Anatomical description of anaesthetic spread after deep erector spinae block at L-4.
INTRODUCTION
Thoracic erector spinae plane (ESP) block is now used for postoperative analgesia. However, although reports of lumbar ESP have been published, the anesthetic spread and mechanism of action of this technique remains unclear. We describe the lumbar ESP block technique and evaluate the spread of 20ml of solution administered at the level of the transverse process of L4 in a cadaver model.


METHODS
Observational study after 12 lumbar ESP blocks at L4 on a fresh cadaver model (6 bilaterally). The spread of 20ml of injected contrast solution was assessed by computed tomography in all 6 samples. Four of the samples were evaluated by anatomical study, 2 by plane dissection, and 2 others were frozen and cut into 2-2.5cm axial slices.


RESULTS
The injected solution spread from L2 to L5 in a cranio-caudal direction in the erector spinae muscle, reaching the facet joints medially and the thoracolumbar fascia laterally. In 33% of cases the solution did not spread anterior to the transverse process; in 51%, spread was minimal and did not affect the corresponding spinal nerves, and in 2 samples (16%), spread was extensive and reached the corresponding spinal nerves.


CONCLUSIONS
Lumbar ESP at L4 always acts on the posterior branches of the spinal nerves, but seldom spreads to the paravertebral space to block the spinal nerve.
['De Lara González|S J|SJ|', 'Pomés|J|J|', 'Prats-Galino|A|A|', 'Gracia|J|J|', 'Martínez-Camacho|A|A|', 'Sala-Blanch|X|X|']
D000777:Anesthetics D002102:Cadaver D004396:Coloring Agents D004058:Diffusion D005205:Fascia D006801:Humans D021621:Imaging, Three-Dimensional D007267:Injections D008159:Lumbar Vertebrae D008751:Methylene Blue D018482:Muscle, Skeletal D009407:Nerve Block D010149:Pain, Postoperative D013127:Spinal Nerves D013904:Thoracic Vertebrae D014057:Tomography, X-Ray Computed D014463:Ultrasonography D021801:Zygapophyseal Joint
Anatomy: L4 transverse process Anatomía: transversa L4 Anesthesia spread Bloqueo plano del erector espinal Distribución anestésica Dorsal rami of the spinal nerves Erector spinae plane block Ramo dorsal del nervio espinal