Correlation Between Dural Sac Size in Dynamic Magnetic Resonance Imaging and Clinical Symptoms in Patients with Lumbar Spinal Stenosis

Abstract

Objective: To assess the dynamic change of the dural sac size in patients with lumbar spinal stenosis (LSS) from supine to standing position and their correlation with clinical symptoms.

Methods: A total of 110 patients with LSS were prospectively enrolled to undergo both supine (0°) and standing (78°) magnetic resonance imaging (MRI). Dural sac cross-sectional area (DCSA) and dural sac anteroposterior diameter (DAPD) at the most constricted spinal level in supine and standing MRI were measured and compared. Clinical symptoms were assessed by duration of disease, claudication distance, visual analog scale (VAS) score of leg pain, and Chinese Oswestry Disability Index score of low back pain. The correlation between the parameters and clinical symptoms was analyzed by Pearson correlation coefficient (r).

Results: Mean minimum DCSA and DAPD in the standing position were significantly smaller (both P < 0.01) than in the supine position. DCSA and DAPD in standing MRI and their changes had better correlation with the intermittent claudication distance and VAS score of leg pain than in the supine position. A more than 15 mm² reduction of DSCA was observed in patients with shorter claudication distance and more severe VAS score of leg pain (both P < 0.01).

Conclusions: Dural sac size on MRI was reduced significantly from supine to standing position. Standing MRI and the changes of DCSA significantly correlated with claudication distance and VAS score of leg pain in patients with LSS. Therefore, standing MRI provides more radiologic information correlating with clinical symptoms in patients with LSS than supine MRI.

Keywords: Claudication distance; Correlation; LSS; Standing MRI; VAS of leg pain.