Anatomical classification and clinical application of thoracic paraspinal blocks

Abstract

Various techniques for regional anesthesia and analgesia of the thorax are currently being used in clinical practice. A recent international consensus has anatomically classified paraspinal blocks in the thoracic spinal region into the following four types: paravertebral, retrolaminar, erector spinae plane, and intertransverse process blocks. These blocks have different anatomical targets; thus, the spreading patterns of the injectates differ and can consequently exhibit different neural blockade characteristics. The paravertebral block directly targets the paravertebral space just outside the neuraxial region and has an analgesic efficacy comparable to that of the epidural block; however, there are multiple potential risks associated with this technique. Retrolaminar and erector spinae plane blocks target the erector spinae plane on the vertebral lamina and transverse process, respectively. In anatomical studies, these two blocks showed different injectate spreading patterns to the back muscles and the fascial plane. In cadaveric studies, paravertebral spread was identified, but variable. However, numerous clinical reports have shown paravertebral spread with erector spinae plane blocks. Both techniques have been found to reduce postoperative pain compared to controls; however, the results have been more inconsistent than with the paravertebral block. Finally, the intertransverse process block targets the tissue complex posterior to the superior costotransverse ligament. Anatomical studies have revealed that this block has pathways that are more direct and closer to the paravertebral space than the retrolaminar and erector spinae plane blocks. Cadaveric evaluations have consistently shown promising results; however, further clinical studies using this technique are needed to confirm these anatomical findings.

Bolus intertransverse process block and continuous erector spinae plane block for perioperative analgesic management of video-assisted thoracoscopic surgery - Three cases report -

“…www.anesth-pain-med.org ics diffuse more reliably into the paravertebral space (Fig. 3) [5]. Therefore, we chose ITPB for single-injection blocks.…”

Regional block techniques for pain management after video-assisted thoracoscopic surgery: a covariate-adjusted Bayesian network meta-analysis.

“…On the one hand, TPVB and ESPB are significantly better than ICNB and SAPB in reducing postoperative morphine consumption, with a lower incidence of drug-induced nausea and vomiting; on the other hand, TPVB and ESPB both showed blocking effects on visceral and sympathetic nerves [ 87 ], that is, visceral related nausea and vomiting decreased, but there is no relevant evidence for ICNB and SAPB. There is solid evidence that TPVB and ESPB lead to a reduction in the incidence of clinically relevant nausea and vomiting [ 88 – 90 ]. Additionally, it has been shown that SAPB also reduced postoperative findings of nausea and vomiting compared to controls, possibly due to reduced opioid use [ 78 ].…”

Quest for the Elusive Mechanism of Action for the Thoracic Paraspinal Nerve Block Techniques. Are We Ignoring the Anatomy of the “Retro Superior Costotransverse Ligament Space?”

“…Against this backdrop of enthusiasm about the technical ease, potential safety and clinical utility of the TPSBs, and the uncertainty about their mechanism of action, 2 anatomic fascial planes in the posterior thorax 7,21,22,37,41 are rarely referred to in the TPSB literature but are noteworthy. They are the “intermuscular fat-filled fascial compartments” between the thoracic paraspinal muscles 7,31 and the “retro-SCTL space.” 21,22,37,41 These 2 anatomic spaces are interconnected, 21,22,31,41 and there is growing evidence 21,22,41 that they act as conduits for the physical spread of LA from the retro-SCTL space to the TPVS, intervertebral foramen, ES, and ICS after the TPSBs, 22,37,41 and thus warrants discussion.…”

“…Against this backdrop of enthusiasm about the technical ease, potential safety and clinical utility of the TPSBs, and the uncertainty about their mechanism of action, 2 anatomic fascial planes in the posterior thorax 7,21,22,37,41 are rarely referred to in the TPSB literature but are noteworthy. They are the "intermuscular fat-filled fascial compartments" between the thoracic paraspinal muscles 7,31 and the "retro-SCTL space."…”