RESUMO
Background: The erector spinae plane (ESP) block is the most sought-after block since its inception. However, it is more of dorsal rami block with unpredictable ventral diffusion to the paravertebral area. We injected dye in ESP and other paraspinal spaces to study and compare the dye diffusion pattern along the neuroaxis and paraspinal region in human cadavers. Methods: In six soft-embalmed cadavers (12 specimens), 20 mL methylene blue dye (erector spinae plane and paravertebral space) or indocyanine green dye (inter-ligament space) was injected bilaterally using an in-plane ultrasound-guided technique at the level of the costotransverse junction of fourth thoracic vertebrae. Dye spread was evaluated bilaterally in the coronal plane in the paravertebral and intercostal spaces from the 1st and the 12th rib. Axial and sagittal sections were performed at the level of the 4th thoracic vertebrae. After cross sections, the extent of dye spread was investigated in ESP, inter-ligament, and paravertebral spaces. The staining of the ventral and dorsal rami and spread into the intercostal spaces was evaluated. Results: ESP injection was mainly restricted dorsal to the costotransverse foramen and did not spread anteriorly to the paravertebral space. The paravertebral injection involved the origin of the spinal nerve and spread laterally to the intercostal space. The inter-ligament space injection showed an extensive anterior and posterior dye spread involving the ventral and dorsal rami. Conclusions: Following ESP injection, there was no spread of the dye anteriorly to the paravertebral space and it only involved the dorsal rami. Inter-ligamentous space injection appears to be the most promising block as dye spread both anteriorly to paravertebral space and posteriorly toward ESP.
RESUMO
BACKGROUND: Novel interfascial plane blocks like PEricapsular Nerve Group (PENG) and SupraInguinal Fascia Iliaca (SIFI) blocks are effective for management of hip fracture pain. We compared the difference in the distribution of the dye injected and nerves stained by the addition of the SIFI block to the PENG block. METHODS: A total of 24 designated dye injections were performed in eight soft-embalmed cadavers. Under ultrasound guidance 20 ml green ink injected bilaterally in PENG block and 30 ml methylene blue dye was injected in the SIFI block on the right side. The cadavers were dissected 24 h later to assess the extent of dye spread. RESULTS: Extensive spread of dyes was seen on both side of iliacus muscle on the right side, but blue dye was not visible medial to the psoas tendon. The subcostal and iliohypogastric nerves were stained green in the infra-inguinal region. On the left side (PENG alone), the anterior division of the obturator, femoral and saphenous nerve (7/8) and iliohypogastric nerves (3/8) were stained in the infrainguinal region. In the suprainguinal region, the femoral nerve (5/8), accessory obturator nerve (3/8), lateral femoral cutaneous (1/8) and nerve to rectus femoris (4/8) were stained. The main obturator nerve trunk was spared with both injections while its anterior branch and accessory obturator nerve were stained with the PENG injection. CONCLUSION: The study findings indicate that combined PENG + SIFI injections lead to an extensive craniocaudal and longitudinal spread along the iliacus muscle. We perceive that the combination of these two injections will have a superior clinical outcome.
