Magnetic resonance imaging findings and their relationships in the thoracic and lumbar spine. Insights into the etiopathogenesis of spinal degeneration.

Study Design Descriptive epidemiologic study about magnetic resonance imaging findings in the spine. Objectives To describe the prevalence of magnetic resonance imaging findings in a general population at spinal levels T6-S1, and to examine the relationships of these findings within each spinal level and between levels. Summary of Background Data The prevalence of specific findings and the associations between findings and spinal levels can provide general insights into the etiopathogenesis of spinal degeneration. Methods Subjects consisted of 232 men from a population sample (mean age 49.3 years). Signal intensity, disc bulging, disc herniation, and endplate irregularities were among 11 findings assessed from magnetic resonance images. Results The disc signal intensities were assessed to be lowest in the lumbar and middle thoracic regions. Disc bulging and disc height narrowing were most common in the lower levels of both the thoracic and lumbar regions. All magnetic resonance imaging findings except herniations and endplate irregularities were clearly associated with age. Osteophytes were most highly associated with disc bulging in levels T6-L3, and with endplate irregularities in the lower lumbar levels. Disc herniations were not consistently associated with any other findings. The disc levels that most highly correlated are grouped as follows: T6-T10, T10-L4, and L4-S1. Conclusions With the exception of endplate irregularities and herniations, the magnetic resonance imaging findings appeared to be associated with the same pathogenic process. The interaction of mechanical factors and spinal structures varies between spinal levels, and the degeneration common in the lower parts of the thoracic and lumbar spine could be an outcome of vulnerability for torsional forces. Some gross guidelines for grouping findings can be drawn from disc level correlations.