Caudal Epidural Steroid Injection—Shallow Angle Approach: Fluoroscopic Guidance

Abstract

Unlike most other fluoroscopic techniques described in this atlas, there is no specific trajectory. The palpation of the sacral hiatus in combination with imaging is required to determine the proper insertion site. This technique allows driving a needle more superiorly; therefore, it may also be used to introduce a catheter through a larger bore catheter. Both anteroposterior (AP) and lateral views are utilized to avoid advancing the needle tip too far cephalad beyond the S3 level.

Keywords

back pain, caudal, epidural steroid injection, fluoroscopy, radiculopathy

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

Unlike most other fluoroscopic techniques described in this atlas, there is no specific trajectory. The palpation of the sacral hiatus in combination with imaging is required to determine the proper insertion site. This technique allows driving a needle more superiorly; therefore, it may also be used to introduce a catheter through a larger bore catheter. Both anteroposterior (AP) and lateral views are utilized to avoid advancing the needle tip too far cephalad beyond the S3 level.

Trajectory View ( Fig. 7A.1 )

No trajectory view is available for this technique.

Palpation

The physician must palpate the sacral hiatus with a gloved hand because this is the entry point for the spinal needle. Although the sacral hiatus can be fluoroscopically visualized (not shown), we recommend palpatory confirmation. The sacral cornu and sacral hiatus may not be palpable in obese patients. In such cases, the use of a hemostat to tent the skin in the midline during lateral fluoroscopy (or ultrasound use) may help define the starting point and trajectory.

Notes on Initial Needle Entry

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Note the angle of the needle that is required to enter the sacral hiatus.
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Care must be taken so that the needle correctly enters the sacral hiatus.
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The needle will need to be at an angle of at least 45 degrees or shallower to correctly enter the sacral canal.
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If the angle is too steep, the needle may potentially pass through the sacrum.
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Too steep of an entry angle is a common mistake when first performing this injection.

Optimal Needle Position in Multiplanar Imaging ( Fig. 7A.2 )

Optimal Needle Positioning in the Lateral View

A lateral view is obtained to visualize the needle angle relative to the sacral hiatus and sacrococcygeal periosteum. The use of collimation in the lateral view helps better define the image.

Lateral View Safety Considerations