Spread of Quadratus Lumborum Block to the Paravertebral Space Via Intramuscular Injection: A Volunteer Study

Background and Objectives Several types of quadratus lumborum block (QLB) are used for postoperative analgesia and are believed to be effective against both somatic and visceral pain via a local anesthetic (LA) effect in the paravertebral space (PVS). However, it remains unclear whether all QLB techniques result in LA spread into the PVS. We hypothesized that LA administered via intramuscular QLB would spread into the paravertebral space and investigated the spread and sensory block area of LA in intramuscular QLB. Methods This volunteer study included 5 healthy men and 1 woman, with no previous medical history. Intramuscular QLB and lateral transversus abdominis plane block were performed under real-time ultrasound guidance for comparison of sensory deprivation range. Two days later, the same procedure was performed on the contralateral side of the body. The spread of LA via intramuscular QLB spread to the PVS was assessed 1 hour after the first injections using magnetic resonance imaging. Sensory perception was also evaluated by the pinprick test at 90 minutes after injection. Results In total, we performed 11 intramuscular QLBs and 11 lateral transversus abdominis plane blocks. Magnetic resonance imaging showed that LA did not spread into the PVS after ultrasound-guided intramuscular QLB. The analgesic area corresponded to the side of the body that was ipsilateral to the block. Conclusions Ultrasound-guided intramuscular QLBs are not clinically useful for procedures requiring LA spread into the PVS but do result in an ipsilateral analgesic effect in healthy volunteers. Clinical Trial Registration This study was registered at University Hospital Medical Information Network Clinical Trials Registry, UMIN 000019149. Accepted for publication October 4, 2017. Address correspondence to: Takahiro Tamura, MD, PhD, Department of Anesthesiology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-Ku, Nagoya 466-8550, Japan (e-mail: takahiro@med.nagoya-u.ac.jp). Nagoya University Graduate School of Medicine and Japanese Red Cross Nagoya Daiichi Hospital funded this study by providing funding to the Department of Anesthesiology, Nagoya University Graduate School of Medicine, Nagoya, Japan. This work was presented in part at the American Society of Anesthesiologists' Anesthesiology 2016 meeting; Chicago, IL; October 22 to 26, 2016. The authors declare no conflict of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.rapm.org). Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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