Facet Joint Injections

Facet Joint Injections

a as opposed to joint blocks.19-21 In the lumbar spine, patient positioning is identical to that used for facet joint injections. The approach is from posterolateral, but the target is the superior and medial-most aspect of the transverse process at the junction with the superior articular facet (Figure 11.12). The fluoroscopy tube is obliqued minimally laterally to visualize and profile the junction of the superior articular process and the transverse process of the level to be injected. Recall that each joint is supplied by two medial branches: the one just lateral to the joint of interest and the one just above. Once the anatomical target has been visualized, local anesthesia is achieved in the skin along the plane of entry. A 22-gauge spinal needle is typically used. The needle is advanced until bone is encountered, and the tube is turned to the lateral projection to confirm tip positioning at the genu between the lateral aspect of the superior articular facet and the superior aspect of the transverse process. After negative aspiration, blockade may be carried out with injection of 1.5 to 2 mL of local anesthetic with or without corticosteroid. Two medial branch block injections are required to block a single facet joint, since each joint is supplied from the medial branches of the roots above and at the level of the joint.

In the cervical spine the approach is from posterior or posterolateral. The target is the anatomical course of the medial branch along a ridge in the waist in the lateral-most and midaspect of the lateral mass (Figure 11.13). As with lumbar injections, two medial branch injections are required for blockade of one joint, injecting at the lateral masses of the

Figure 11.12. Posterior diagram of the lumbar spine showing needle positioning for medial branch blocks to affect the L4-5 joint. The needles are positioned at the expected location of the medial branches (junction of the superior articular process and transverse process) above and below the joint itself. Two medial branches are blocked owing to the dual nature of the innervation of the joint.

Figure 11.12. Posterior diagram of the lumbar spine showing needle positioning for medial branch blocks to affect the L4-5 joint. The needles are positioned at the expected location of the medial branches (junction of the superior articular process and transverse process) above and below the joint itself. Two medial branches are blocked owing to the dual nature of the innervation of the joint.

Medial Branch BlocksCervical Medial Branch Block Injection

Figure 11.13. Diagram showing the needle positioning for cervical medial branch block. In the posterior projection (A), the needles are placed against bone at the midportion of the lateral masses above and below the joint, in the expected location of the medial branch. As in the lumbar spine, two injections must be performed to fully affect one joint. In the lateral projection (B), the needle tip is typically positioned adjacent to bone with the tip of the needle approximately halfway across the bony spinal canal, well behind the vertebral body and the vertebral artery.

levels above and below the joint of interest. A 25- or 22-gauge spinal needle is advanced from a direct posterior approach to encounter bone at the lateral-most and midaspect of the lateral mass. When bone is encountered, the fluoroscopy tube is turned to the lateral position to confirm needle positioning. If necessary, the needle tip is gradually walked just off the lateral edge of the lateral mass to achieve appropriate positioning. Care should be taken to keep the needle tip positioned along a plane at the midportion of the facet joints as viewed from a lateral projection, well posterior to the course of the vertebral artery. Once positioning has been confirmed fluoroscopically, aspiration is performed to confirm placement outside the vascular compartment. A small amount of contrast material (0.2-0.5 mL) may also be injected to confirm positioning. After negative aspiration, 0.5 to 1 mL of anesthetic is injected with or without corticosteroid.

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Essentials of Human Physiology

Essentials of Human Physiology

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