Relationship between lumbar spinal stenosis and cauda equina movement during the Valsalva maneuver

Abstract

Objective: To confirm the relationship between lumbar spinal stenosis (LSS) and cauda equina movement during the Valsalva maneuver.

Materials and methods: Two radiologists at our institution independently evaluated cauda equina movement on pelvic cine MRI, which was performed for urethrorrhea after prostatectomy or pelvic prolapse in 105 patients (99 males; mean age: 69.0 [range: 50-78] years), who also underwent abdominopelvic CT within 2 years before or after the MRI. The qualitative assessment of the cine MRI involved subjective determination of the cauda equina movement type (non-movement, flutter, and inchworm-manner). The severity of LSS on abdominopelvic CT was quantified using our LSS scoring system and performed between L1/2 and L5/S1. We calculated the average LSS scores of two analysts and extracted the worst scores among all levels.

Results: Cauda equina movement was observed in 15 patients (14%), inchworm-manner in 10 patients, and flutter in five patients. Participants with cauda equina movement demonstrated significantly higher LSS scores than those without movement (P < 0.001, Wilcoxon's rank-sum test). A significant difference was observed in the worst LSS scores between participants without movement and those with inchworm-manner movement (P < 0.001, Bonferroni's corrected). There were no significant differences between participants without movement and those with flutter movement (P = 0.3156) and between participants with flutter movement and those with inchworm-manner movement (P = 0.4843).

Conclusion: Cauda equina movement in cine MRI during the Valsalva maneuver is occasionally observed in patients with severe LSS, and may be associated with pathogenesis of redundant nerve roots.

Keywords: Cauda equina; Cine MRI; Lumbar spinal stenosis; Redundant nerve roots; Valsalva maneuver.