Visualization of Needle-Tip Localization by Ultrasound Guidance with Contrast Bubble in Lumbar Selective Nerve Root Block: Clinical Pilot Study

Background: Epidural steroid injection for low back and leg pain has been shown to result in a positive clinical outcome. Lumbosacral selective nerve root block (SNRB) via a transforaminal approach is commonly performed under fluoroscopic guidance. However, ultrasound guidance is an alternative to overcome the radiologic disadvantages. This study examined the accuracy of needle-tip localization under ultrasound guidance with a contrast bubble, compared with fluoroscopic guidance. Objective: The primary objectives were to envisage the needle-tip localization with an air bubble by ultrasound and also to determine the accuracy of needle-tip location in transforaminal lumbar SNRB for low back and leg pain patients who were not surgical candidates. Methods: A prospective study of 30 SNRBs was conducted. An air bubble was produced and was used to envisage the needle-tip location under ultrasound guidance. Finally, the needle tip was confirmed by fluoroscopy. The accuracy of needle-tip location was statistically analyzed. Results: Twenty-four SNRBs were performed at L4–5 and 6 SNRBs at L3–4. The accuracy of needle-tip localization was 80%. Conclusion: In order to avoid radiation exposure during the SNRB procedure, ultrasound guidance might be an alternative. Despite being accepted practice, there is a steep learning curve involved in the use of ultrasound guidance for lumbar SNRB, and proper training is crucial. A contrast bubble is a prospective enhancement for better visualization of ultrasound guidance.