The anatomical features of an ultrasound-guided erector spinae fascial plane block in a cadaveric neonatal sample

Background: Since its inception, the erector spinae plane block has been used for a variety of truncal surgeries with success in both adults and children. However, the anatomical features, route of spread, and dermatomal coverage are still not fully understood in a pediatric population. Objectives: To identify the anatomical features of the erector spinae fascial plane space by replicating an erector spinae plane block in a fresh neonatal cadaveric sample. The primary aim was to determine the spread of the dye within the fascial plane, while the secondary aims were to determine whether the needle direction or entry site affected the spread. Methods: The block was replicated bilaterally using 0.1 mL/kg of iodinated contrast dye in nine fresh unembalmed preterm neonatal cadavers. The dye was introduced under ultrasound guidance at vertebral level T5 and T8. Additionally, the needle was oriented cranial-caudal vs caudal-cranial to determine if the needle orientation influenced the spread of dye. The block was also replicated midway between the adjacent transverse processes as opposed to the lateral tip of the transverse process to determine the spread. Results: From the total sample size, 14 “blocks” were successfully replicated, while 4 “blocks” were either incomplete or failed blocks. Contrast dye was found in the paravertebral, intercostal, and epidural spaces, including posteriorly over the neural foramina. Results revealed that the needle direction or entry site did not influence the spread within the fascial plane. Conclusion: Contrast material was found in the paravertebral, epidural, and intercostal spaces over an average of 5 vertebral levels when using 0.1 mL/kg.