The Effect of Ultrasound Guidance on Radiation Dose and Procedure Time in Lumbar Transforaminal Epidural Injection

Low back pain is one of the leading causes of disability, and its social burden and economic cost are quite high. Although there are many causes that can lead to low back pain, radicular pain, which develops mostly secondary to lumbar disc hernias, is one of the most common pathologies. Epidural corticosteroid and local anesthetic injections are an important treatment option in the treatment of lumbar radicular pain that does not respond to conservative methods.

For fluoroscopy-guided epidural injections; transforaminal, interlaminar and caudal approaches may be preferred. It is accepted as the superiority of the transforaminal approach that it allows access to the area of pathology, thus to the anterior epidural area where inflammatory mediators are more concentrated, and that it can spread to the target specifically around the inflamed nerve roots.

In transforaminal epidural injections, the use of ultrasound as the sole imaging tool throughout the entire procedure is still not appropriate, as subbony structures cannot be visualized. However, ultrasound can be integrated at any stage of the process. Thus, the relatively inexpensive cost, portability, and ability to show non-osseous tissues of ultrasonography are utilized, particularly in terms of reducing radiation exposure.

Gofeld et al. claimed that ultrasound-guided transforaminal epidural injection could be performed by targeting the posterior part of the vertebral body. However, in cases where the lamina is wide and covers the posterior of the vertebral body, it may not be possible to sonographically view the vertebral body. In addition, although the intervertebral disc is differentiated from the corpus, loss of fluid content in the elderly can cause acoustic shadowing in the disc. This may result in accidental intra-disc injections. Finally, even if the target point is reached, it is not possible to show intravascular spread at this level ultrasonographically. Therefore, in our opinion, this method is unreliable for transforaminal epidural injections. Another study used ultrasound and fluoroscopy together for transforaminal epidural injections. After imaging the lamina of the relevant vertebral level sonographically, the needle is directed to the lateral edge of the lamina, then fluoroscopic imaging is performed after it passes under the lamina with the loss of resistance technique. However, it should be known that the loss of resistance technique is not a suitable and reliable method in transforaminal injections. In addition, since it is not known how far the lamina has progressed after it has passed under the bone, in other words, imaging guidance is disabled in this part of the process.

In our clinic, we use ultrasonography and fluoroscopy methods in an integrated way (hybrid method) for transforaminal epidural injections. For this purpose, we proceed to fluoroscopic imaging immediately after the spinal needle is advanced to the lateral edge of the lamina at the vertebral level where there is pathology with ultrasound. We think that with this method, we continue to stay in the safe window and reduce the radiation dose and procedure time. Based on this, we determined the aim of this study as the effect of including ultrasonography guidance in transforaminal epidural injections on radiation dose and procedure time.