Ultrasound-guided Pararadicular Injection in the Lumbar Spine: A Comparative Study of the Paramedian Sagittal and Paramedian Sagittal Oblique Approaches.

BACKGROUND

Ultrasound-guided nerve root blocks and transforaminal injections are well established, and several procedural feasibility studies have been reported. However, the contrast dispersion pattern during ultrasound-guided pararadicular injection has not been reported. We hypothesized that the paramedian sagittal oblique approach provides a superior intraforaminal contrast-spread pattern compared to the paramedian sagittal approach during ultrasound-guided pararadicular injections in the lumbar spine.

METHODS

Ninety injections were performed in 42 adult patients using pararadicular injections. Each injection was allocated to 1 of 2 groups. In the paramedian sagittal approach group, the transducer was positioned perpendicularly over the skin, and a bent needle was inserted using an in-plane technique. In the paramedian sagittal oblique approach group, the needle was advanced with the transducer tilted ~20 to 25° toward the pararadicular aditus plane. In both groups, the needle was advanced until the intertransverse ligament was punctured. Nonionic contrast media was injected under fluoroscopic guidance.

RESULTS

The contrast was injected in the targeted pararadicular compartment in 83 of 90 injections (92.2%). Among the successful pararadicular injections, the intraforaminal contrast pattern was detected in 17 cases (39.5%) in the paramedian sagittal approach group and in 35 cases (87.5%) in the paramedian sagittal oblique approach group (P < 0.001). Both groups showed significant pain reduction compared to the baseline (P < 0.001); however, the visual analog scale for pain showed significantly lower pain in the paramedian sagittal oblique approach group compared to the paramedian sagittal approach group (P = 0.036). Rates of ventral epidural flow, intra- and extraepineural pattern of contrast, and intravascular injections were similar between the two approaches.

CONCLUSION

The paramedian sagittal oblique approach delivered a superior intraforaminal contrast-spread pattern and significantly greater pain relief than the paramedian sagittal approach during ultrasound-guided pararadicular injections in the lumbar spine.