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.

中文翻译：

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超声引导下的马竖脊肌平面阻滞：一项尸体研究

目标

描述对新鲜马尸体进行模拟竖脊肌平面 (ESP) 阻滞后的染料分布和脊神经受累。

学习规划

实验尸体研究。

动物

一组 11 具成年马尸体。

方法

一具尸体的第十六胸椎（Th16）周围的脊柱区域被移除并进行了磁共振成像。在 10 具成年马尸体 [体重，549 ± 58 kg（平均值 ± 标准偏差）] 中，将 0.2 mL kg ^–1的 50:1 2% 利多卡因/染料溶液双侧注射（n  = 20 次注射）至筋膜平面Th16 横突与竖脊肌之间。使用具有凸面换能器的平面内超声引导技术来引导注射。注射后立即进行解剖。测量染料分布的颅尾和横向范围（cm）并计算所涉及的椎体数量（n = 20）。还检查了腹腔和胸腔以及硬膜外腔是否存在染料（是/否）（n  = 20）。进行进一步解剖以评估脊神经和交感神经链的背侧和腹侧支是否发生染色（n  = 14）。

结果

胸腰筋膜在 17/20 (85%) 注射中染色，3 次肌肉注射终止。在评估染色的 14 次注射中观察到背支的多节段染色。在评估染色的 3/14 次注射中观察到腹侧支染色。在 4/20 (20%) 注射中观察到硬膜外迁移。在胸腔和腹腔或交感神经链上没有发现染色的证据。

结论和临床相关性

ESP 阻滞可能证明有利于使受胸脊神经背支支配的结构脱敏。需要进一步调查以评估硬膜外污染引起的并发症。