Real-time sonographic imaging for periradicular injections in the lumbar spine: a sonographic anatomic study of a new technique.

OBJECTIVE: We conducted this study to develop a sonographically guided approach to the spinal nerve of the lumbar spine and to assess its feasibility and accuracy by means of computed tomography (CT). METHODS: Fifty sonographically guided approaches at 5 levels (L1-S1) were performed on 5 embalmed cadavers, which were positioned prone. The spinal nerves of the lumbar spine were shown under sonographic guidance. In 1 cadaver, the most lateral aspect of the roof of the intervertebral foramen was defined as a reference point. Its position was computed as a distance from the tip of the spinal process (A), the midline (B), and the intervertebral disk (C). Subsequently, axial transverse CT scans were made to verify these distances. In a second part of the experiment, a spinal needle was advanced under sonographic guidance to the spinal nerves for each lumbar spinal level on 1 embalmed cadaver. The exact placement of the needle tips was checked with the help of CT. RESULTS: This technique for a sonographically guided approach to the periradicular area proved to be feasible and accurate. Sonography and CT provided the same mean measurements of 4.0, 2.5, and 1.4 cm for distances A, B, and C, respectively. The Pearson correlation coefficient was 0.99 (P < .001) between sonography and CT. In the experimental study, all 10 needle tips were placed periradicular to the spinal nerves. CONCLUSIONS: Sonographic guidance is a useful adjunct to increase the safety and efficacy of periradicular injections in the lumbar spine.