Dermatomal coverage of single-injection ultrasound-guided parasagittal approach to anterior quadratus lumborum block at the lateral supra-arcuate ligament

The subcostal quadratus lumborum (QL) block is used in postoperative analgesia for abdominal surgery. However, only a small portion of local anesthetic can spread into the thoracic paravertebral space from the injection site via the lateral arcuate ligament, due to the barrier action of the ligament. In this study, we determined the effectiveness of a new ultrasound-guided parasagittal approach to anterior QL block at the lateral supra-arcuate ligament. Twenty six patients scheduled for laparoscopic renal surgery were enrolled. The parasagittal approach to the anterior QL block at the lateral supra-arcuate ligament was carried out preoperatively. Our data showed that at 5 and 10 min after injection, the patients achieved the sensory block of dermatomes T9–T12 and T7–L1, respectively. Some patients achieved coverage as cephalad as T5 and as caudal as L3. Four patients (16.7%) developed quadriceps weakness after the blocks. The parasagittal technique provides a new choice for postoperative analgesia of abdominal surgery with rapid onset and reliable dermatomal coverage. Trial registration: Chinese Clinical Trial Registry: ChiCTR2000029211.