Efficacy of spinal ultrasonography just before caudal epidural block for identifying tethered cord syndrome in urological cases with sacral dimples: a retrospective descriptive study

TL;DR

Spinal ultrasound before epidural blocks can help identify tethered cord syndrome in young children with sacral dimples, potentially guiding timely surgical intervention.

Contribution

This study identifies specific sacral dimple features and filum terminale thickness as predictors of tethered cord syndrome in pediatric urological cases.

Findings

4.6% of patients required surgery for tethered cord syndrome based on spinal ultrasound and MRI findings.

Dimple long diameter ≥5 mm was significantly more common in TCS cases.

A filum terminale thickness ≥1.3 mm predicted TCS with 93% sensitivity and 80% specificity.

Abstract

Tethered cord syndrome (TCS) can be detected on spinal ultrasound (s-US) performed by anesthesiologists immediately prior to caudal epidural block. In such cases, neurosurgical consultation should be considered to ensure timely diagnosis and treatment. This study aimed to describe: (1) the frequency of TCS requiring surgery in pediatric urological cases with sacral dimples following neurosurgical consultation; (2) the sacral dimple morphology indicative of TCS; and (3) filum terminale thickness as a predictor of TCS.

This retrospective, single-center, descriptive study included children ≤ 3 years old with sacral dimples undergoing their first urological surgery with caudal epidural block between April 2019 and June 2024. We described: (1) the proportion of cases requiring spinal surgery based on s-US and postoperative magnetic resonance imaging (MRI); (2) differences in the proportions of patients with dimple long diameter ≥ 5 mm and distance from anal margin ≥ 25 mm between TCS and non-TCS cases; and (3) the optimal filum terminale thickness for predicting TCS using receiver operating characteristic curve analysis.

Among 130 patients analyzed, 6 (4.6%) underwent tethered cord release surgery based on abnormal findings from s-US and postoperative MRI. A significant difference in the proportion of patients with dimple long diameter ≥ 5 mm was identified between TCS and non-TCS cases (p = 0.046). A cutoff filum terminale thickness ≥ 1.3 mm yielded a Youden index of 0.73, with 93% sensitivity and 80% specificity for detecting filum terminale lipoma.

Spinal ultrasonography and dimple size may help to identify underlying TCS.

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