Acute low back pain and radiculopathy: MR imaging findings and their prognostic role and effect on outcome

Abstract

Purpose: To prospectively determine in patients with acute low back pain (LBP) or radiculopathy, the magnetic resonance (MR) imaging findings, prognostic role of these findings, and effect of diagnostic information on outcome.

Materials and methods: Institutional review board approval and informed consent were obtained. This study was HIPAA compliant. A total of 246 patients with acute-onset LBP or radiculopathy were randomized to either the early information arm of the study, with MR results provided within 48 hours, or the second arm of the study, where both patients and physicians were blinded to MR results, unless this information was critical to patient care. Patients underwent 6 weeks of conservative care. Roland function scoring, visual pain analog, Short Form 36 health status survey, self-efficacy scoring, and a fear avoidance questionnaire were completed at presentation; at 2-, 4-, 6-, and 8-week follow-up; and at 6-, 12-, and 24-month follow-up. A second MR imaging examination was performed at 6-week follow-up. Multivariate logistic regression analysis was used to determine which imaging and nonimaging variables can be used to predict improvement in Roland function and patient satisfaction. The chi(2) test and repeated-measures analysis of variance were used to compare outcome of blinded and unblinded patients.

Results: Herniation was identified in 60% (n = 147) of patients at the initial examination. The prevalence of herniations in patients with LBP (57%) (n = 85) and those with radiculopathy (65%) (n = 62) were similar (P = .217), although patients with radiculopathy were more likely to have stenosis and nerve root compression (P < .006). There was no relationship between herniation type, size, and behavior over time with outcome. An improvement of 50% or more in Roland function score at 6-week follow-up occurred 2.7 times as often among patients with a herniation at baseline (P = .003). Improvement at 6-week follow-up was similar in unblinded (60%) (n = 55) and blinded (67%) (n = 57) patients (P = .397). Self-efficacy, fear avoidance beliefs, and the Short Form 36 subscales were similar for blinded and unblinded patients.

Conclusion: In typical patients with LBP or radiculopathy, MR imaging does not appear to have measurable value in terms of planning conservative care. Patient knowledge of imaging findings does not alter outcome and is associated with a lesser sense of well-being.