Ultrasound-guided erector spinae plane block in horses: a cadaver study

Oscar Bautista Díaz Delgado; Luis Filipe Louro; Guido Rocchigiani; Ranieri Verin; William Humphreys; Mark Senior; Ivo Campagna

doi:10.1016/j.vaa.2020.11.009

Ultrasound-guided erector spinae plane block in horses: a cadaver study

Vet Anaesth Analg. 2021 Jul;48(4):577-584. doi: 10.1016/j.vaa.2020.11.009. Epub 2021 Mar 19.

Authors

Oscar Bautista Díaz Delgado¹, Luis Filipe Louro², Guido Rocchigiani³, Ranieri Verin⁴, William Humphreys², Mark Senior⁵, Ivo Campagna⁶

Affiliations

¹ Department of Small Animal Clinical Science, University of Liverpool, Liverpool, UK. Electronic address: obautdia@gmail.com.
² Department of Small Animal Clinical Science, University of Liverpool, Liverpool, UK.
³ Department of Veterinary Pathology and Public Health, University of Liverpool, Liverpool, UK.
⁴ Department of Veterinary Pathology and Public Health, University of Liverpool, Liverpool, UK; Department of Comparative Biomedicine and Food Science, University of Padova, Padova, Italy.
⁵ Department of Equine Clinical Science, University of Liverpool, Liverpool, UK.
⁶ Department of Small Animal Clinical Science, University of Liverpool, Liverpool, UK; Department of Equine Clinical Science, University of Liverpool, Liverpool, UK.

PMID: 33934991
DOI: 10.1016/j.vaa.2020.11.009

Abstract

Objectives: To describe dye distribution and spinal nerve involvement after a simulated erector spinae plane (ESP) block performed on fresh equine cadavers.

Study design: Experimental cadaver study.

Animals: A group of 11 adult equine cadavers.

Methods: The spinal region surrounding the sixteenth thoracic vertebra (Th16) of one cadaver was removed and underwent magnetic resonance imaging. In 10 adult equine cadavers [body weight, 549 ± 58 kg (mean ± standard deviation)], 0.2 mL kg^-1 of a 50:1 2% lidocaine/dye solution was injected bilaterally (n = 20 injections) into the fascial plane between the transverse process of Th16 and the erector spinae muscles. An in-plane ultrasound-guided technique with a convex transducer was used to guide injection. Dissection was performed immediately following injection. The craniocaudal and lateral extent of dye distribution was measured (cm) and the number of vertebral bodies involved were counted (n = 20). Abdominal and thoracic cavities as well as the epidural space were also examined for presence of dye (yes/no) (n = 20). Further dissection was performed to evaluate if staining of the dorsal and ventral rami of the spinal nerves and sympathetic chain occurred (n = 14).

Results: The thoracolumbar fascia was stained in 17/20 (85%) injections and three injections terminated intramuscularly. Multisegmental staining of the dorsal rami was observed in the 14 injections in which staining was evaluated. Ventral rami staining was observed in 3/14 injections where staining was evaluated. Epidural migration was observed in 4/20 (20%) injections. No evidence of dye was found in the thoracic and abdominal cavities or on the sympathetic chain.

Conclusions and clinical relevance: The ESP block may prove beneficial to desensitize structures innervated by the dorsal rami of the thoracic spinal nerves. Further investigation is necessary to evaluate complications caused by epidural contamination.

Keywords: back pain; dorsal root; equine; nerve block; regional anaesthesia; spinal nerves.

MeSH terms

Animals
Cadaver
Horse Diseases*
Horses
Nerve Block* / veterinary
Paraspinal Muscles / diagnostic imaging
Spinal Nerves
Ultrasonography, Interventional / veterinary