Cauda equina redundant nerve roots are associated to the degree of spinal stenosis and to spondylolisthesis

UNLABELLED: To evaluate the association of redundant nerve roots of cauda equina (RNRCE) with the degree of lumbar spinal stenosis (LSS) and with spondylolisthesis. METHOD: After Institutional Board approval, 171 consecutive patients were retrospectively enrolled, 105 LSS patients and 66 patients without stenosis. The dural sac cross-sectional area (CSA) was measured on T2w axial MRI at the level of L2-3, L3-4 and L4-5 intervertebral discs. Two blinded radiologists classified cases as exhibiting or not RNRCE in MRI. Intra- and inter-observer reproducibility was assessed. RESULTS: RNRCE were associated with LSS. RRNCE was more frequent when maximum stenosis<55 mm2. Substantial intra- observer agreement and moderate inter-observer agreement were obtained in the classification of RNRCE. Spondylolisthesis was identified in 27 patients and represented increased risk for RRNCE. CONCLUSION: LSS is a risk factor for RNRCE, especially for dural sac CSA<55 mm2. LSS and spondylolisthesis are independent risk factors for RNRCE.