Medical Student Columbia University Vagelos College of Physicians and Surgeons
Disclosure(s):
Terrence C. Green, B.S.: No financial relationships to disclose
Introduction: Fatty infiltration within paraspinal muscles has been linked to various spinal pathologies, but its relationship with spinal stenosis remains underexplored. Emerging evidence suggests that compensatory mechanisms between the posterior paraspinal muscles and the psoas may influence degeneration patterns. Investigating fatty infiltration and these relationships could provide valuable insights into the underlying processes of spinal degeneration.
Methods: We conducted a retrospective analysis of lumbar spine MRIs. Paraspinal muscles were segmented using 3D Slicer’s TotalSegmentator, followed by semi-manual refinement to isolate the erector spinae, multifidus, and psoas major. Otsu thresholding was applied to differentiate muscle and fat content. Muscle integrity (total volume, fat volume, and muscle volume) and fatty infiltration (FI) were quantified, with FI calculated as the ratio of fat volume to total volume (muscle and fat combined).
Results: A total of 92 patients were assessed: 50 controls with no evidence of degenerative spinal pathology and 42 with spinal stenosis between L1-L5. In the stenosis group, 16 patients had involvement at L3-L4 and 22 at L4-L5. At L3-L4, stenosis patients had significantly higher psoas muscle volume (p < 0.05), lower psoas fat volume (p < 0.005), and lower fatty infiltration (p < 0.001) compared to controls. At L4-L5, there was significantly elevated fatty infiltration in the multifidus and increased fat volume in both the erector spinae and multifidus compared to controls (p < 0.05). Across L1-L5, higher fatty infiltration in the multifidus and erector spinae was associated with increased stenosis grades (p < 0.05).
Conclusion : Our findings reveal statistically significant muscle size changes and fatty infiltration in the paraspinal muscles of stenosis patients. Further research is needed to expand upon these preliminary associations and deepen the understanding of muscle composition in degenerative lumbar spinal pathology.