Introduction: Several studies have explored the potential associations between radiological measurements of lumbar spine alterations and self-reported pain and disability outcomes. A recent review article has indicated that disc degeneration, spinal stenosis, and endplate lesions have high probability of relationship with low back pain and functional disability1. However, some results remain controversial. Although having multiple MRI findings was found associated with greater pain-severity, other authors recognized that degenerative changes did not correlate with pain intensity, and were not associated with pain history or long-term disability. The present study investigates the association between MRI measurements of spine alterations and self-reported outcomes of pain and disability in a population of individuals experiencing non-specific low back pain, using a comprehensive perspective based on machine learning algorithm.
Methods: A total of 246 consecutive subjects (152 females, 94 males; age ranging from 14 to 90 years) undergoing MRI scan for non-specific low back pain were prospectively assessed. Pain severity in cervical, lumbar, and leg regions was determined using visual analog scale (VAS) through a patient questionnaire. Functional disability was acquired by Oswestry Disability Index (ODI). Experienced radiologists evaluated T2-weighted sagittal and axial MRI scans of the thoraco-lumbar spine. The following alterations at the intervertebral levels from T12L1 to L5S1 were quantified: disc degeneration by Pfirrmann grading (ranging from 1 to 5)2; severity of spinal canal stenosis by Schizas grading (A, B, C, and D)3; and presence of vertebral endplate lesions based on two different classification schemes, one involving the extension of defects (six types, from Rajasekaran et al.4) and the other based on the shape (four types, from Brayda-Bruno et al.5). The measurements for each alteration were expressed as incremental integer variables. For each type of alteration, three resulting parameters were calculated: maximum value along the spinal levels, sum of values along levels, number of levels characterized by severe condition. The association between the obtained parameters of spine alterations and the self-reported outcomes (VAS and ODI) was assessed by generalized multiple linear regression model.
Results: Disc degeneration: the sum along levels and the number of levels with severe degeneration (grading>3) were found significantly associated with larger VAS (cervical and lumbar) and ODI. Spinal stenosis: sum along levels and number of levels with severe stenosis (grading=B, C, and D) were found significantly associated with larger VAS (leg) and ODI. Endplate lesions: neither of the classification schemes showed any significant associations with VAS and ODI. As regards the relation among measurements, only the two classification schemes for endplate lesions showed moderate correlation values (ranging from 0.55 to 0.75).
Discussion: The study confirmed a partial association between MRI measurements of spinal alterations and self-reported outcomes of pain and disability. Overall, disc degeneration was found to be the most correlated with the reported indexes, while spinal stenosis was shown to mainly affect the pain level in the leg region and moderately impact the disability index. As a secondary and novel finding, the study highlighted a moderate correlation between the different classification schemes for endplate lesions.