Changes in cross-sectional area of psoas major muscle in unilateral sciatica caused by disc herniation

Abstract

Study design: A clinical prospective cohort study of 15 healthy volunteers and 25 patients with unilateral sciatica from single-level disc herniation.

Objectives: To detect any changes in the cross-sectional area of the psoas major muscle in patients with single-level (lateral to mediolateral) disc herniation causing unilateral sciatica.

Summary of background data: The exact role of the psoas major muscle in the origin of low back pain and sciatica has not been clarified.

Methods: Fifteen healthy volunteers and 25 patients with unilateral sciatica from single-level disc herniation were subjected to magnetic resonance imaging of the lumbar spine. The cross-section area of the psoas major muscle on either side was recorded, and differences were noted. In patients, the cross-section area of either side was compared with and duration of sciatica was related to changes in the cross-section area.

Results: Insignificant variation in the cross-section area of the psoas major was observed in volunteers. In the patient group, significant reduction in the cross-section area of the psoas major was observed at the level and the site of the disc herniation. A significant correlation between cross-section area of the psoas major and ipsilateral continuous sciatica was found. There was no relation between the reduction of the cross-section area and the amount of disc herniation.

Conclusion: The cross-section area of the psoas major is ipsilaterally decreased in unilateral lumbar disc herniation. The reduction in cross-section area is positively correlated with the duration of continuous sciatica.