The dural sac spiking sign: predictive significance of magnetic resonance imaging-detected dural morphological abnormalities for dural tears in lumbar burst fractures.

BACKGROUND CONTEXT

Magnetic resonance imaging (MRI) is the most valuable modality for diagnosing soft tissue lesions of the spine. However, MRI has limited ability to predict preoperatively whether lumbar burst fractures are combined with dural sac tears.

PURPOSE

The objective is to identify preoperative MRI signs that can be used to predict the occurrence of dural sac tears in lumbar burst fractures. The aim is to establish and validate a proprietary MRI axial sign, the dural sac spiking sign, for the detection of dural sac tears.

STUDY DESIGN

A Single-center retrospective case-control study.

PATIENT SAMPLE

We retrospectively analyzed 35 patients with lumbar burst fractures who underwent posterior spinal canal exploration between January 2012 and May 2024 at our institution, and characteristic axial MRI sign (the dural sac spiking sign) was observed in 11 of 12 patients with dural tears. Oustcome measures. The dural sac spiking sign.

METHODS

In this study, 1076 patients with thoracolumbar spine admitted between January 2012 and May 2024 were retrospectively collected. Based on the inclusion and exclusion criteria, 35 patients were screened for analysis and statistics. The patients were divided into two categories based on the presence or absence of intraoperative dural sac tears: one with dural sac tears and the other with intact dural sac. The following patient demographic information, preoperative clinical data, and MRI imaging parameters were collected: the presence of laminar fractures, the angle of the retropulsed segment, the rate of epidural fat encroachment, the rate of spinal canal cross-sectional area (CSA) encroachment, the rate of dural sac CSA encroachment, and the abnormal morphological findings of the dural sac (The dural sac spiking sign). Furthermore, correlation, mediation, and receiver operating characteristic (ROC) curve analyses were performed. Meanwhile, binary logistic stepwise regression was employed to identify the independent risk factors associated with dural sac tears detected on MRI.

RESULTS

A total of 35 patients were included in this study, consisting of 12 females (34.3%) and 23 males (65.7%). The mean age of the participants was 39.03 years (range: 16-55 years). Dural sac tears were not found to be statistically different with respect to gender, age, BMI, the rate of spinal canal cross-sectional area (CSA) encroachment, or the rate of dural sac CSA encroachment. The occurrence of dural sac tears was significantly influenced by several factors, including the dural sac spiking sign (P < 0.001), laminar fractures (P = 0.015), preoperative neurological deficit (P = 0.015), the angle of the retropulsed segment (P < 0.001), and the rate of epidural fat encroachment (P < 0.001). The findings indicate that the dural sac spiking sign exerts a mediating influence between the angle of the retropulsed segment, the rate of epidural fat encroachment, and the occurrence of dural sac tears. The results of the binary logistic stepwise regression analysis demonstrated that the dural sac spiking sign (OR = 242, P < 0.001; 95% CI 13.79-4245.78) is an independent risk factor for dural sac tears in patients with lumbar burst fractures. The receiver operating characteristic (ROC) curve analyses indicated that the MRI dural sac spiking sign (AUC = 0.937; 95% CI 0.833-1.041; P < 0.001) is a reliable predictive indicator of dural sac tears in patients with lumbar burst fractures, with a sensitivity of 91.7% and a specificity of 95.7%.

CONCLUSIONS

The dural sac spiking sign on axial MRI imaging may serve as a radiographic marker for dural tears in lumbar burst fractures. When combined with neurological assessment and fracture morphology evaluation, this sign enhances preoperative recognition of dural injury risks, enabling tailored surgical planning and meticulous decompression to reduce iatrogenic neural injury during intervention.