# 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.

## Key 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.