Papers of the Week

Many techniques for regional anesthesia and analgesia of the thorax are currently being used in clinical practice. Among them, a recent international consensus anatomically classified paraspinal blocks in the thoracic spine region into four different types: paravertebral block, retrolaminar block, erector spinae plane block, and intertransverse process block. These blocks have different anatomical targets, thus the spreading patterns of the injectate differ. Consequently, they can have different neural blockade characteristics in patients. Paravertebral block directly targets the paravertebral space just outside of the neuraxial region and has comparable analgesic efficacy to epidural block. However, there still remains the potential risks of this technique during the procedure. Retrolaminar and erector spinae plane blocks target the erector spinae plane on the vertebral lamina or transverse process, respectively. In anatomical studies, these two blocks showed different spreading patterns of injectate to the back muscles and fascial plane. Paravertebral spreading occurred but was variable in cadavers. However, numerous clinical reports support potential paravertebral spread when using erector spinae plane blocks. Both techniques reduced postoperative pain compared to the control, but results were inconsistent compared to those obtained with paravertebral block. Intertransverse process block targets the tissue complex posterior to the superior costotransverse ligament. Anatomical studies have revealed that the target area of this block has more direct and closer pathways to the paravertebral space than those of retrolaminar and erector spinae plane blocks. Cadaveric evaluations have consistently shown promising results, but further clinical studies are needed to confirm anatomical findings using this technique.