In patients with ankylosing spinal disorders who have sustained acute spine fractures, magnetic resonance imaging (MRI) should not be obtained routinely, but it may play an important diagnostic role in patients with non-ankylosed levels in which a discoligamentous injury may have occurred and in those with neurologic deficits that require exploration of the spinal canal to assess causes of neurologic injury, according to data from a retrospective cohort study published in The Spine Journal.

The use of MRI has been proposed as a routine method to help identify noncontiguous fractures among patients with ankylosing spinal disorders who have unexplained neck or back pain or known injuries. Therefore, investigators sought to evaluate the frequency with which an MRI identified an injury that was not previously detected using computed tomography (CT). As a secondary outcome, they attempted to identify clinical or CT findings that might render use of an MRI particularly helpful. The researchers also took into consideration that some studies have demonstrated a relationship between neurologic injury and the patient transfer/positioning required with an MRI.

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A total of 124 patients with either idiopathic skeletal hyperostosis or ankylosing spondylitis were identified by searching the radiology database of a level I trauma center. Final radiology reports were evaluated to establish the presence and type of fracture based on CT scans. MRIs were then reviewed to evaluate whether additional fractures or injuries had been identified beyond those already detected from the CT scan. Mode of injury, neurologic status at hospital admission and discharge, type of fracture, and final intervention were determined based on operative reports or inpatient notes.

The results of the study revealed that in 4.8% of patients, additional injuries were revealed on MRI that had not been detected with CT scans. Of these 6 patients, 4 had a change in their treatment plan (3 surgical and 1 nonsurgical) that was based on the findings of subsequent MRIs. The other 2 patients had additional injuries identified on MRI but had no change in their treatment plan.


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The investigators concluded that based on the results of this comparison of MRI vs CT, only 1 fracture was missed on CT imaging, with the other missed injuries all being either discoligamentous hyperextension injuries through mobile disks or intracanal pathology. They caution against the overuse of MRI in certain patients with ankylosing spinal disorders, but do recognize the utility of this technique in certain individuals to avoid the possible risk for neurologic compromise associated with delayed or missed diagnoses.

Reference

Tavolaro C, Ghaffar S, Zhou H, Nguyen Q, Bellabarba C, Bransford R. Is routine MRI of the spine necessary in trauma patients with ankylosing spinal disorders or is a CT scan sufficient? [published online March 16, 2019]. Spine J. doi:10.1016/j.spinee.2019.03.004