Novel Method for S1 Transforaminal Epidural Steroid Injection

BACKGROUND: S1 transforaminal epidural steroid injection (S1-TFESI) results in positive clinical outcomes for the treatment of pain associated with the S1 nerve root. S1-TFESI via the transforaminal approach is commonly performed under fluoroscopic guidance. Ultrasound guidance is an alternative to mitigate radiation exposure. However, performing spinal procedures under ultrasound guidance has some limitations in confirming the position of the needle tip and vascular uptake. New techniques are therefore needed to make ultrasound and fluoroscopy complementary. Our objective was to describe a novel technique for S1-TFESI and confirm its reproducibility. METHODS: Records of patients with S1 radiculopathy were reviewed retrospectively; those treated using the new S1-TFESI technique were selected. Initially, ultrasound was used to distinguish anatomy of the sacral foramen and guide initial placement of the needle entry point. Fluoroscopy was subsequently used to confirm needle tip position and vascular injection. The number of times the needle required reinsertion was recorded, and ultrasound and C-arm images were stored. RESULTS: Sixty-seven S1-TFESIs were performed in 56 patients. All injections exhibited epidural spread of contrast media, not only to the S1 nerve. The cephalad angle was 16.25 +/- 6.75 degrees (range, 5-27), the oblique angle was 2.48 +/- 2.62 degrees (range, 0-7 degrees), and the mean number of attempts was 1.24 +/- 1.25. CONCLUSIONS: The new technique, involving the use of ultrasound to guide initial placement of the needle entry point, followed by confirmatory imaging and any needed adjustment with the use of fluoroscopy, can be a technique to complement the shortcomings of using ultrasound or fluoroscopy alone.