Multiple univariate analysis of radiologic and clinical features on 168 patients with lumbar spinal stenosis: what is the role of the erector spinae in the development of a patient’s disability?

Background: The weakening of paraspinal muscles in the paravertebral area may play a role in developing central lumbar spinal stenosis, resulting in lower back discomfort. Objective: The study thoroughly examined the correlation between the Oswestry Disability Index, Dural Sac cross-sectional area, Schizas grading Scale, Body Mass Index, and the cross-sectional areas of Erector Spinae, Multifidus, and Psoas muscles. The findings were also compared between patients with central Lumbar Spinal Stenosis and healthy individuals. Study design: Retrospective monocentric observational study. Methods: The study recruited 168 consecutive patients aged 60 or older diagnosed with central Lumbar Spinal Stenosis between January 2020 and July 2022. The patients’ condition was evaluated by administering a preoperative Oswestry Disability Index questionnaire, measuring their Body Mass Index, and performing preoperative Magnetic Resonance Imaging. The analyzed parameters were the cross-sectional area of paraspinal muscles at the L4-L5 level, dural sac cross-sectional area, and Schizas grading Scale at the most stenotic level, using multiple linear univariate analyses. Two groups of healthy individuals were recruited: Group A (under 60 years old) and Group B (over 60 years old). The same data extrapolated from these groups were compared with those of patients with central lumbar stenosis using a two-tailed Mann-Whitney test. Results: As the Erector Spinae degenerates, the Oswestry Disability Index tends to increase. Similarly, an increase in Body Mass Index is often accompanied by a decrease in the cross-sectional area of the Erector Spinae. Low dural sac cross-sectional area is statistically linked to a reduced Multifidus cross-sectional area. Interestingly, the Schizas grading scale does not appear to correlate with changes in the cross-sectional area of the paraspinal muscles. Additionally, there is no significant difference in the cross-sectional area of the Psoas muscle between individuals with central lumbar spinal stenosis and healthy individuals. Conclusions: Our study found that degeneration of the Erector Spinae plays a crucial role in the progression of perceived disability in Lumbar Spinal Stenosis. Prospective studies should investigate the long-term evolution of paraspinal muscles in decompressed patients.