Caudal lumbar epidural injections are performed by inserting a needle through the sacral hiatus into the epidural space at the sacral canal (Figs. 68-9 and 68-10). The patient is placed in a prone position. The legs are slightly abducted and feet turned inward to separate the gluteal fold to facilitate palpation of the sacral cornu. The sacral skin is prepped and draped in a sterile manner. AP imaging can be used to visualize the location of the sacral hiatus. Alternatively, lateral imaging is used to view the bone defect, consistent with the opening of the sacral hiatus. The skin and the tissues overlying the sacral hiatus are anesthetized with 1% lidocaine. A 22- or 25-gauge spinal needle of appropriate length or a Tuohy epidural needle is inserted into the sacral hiatus. Loss of resistance can sometimes be felt upon needle penetration through the sacral ligament. Several milliliters of the contrast are injected in order to produce a sacral epidurogram to note the level that the contrast reaches. In the lateral view, a typical epidural contrast spread within the sacral canal resembles “smoke up a chimney” (Fig. 68-9), and in the AP view, it often looks like a “Christmas Tree” (Fig. 68-11). If a vascular pattern is observed, the needle should be withdrawn and redirected. Upon proper positioning, a mixture of 10 to 20 mL of solution containing 80 to 125 mg of preservative-free methylprednisolone or other equivalent doses of corticosteroid, preservative-free normal saline, and preservative-free 1% lidocaine is slowly injected into the epidural space through the spinal or epidural needle.
FIGURE 68-9. Caudal epidural injection. Needle tip in the sacral canal. Note the “smoke up the chimney” pattern of contrast in the epidural space of the sacral canal.
FIGURE 68-10. Caudal epidural injection. AP view demonstrating contrast in a “Christmas tree” pattern within the epidural space.