Imaging guidelines endorse MRI to guide the placement of epidural steroids for patients with intractable low back pain, and this has become the standard of care, according to an editorial published this week online by the Archives of Internal Medicine. But the benefits of this strategy have never been proven, and now a carefully designed trial has not validated the practice. On the other hand, it may be wise still to follow the guidelines.
The team behind the multicenter trial of MRI before epidural steroid injections, involving participants from Johns Hopkins University Medical Center, the University of Pennsylvania, and Walter Reed Army Medical Center, randomized patients into 2 groups. Everyone got an MRI before the injection, but in only a random half of cases were the physicians who gave the injections allowed to see the images. For the other group of patients, a physician other than the one giving the injection was allowed to see the MRI afterwards and make a post-hoc recommendation.
The physician's ability to see a lumbar MRI before the injection did not have a significant effect on the outcome after 3 months, nor did it have a major effect on decisions about treatment. However, as the editorial points out, the group whose doctors saw the MRI results needed less pain medication after 1 month and also required fewer repeat injections.
Radiological guidelines favor pre-injection MRIs partly to rule out cases in which injections would not be safe, and indeed the group of doctors allowed to see the MRI did rule out a few injections. Also, for a third of patients whose doctors were blinded to the MRI, the physician allowed to see the image would have chosen a different course of action, and that group of patients did have significantly worse outcomes after 3 months.
What's the upshot for doctors in the real world? Although report of the study concludes that MRI "does not improve outcomes" in this setting and has minimal effect on decision making, it would be "premature" to overrule the guidelines, say editorialists Janna Friedly, MD, of the University of Washington and Richard Deyo, MD, PhD, of Oregon Health and Science University. The results do support thinking twice about using epidural injections at all for conditions in which their benefit is especially unclear, they add, such as spinal stenosis and low back pain without radiculopathy.