration of 0.3 mL of local anesthesia to the target nerve.

The medial branch block of C7 requires placement of the needle superior to the base of the transverse process within the middle of the upper portion of the pillar. Once the needle contacts the bone, an AP view is obtained to be certain that the needle tip is not lodged on the transverse process but superior to base of the transverse process on the lateral cortex of the superior articular pillar (Fig. 7). An injection of 0.3 mL of local anesthesia is given, and the needle is withdrawn 0.5 cm and a second. 0.3 mL injected to anesthetize a possible variation in the position of the C7 medial branch lateral to the process and within a small muscle tunnel in the seimispinalis capi-tis muscle, which covers the pillars (5). CT scan can also be utilized to guide the needle tip in large patients whose shoulders prevent a safe fluoroscopic approach (19).

The TON is less constant in location and thicker than the medial branches. It is lateral to the C2-C3 facet joint within the pericapsular fascia (5). This nerve can be anesthetized by the lateral approach, with the needle directed to lie on the bone at three sites along a plane perpendicular to the middle of the C2-C3 joint, cranial to the joint at the level of the tip of the superior articular process, adjacent to the superior articular cortex, and caudal to the superior articular cortex. The needle is withdrawn slightly before injecting 0.3 mL of local anesthetic to each site to avoid an intracapsular injection (Fig. 8). The posteroanterior approach requires the needle to be placed lateral to the C2-3 joint and its final position to be observed in the lateral projection (Fig. 9). Patients frequently experience temporary ataxia with this block and should be instructed to focus on objects along the horizontal until they adapt to this sensation.

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