OBJECTIVE: To evaluate the prevalence of lumbar MRI changes associated with nerve root compression in a large, unselected middle-aged population.
SUMMARY OF BACKGROUND DATA: While degenerative spinal changes are frequently observed in imaging, their clinical relevance remains poorly understood. Furthermore, large-scale, population-based studies evaluating comprehensively the full spectrum of lumbar spine imaging variations associated with nerve root compression in MRI are lacking.
METHODS: At the age of 45-47 years, Northern Finland Birth Cohort 1966 members were invited to a follow-up. As part of the follow-up, lumbar MRI was performed on 1,534 participants in the Oulu region. Due to missing images and withdrawn consents, the final number of scanned individuals included in our study was 1,440. The following MRI changes were evaluated: disc herniations (both axial and sagittal planes), the degree of canal compromise, central and lateral recess stenoses, foraminal stenosis, spondylolisthesis and synovial cysts. Prevalences were reported descriptively.
RESULTS: The prevalence of focal protrusions across the whole lumbar spine (at least one finding at any lumbar level) was 38.2%, while broad-based protrusions accounted for 24.0%. Of the disc herniations, 11.4% were extrusions and 0.3% were sequestrations. Disc herniations were mostly central and located at disc level, and the degree of canal compromise was mild in 46.8% of the cases. The prevalence of mild changes was 99.1% in central stenosis (Grade A), 53.8% in lateral recess stenosis (Grade 1), 6.0% and 26.2% in foraminal stenosis (Grade 1, transversal and vertical perineural obliteration) and 100% in spondylolisthesis (Grade 1). Grade 2 was the highest grade of synovial cysts (prevalence of 0.3%) with no cysts of grades 3-5.
CONCLUSION: Lumbar MRI changes associated with nerve root compression were frequent, and their severity was mostly mild in general middle-aged population.
STUDY DESIGN: A cross-sectional study.
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