In a recent study of patients with low back pain, outcomes were no better with early magnetic resonance imaging (MRI) than with plain lumbosacral spine x-rays. But how does MRI compare with no imaging at all?
Researchers at the Cleveland Clinic identified 246 adults (age range, 18–65) who presented with low back pain of less than 3 weeks’ duration; radiculopathy (leg pain greater than back pain; positive straight-leg–raise test) was a dominant feature in 39% of cases. All patients underwent MRI, but they were randomized to an "unblinded" group (MRI results immediately available to clinicians and patients) and a "blinded" group (MRI results withheld). After 6 weeks of conservative treatment, patient satisfaction and degree of improvement on a standardized scale of back pain and function were the same in both groups. During this interval, blinding was removed for only one patient with progressive symptoms who underwent surgery.
Substantial proportions of patients with and without prominent radiculopathy (65% and 57%, respectively) had at least some MRI evidence of degenerative disk disease. However, those with prominent radiculopathy were more likely than those without it to have MRI findings of nerve root compression (46% vs. 27%) and spinal stenosis (30% vs. 17%).
According to this study, early MRI for acute back pain is usually unnecessary. Even in patients with radiculopathy, MRI generally does not change initial clinical management. MRI should be obtained when progressive symptoms or signs suggest that surgery will be necessary, or when the presentation suggests a need to rule out malignancy or infection.
Reference:
Modic MT et al. Acute low back pain and radiculopathy: MR imaging findings and their prognostic role and effect on outcome. Radiology 2005 Nov; 237:597-604.