Decreased catalase expression is associated with ligamentum flavum hypertrophy due to lumbar spinal canal stenosis

Background: This is an immunohistologic study of gene expression between patients and controls. This study aims to evaluate expression of the catalase gene in hypertrophied ligamentum flavum (LF) specimens obtained from patients with lumbar spinal canal stenosis (LSCS). LSCS is one of the most common spinal disorders. It is well known that LF hypertrophy plays an important role in the onset of LSCS. Although degenerative changes, aging, and mechanical stress are all thought to contribute to hypertrophy and fibrosis of the LF, the precise pathogenesis of LF hypertrophy remains unknown. Previous genetic studies have tried to determine the mechanism of LF hypertrophy. However, the association between catalase gene expression and LF hypertrophy has not yet been explored. Methods: LF specimens were surgically obtained from 30 patients with spinal stenosis (LSCS group) and from 30 controls with lumbar disc herniation (LDH group). LF thickness was measured at the thickest point using calipers to an accuracy of 0.01 mm during surgical intervention. The extent of LF elastin degradation and fibrosis were graded (grades 0–4) by hematoxylin and eosin staining and Masson trichrome staining, respectively. The resulting LF measurements, histologic data, and immunohistologic results were then compared between the 2 groups. Results: The average LF thickness was significantly higher in the LSCS group than in the LDH group (5.99 and 2.95 mm, respectively, P = .004). Elastin degradation and fibrosis of the LF were significantly more severe in spinal stenosis samples than in the disc herniation samples (3.04 ± 0.50 vs 0.79 ± 0.60, P = .007; 3.01 ± 0.47 vs 0.66 ± 0.42, P = .009, respectively). Significantly lower expression of catalase was observed in the perivascular area of LF samples obtained from patients with LSCS compared with controls (61.80 ± 31.10 vs 152.80 ± 41.13, respectively, P = .009). Conclusion: Our findings suggest that decreased expression of catalase is associated with LF hypertrophy in patients with LSCS. Copyright © 2019 the Author(s). Published by Wolters Kluwer Health, Inc.