A Lumbar Paravertebral Space Ultrasound Lumbar Plexus Block Technique for Hip Fracture Surgery in the Elderly.

Ultrasound imaging of peripheral nerves is challenging in elderly population. In cases involving the lumbar plexus (LP), we have employed ultrasound imaging and neurostimulation guidance for successful localization and block of the LP. The postero-medial segment of the psoas muscle (PSM), superior to the vertebral body and anterior to the transverse process ("corner pocket") was used as an imaging landmark for the implementation of the LP block. By advancing the needle through the lateral abdominal wall into the "corner pocket" we were afforded a seamless advancement of the needle into the postero-medial segment of the PSM, which is the standard anatomic position of LP in the PSM. Forty-eight patients in whom ultrasound imaging of the LP was not feasible, but the "corner pocket" was clearly depicted were included in the study. LP block characteristics and adverse events were recorded. The LP was localized in 43/48 patients. The average imaging, needling, and performance times to complete the block were 51 sec (range, 6-180 sec), 81 sec (range, 16-236 sec), and 132 sec (range, 24-270 sec), respectively. The median number of needle redirections per patient was 5.5 (range, 1-13). The local anesthetic spread was visualized in the postero-medial segment of the PSM in 39/43 patients. No complications were recorded. The imaging, needling, and performance times, as well as the number of needle passes did not significantly differ between obese and non-obese patients. In conclusion, in cases with challenging ultrasound imaging of the LP, ultrasound-assisted LP block can be accomplished through the lateral abdominal wall by using as an imaging landmark the "corner pocket" at the postero-medial quadrant of the PSM.