Hypothesis

Lumbar spinal stenosis (LSS) is diagnosed by a history of claudication, clinical investigation, cross-sectional area (CSA) of the dural sac on MRI or CT, and walking distance on the treadmill test. As radiological findings do not always correlate with clinical symptoms, additional diagnostic signs are needed. In patients without LSS, we observe the sedimentation of lumbar nerve roots to the dorsal part of the dural sac on supine MRI scans. In patients with LSS, this sedimentation is rarely seen. We named this phenomenon ‘sedimentation sign’ and defined the absence of sedimenting nerve roots as positive sedimentation sign for the diagnosis of LSS. We hypothesised that the new sedimentation sign discriminates between non-specific low back pain (LBP) and LSS.