Pilot Study of the Dynamic Effects of Simulated Axial Loading Magnetic Resonance Imaging in Lumbar Disc Herniation

ABSTRACT

Study Design: A pilot study of lumbar disc herniation patients examined with magnetic resonance imaging in both psoas-relaxed position and axial compression in extension of the lumbar spine is described. Objective: To discuss the clinical value of axially loaded magnetic resonance imaging in patients with lumbar disc herniation and to evaluate the effect on the dural cross-sectional area. Summary of Background Data: Magnetic resonance imaging tests are performed in a supine relaxed position. It is well documented that a narrowing of the spinal canal is provoked by axial loading, especially when it is combined with spinal extension. Physiological or pathological changes due to loading effects might thus remain undetected by conventional imaging tests. This unloading effect could lead surgeons to a diagnosis that does not take into account these dynamic aspects. The present pilot study seeks to evaluate the effect of axial loading compression on the dural cross-sectional area in patients with lumbar disc herniation. The purpose of this study is to help surgeons in making treatment decisions or surgery indications. Methods: 15 patients underwent magnetic resonance imaging examinations in both psoas-relaxed position and axial compression in extension using a compression device (DynaWell®). An axial load corresponding to 50% of the body weight was applied. Changes in the dural cross-sectional area were registered. Results: A significant decrease in dural cross-sectional area was found in only 2 patients (13.3%). In 13 patients, no significant changes in dural cross-sectional area were found. Concerning the overall results, no significant differences were observed between both MRI. Conclusions: Using magnetic resonance imaging, no statistical significant decrease in dural cross-sectional area after axial loading was found. These findings do not support the recommendation of magnetic resonance imaging with axial compression in patients with sciatica secondary to lumbar disc herniation.

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