Background and objectives The erector spinae plane (ESP) block is a relatively new interfascial block technique. Previous cadaveric studies have shown extensive cephalocaudal spread with a single ESP injection at the thoracic level. However, little data exist for lumbar ESP block. The objective of this study was to examine the anatomical spread of dye following an ultrasound-guided lumbar ESP block in a human cadaveric model.
Methods An ultrasound-guided ESP block was performed in unembalmed human cadavers using an in-plane approach with a curvilinear transducer oriented longitudinally. 20 mL of 0.166% methylene blue was injected into the plane between the distal end of the L4 transverse process and erector spinae muscle bilaterally in four specimens and unilaterally in one specimen (nine ESP blocks in total). The superficial and deep back muscles were dissected, and the extent of dye spread was documented in both cephalocaudal and medial–lateral directions.
Results There was cephalocaudal spread from L3 to L5 in all specimens with extension to L2 in four specimens. Medial–lateral spread was documented from the multifidus muscle to the lateral edge of the thoracolumbar fascia. There was extensive dye in and around the erector spinae musculature and spread to the dorsal rami in all specimens. There was no dye spread anteriorly into the dorsal root ganglion, ventral rami, or paravertebral space.
Conclusions A lumbar ESP injection has limited craniocaudal spread compared with injection in the thoracic region. It has consistent spread to dorsal rami, but no anterior spread to ventral rami or paravertebral space.
- lower extremity
- nerve block
- regional anesthesia
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Contributors Study design/planning: MWH, DPS, NRL, VK, MBK. Data acquisition, analysis, interpretation, writing manuscript, revision and approval of final manuscript: all authors.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was deemed exempt by the Mayo Clinic Institutional Review Board and was approved by the Mayo Clinic Biospecimens Subcommittee (IRB#19-008419, Bio00017871).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.