Comparison of the Skin-to-Epidural Space Distance at the three Thoracic levels in Children using Magnetic Resonance Imaging for Epidural Anesthesia

Abstract

Background: Several ways were used to assess the distance from the skin to the epidural space, with the aim of increasing the success of the technique. MRI is the most significant technological advancement in the diagnostic examination of the pediatric spine. The aim of this study was to evaluate the distance between the skin and the epidural space through MRI at three thoracic segments in children aged 0 to 13 years. Methods: Retrospective study with 105 children aged 0 to 13 years in the supine position underwent MRI, and the 2nd, 5th, and 10th thoracic segments were measured. The following parameters were evaluated: skin and the epidural space; needle entry angle between the skin and intervertebral space; and distance corrected by an angle between skin and the epidural space. To compare the proposed data between the samples, we used the Kruskal-Wallis test. The Kruskal-Wallis rank test is a non-parametric method for testing whether samples come from the same distribution. Results: This study evaluated 60 male and 45 female children. The mean distance between Skin-EpiS was 29.27 mm at T2, 26.52 mm at T5, and 24.28 mm at T10, with a significant difference, being the greatest distance found in T2. The Skin-EpiS at T10 was shorter than the other two measurements. Regarding needle entry angle between skin and the three intervertebral spaces, the smallest angle was observed (T2=27.16º) significantly smaller than in the other two spaces (T5=38.68º, T10=39.08º). However, this difference in angle did not result in a significant difference in the distance between the skin and epidural space corrected by the entry angle in the three intervertebral spaces, being practically the same, T2=33.0 mm, T5=34.60 mm, T10=32.1 mm. Conclusion: Precise Skin-EpiS distance information can facilitate accurate needle placement in children’s epidural space and thus decrease the risk of complications. This study in children aged 0 to 13 years provided important information for performing single shots or continuous thoracic epidurals, reducing the potential for complications during its performance.