Boundaries of the thoracic paravertebral space: potential risks and benefits of the thoracic paravertebral block from an anatomical perspective

Abstract

PurposeThoracic paravertebral block (TPVB) may be an alternative to thoracic epidural analgesia. A detailed knowledge of the anatomy of the TPV-space (TPVS), content and adnexa is essential in understanding the clinical consequences of TPVB. The exploration of the posterior TPVS accessibility in this study allows (1) determination of the anatomical boundaries, content and adnexa, (2) description of an ultrasound-guided spread of low and high viscous liquid.MethodsIn two formalin-fixed specimens, stratification of the several layers and the 3D-architecture of the TPVS were dissected, observed and photographed. In a third unembalmed specimen, ultrasound-guided posterolateral injections at several levels of the TPVS were performed with different fluids.ResultsTPVS communicated with all surrounding spaces including the segmental dorsal intercostal compartments (SDICs) and the prevertebral space. TPVS transitions to the SDICs were wide, whereas the SDICs showed narrowed transitions to the lateral intercostal spaces at the costal angle. Internal subdivision of the TPVS in a subendothoracic and an extra-pleural compartment by the endothoracic fascia was not observed. Caudally injected fluids spread posteriorly to the costodiaphragmatic recess, showing segmental intercostal and slight prevertebral spread.ConclusionsOur detailed anatomical study shows that TPVS is a potential space continuous with the SDICs. The separation of the TPVS in a subendothoracic and an extra-pleural compartment by the endothoracic fascia was not observed. Based on the ultrasound-guided liquid spread we conclude that the use of a more lateral approach might increase the probability of intravascular puncture or catheter position.

Assessment of an ultrasound-guided technique for catheterization of the caudal thoracic paravertebral space in dog cadavers

“…Recently, the boundaries of the TPV space have been studied in human medicine. These boundaries were the internal IIM and superior costotransverse ligament on the posterior side, the parietal PL and the endothoracic fascia in the anterolateral side and the vertebral body, intervertebral disk, and foramen in the medial side (Bouman et al, 2017). The pattern of distribution observed in our study was consistent with these findings, where the separation of the TPV space in a subendothoracic and extrapleural compartment was not observed and the TPV space had a lateral communication with the intercostal space.…”

“…None of the previous studies observed the lumbar spread of the injected solution (Monticelli et al, 2017;Portela et al, 2017;Ferreira et al, 2018). Despite this, there are previous reports attributing the origin of the psoas muscle as the caudal boundary of the TPV space in humans (Lönnqvist and Hildingsson, 1992), and recently Bouman et al (2017) showed a spread of dye into the lumbar paravertebral space. In our study, 42% of the injections within the TPV space (5/12) were distributed beyond the psoas muscle origin, reaching lumbar regions.…”

Ultrasound-guided truncal blocks for perioperative analgesia

“…Several ultrasound-guided techniques have been developed since 2009 [8][9][10][11] and although the basic procedure is still widely used [12], these ultrasound-guided techniques are now being used more frequently. The thoracic paravertebral space includes the thoracic spinal nerves, which emerge from the medial side of this space as they exit the thoracic intervertebral foramen [13]. The thoracic paravertebral space is triangular in transverse section with the medial base formed by the posterolateral aspect of the vertebral body, articular process, and intervertebral foramen [7,13,14].…”

“…The thoracic paravertebral space includes the thoracic spinal nerves, which emerge from the medial side of this space as they exit the thoracic intervertebral foramen [13]. The thoracic paravertebral space is triangular in transverse section with the medial base formed by the posterolateral aspect of the vertebral body, articular process, and intervertebral foramen [7,13,14]. The anterolateral border is formed by the parietal pleura; and the posterior border is formed by the transverse process, heads of ribs, and superior costotransverse ligament [7,13,14].…”

“…The thoracic paravertebral space is triangular in transverse section with the medial base formed by the posterolateral aspect of the vertebral body, articular process, and intervertebral foramen [7,13,14]. The anterolateral border is formed by the parietal pleura; and the posterior border is formed by the transverse process, heads of ribs, and superior costotransverse ligament [7,13,14]. The paravertebral space communicates laterally with the intercostal spaces and medially with the epidural space through the intervertebral foramen.…”