Dural Sac Cross-Sectional Area Measurement as an Indicator of Cauda Equina Syndrome Risk in Patients with Lumbar Disc Herniation.

Background/Objectives: Cauda equina syndrome (CES) is a rare but severe complication of lumbar disc herniation (LDH). This study aimed to assess the diagnostic value of the dural sac cross-sectional area (DSCSA) in predicting CES in affected patients. Methods: In this retrospective observational study, we analyzed 99 patients who underwent surgery for LDH, including cases with CES, between 2014 and 2023. The DSCSA was measured at the narrowest level of the dural sac using axial T2-weighted magnetic resonance imaging. Univariable and multivariable logistic regression were performed on DSCSA and other candidate risk factors. Results: Among the patients with LDH, nine (9.1%) had CES. In multivariable logistic regression, DSCSA was associated with CES, with an adjusted odds ratio of 0.79 (95% confidence interval [CI]: 0.62-0.90, p = 0.011). Exploratory receiver operating characteristic analysis identified an optimal DSCSA cut-off of 31.16 mm2, yielding 100% sensitivity, 92.2% specificity, and an area under the curve of 0.974 (95% CI: 0.944-1.000, p < 0.001). Conclusions: Smaller DSCSA was associated with CES in patients with LDH. Patients with a DSCSA of approximately 30 mm2 or less may require closer monitoring for the development of CES symptoms. Given the limited number of CES cases, these findings should be interpreted cautiously and validated in larger studies.