5.2. Correlations of symptoms and signs to MRI findings (I)
Symptoms of sciatica (back and leg pain, disability, days of sick leave) were not associated with the degree of disc displacement in MRI, whereas SLR restriction (p<0.01), and nerve root enhancement (p < 0.001) were strongly associated with MRI classification (Figure 4). The results were similar when patients with non-radicular pain radiation into the leg were excluded; only associations with SLR and neural enhancement were weaker. The associations of root level, nerve root enhancement by Gd-DTPA, and degree of neural compromise were also analyzed with the symptoms of sciatica. There were no correlations except that pain upon coughing was more frequent in S1 irritation (p < 0.01). Among the physical measures, SLR restriction correlated with almost all of the symptoms (Spearman coefficients 0.19–0.27). The correlations for lumbar flexion were similar, but weaker. Analyzed by stepwise regression analysis with SLR restriction as the outcome, MRI classification of non-herniations versus herniations explained 20.4% of the variance in SLR restriction. MRI classification did not explain any of the variance in the Oswestry index, or back pain.
Figure 4. Boxplots comparing low-back specific disability measured by Oswestry Index (upper scale) and straight leg raising (SLR, lower scale, shaded boxes) with MRI classification. Note that disability is not associated with the degree of disc displacement, whereas SLR is. The boxplots show the median (50th percentile) and the interquartile (25th to 75th percentile) range. Vertical bars show the minimum and maximum scores. Cont. HNP=contained herniation, noncont HNP=noncontained herniation.