Magnitude of dural tube compression does not show a predictive value for symptomatic lumbar spinal stenosis for 1-year follow-up: a prospective cohort study in the community

BACKGROUND: The North American Spine Society states that lumbar spinal stenosis (LSS) is a clinical syndrome, and there is insufficient evidence to make a recommendation for or against a correlation between clinical symptoms or function and the presence of anatomic narrowing of the spinal canal on MRI. The main purpose of this study was to assess the influence of the magnitude of dural tube compression on MRI on LSS symptoms at the cross-sectional and 1-year follow-up. METHODS: This was a prospective cohort study of 459 participants who were assessed for LSS using a questionnaire and conventional MRI of the lumbar spine. After 1 year, 335 subjects (follow-up rate 73.0%) were assessed for LSS using the same questionnaire. The time course of the clinical subjective symptoms of LSS and the relationship between the said symptoms of LSS and magnitude of dural tube compression on MRI were analyzed in a cross-sectional and longitudinal fashion. RESULTS: 1) The dural sac cross-sectional area (DCSA) decreased with age. 2) Severe dural tube compression had a strong influence on the presence of symptomatic LSS; however, 40%–70% of participants with severe dural tube compression did not show clinical symptoms of LSS. 3) At the 1-year follow-up, >50% of the LSS-positive participants in the initial year were reclassified as LSS negative, and 10% of the LSS-negative participants were reclassified as LSS positive. 4) The magnitude of the DCSA on MRI did not directly affect the presence of LSS at the 1-year follow-up. CONCLUSION: LSS symptoms were changeable. Anatomical dural tube compression on MRI did not predict the presence of clinical LSS symptoms at the 1-year follow-up.