Relative risk factors of nerve root sedimentation sign (Sedsign) in patients with severe central lumbar spinal stenosis (LSS)

Abstract

Here we evaluated the incidence of positive nerve root sedimentation sign (Sedsign) and its correlation with MRI parameters in patients with severe lumbar spinal stenosis (LSS) to explore its pathogenesis. Among 209 patients with severe LSS, there were 290 levels with intervertebral narrowing, among which 248 had a positive Sedsign (a prevalence of 85.52%). We then analyzed those levels with a positive Sedsign relative to those with a negative Sedsign (42 levels). There was no significant difference between the two groups for the minimum cross-sectional area (CSA) of the dural sac or the minimum posteroanterior diameter (PAD) of the spinal canal. In contrast, there was a significant difference between the groups for the grade of degenerative facet joint (DFJ) (p < 0.05), the maximum thickness of ligamentum flavum (TLF) (p < 0.01), and the maximum cross-sectional area difference (CSAD) of the dural sac (p < 0.01). In addition, receiver operating characteristic (ROC) curves were used to identify associated factors. The area under the ROC curve for PAD was 0.608 (95%CI: 0.55−0.665, p < 0.05), for DFJ was 0.634 (95%CI: 0.576−0.69, p < 0.05), for TLF was 0.74 (95%CI: 0.742−0.839, p < 0.01), and for CSAD was 0.911 (95%CI: 0.875−0.943, p < 0.01). In summary, a positive Sedsign has notable advantages in assisting with the diagnosis of severe LSS. Compression of the dural sac from the rear may be the main cause of a positive Sedsign, and the TLF and DFJ parameters were the main relative risk factors.