Natural course of disc morphology in patients with sciatica - An MRI study using a standardized qualitative classification system

Study Design. A prospective observational study of patients with sciatica. Objectives. To describe the 14-month development of disc-related MRI findings in patients with sciatica receiving active conservative treatment. Summary of Background Data. Previous studies of disc changes over time have reported reduction of herniations in 35% to 100% of cases. This wide range may be explained by differences in patient populations and classifications used to describe disc herniations. Methods. Data were obtained from patients with radicular pain (n = 181) who were randomly allocated into one of two active conservative treatment regimens lasting 8 weeks. All patients were scanned at baseline and at 14 months of follow-up. Variables of interest in the present study were disc contour and nerve root compromise at the presumed symptomatic disc level. Disc contour was assessed using the recommendations from the Combined Task Forces of NASS, ASSR, and ASNR. Results. In all, 154 patients were included in this study (70 women and 84 men; range, 18-65 years; mean and median age, 45 years). It was possible to identify the symptomatic disc level in 90% of patients. Extrusions or sequestrations were more common in individuals younger than 45 years and in men. Men were also more likely to have nerve root compromise. Only 3% of bulges and 38% of focal protrusions improved, whereas 75% to 100% of broad- based protrusions, extrusions, and sequestrations improved (P < 0.0001). Nerve root compromise improved in 21% to 80% depending on the disc contour. Neither type of treatment nor age had any effect on the development of MRI findings over time. However, nerve root compromise was more likely to improve in men. Conclusions. This classification system could be used to identify the majority of symptomatic disc levels. At 14 months, the MRI outcome was generally good for disc herniations and nerve root compromise. Nerve root compromise had the best MRI prognosis if the disc was extruded at baseline. There were significant differences between men and women in relation to baseline findings as well as in relation to development of MRI findings over time.