Abstract
Introduction: Lumbar spinal stenosis (LSS) is diagnosed by a history of claudication, clinical investigation, treadmill test, and cross sectional area (CSA) in MRI or CT. Because commonly used radiological findings not always correlate with clinical symptoms, additional parameters with high specificity and sensitivity are needed.
Methods: Prospective study of dorsal lumbar nerve root sedimentation in MRI scans in supine position of 2 groups of 100 consecutive patients each between 01/2007 – 12/2007. Patients in group 1 had non-specific low back pain (LBP), no claudication, and a CSA above 120 mm2 (LBP group); patients in group 2 showed claudication with or without LBP and a CSA below 80 mm2 (LSS group). We excluded patients with a previous spine surgery. In addition to the sedimentation sign, in both groups VAS, ODI, and walking distance in the treadmill test were measured.
Results: The sedimentation sign was positive in 94 patients in the LSS group but in no patient in the LBP group, showing a specificity of 100%, a sensitivity of 94%, and an accuracy of 97%. There was no difference between segmental levels L1 – L5. Walking distance in the LSS group was shorter than in the LBP group (67 m vs. > 1000 m; p< 0.001). There were no significant differences between both groups regarding VAS and ODI.
Conclusion: In patients without LSS during MRI in supine position lumbar nerve roots sediment due to gravity to the dorsal part of the dural sac leading to a positive sedimentation sign. This sedimentation is not observed in patients with LSS. Therefore, a negative sedimentation sign is a predictor of LSS in patients without prior spine surgery with a high specificity and sensitivity. Level S1 and below were excluded in our study because nerve roots S1 and S2 leave the dural sac in a ventral position inhibiting sedimentation to the dorsal part of the dural sac. The sedimentation sign is a reliable additional diagnostic parameter in patients with LSS.
Correspondence should be addressed to: EFORT Central Office, Technoparkstrasse 1, CH – 8005 Zürich, Switzerland. Email: office@efort.org
