Caudal Epidural Steroid Injection: Ultrasound Guidance

Abstract

This approach utilizes ultrasound for sacral cornua identification and allows driving live under in-plane guidance into the caudal epidural space. This view is similar to a fluoroscopic lateral view but with no radiation.

Keywords

Caudal, epidural steroid injection, radiculopathy, ultrasound

Note: Please see pages ii , iii for a list of anatomic terms/abbreviations used throughout this book.

This approach utilizes ultrasound for sacral cornua identification and allows driving live under in-plane guidance into the caudal epidural space. This view is similar to a fluoroscopic lateral view but with no radiation.

In-Plane Technique ( Fig. 7C.1 )

▪

Have the patient in the prone position and place pillows under the pelvis to help with anatomic visualization.

Fig. 7C.1

A, Room and interventionalist setup for injection.

B, Ultrasound image of caudal epidural needle placement within the sacral canal in-plane or long axis. C, Drawing of relevant radiolucent structures. Yellow dashed line represents borders of the image seen on ultrasound in Fig. 7C.1A . Note the intestine in pink, which is not visible with ultrasound. D, Skeleton with the probe. Proper placement of ultrasound transducer for in-plane or long-axis placement.
▪

Ultrasound image on the opposite side as interventionist and in line with the transducer (see Fig 7C.1A and Chapter 4 ).
▪

Utilize a curvilinear transducer for patients with more posterior adipose tissue and a gel stand off for patients with limited adipose tissue (not shown).
▪

If the tissue obscures the transducer, consider taping the buttocks laterally to obtain the appropriate field for needle placement.
▪

Tent the patient’s skin prior to needle insertion.
▪

Palpate the sacral hiatus with a sterile gloved hand. This is the entry point for the spinal needle. The sacral hiatus should be palpated prior to placing the ultrasound probe.
▪

Begin with the transducer in the short axis to the sacrum, midline and proximal to the sacral hiatus, and then track distally over the two sacral cornua. The sacral cornua appear as two hyperechoic reversed U-shaped structures. In the center of the image is a hypoechoic region, the sacral hiatus, bordered by two hyperechoic bands, the sacrococcygeal ligament superiorly and the dorsal surface of the sacrum inferiorly.
▪

Rotate the transducer by 90 degrees with the long axis to the sacrum, visualizing the sacrum and sacral canal.
▪

Insert the spinal needle from caudad to cephalad into the sacral epidural space with an in-plane technique. A “pop” is felt once the sacrococcygeal ligament is pierced.
▪

Scan the needle and sacral hiatus in long and short axes to verify that the needle is traveling along the midline. The needle tip can also be directed to allow the injectate toward the more symptomatic side.
▪

The initial placement can be made in short axis, out-of-plane, and rotating 90 degrees to confirm the placement before advancing in long axis in-plane.
▪

Once the needle is advanced into the sacral canal, within the caudal epidural space, it cannot be visualized with ultrasound.