Is Repeated Preoperative Magnetic Resonance Imaging Necessary Before Planned Decompressive Surgery for Lumbar Spinal Stenosis?

Background: Currently, there are different routines in Norwegian hospitals regarding how recent magnetic resonance imaging (MRI) of the lumbar spine should be performed before surgery. Patients with lumbar spinal stenosis from the Norwegian degenerative spondylolisthesis and spinal stenosis study, who had 2 preoperative MRIs performed within the year before surgery, were included. The aim of the present study was to evaluate the utility of repeated preoperative MRI for patients undergoing decompressive spine surgery for degenerative spinal stenosis. Methods: For all included patients, the changes between the 2 preoperative MRIs were investigated for disc degeneration (Pfirrmann's classification), foraminal stenosis (Lee's classification), spondylolisthesis, and central canal stenosis (Schizas score and dural sac cross-sectional area). Results: A total of 65 patients (78 levels) were included. Thirty- seven patients were women, and the mean age was 67 (range 48-79) years. Schizas score showed a clinically meaningful change of & PLUSMN;2 or 3 grades in 5 levels, and dural sac cross-sectional area was reduced in 47 levels with a mean change of -2.3 mm2. Three levels had a clinically relevant change in grade of foraminal stenosis of & PLUSMN;2. For disc degeneration, 53 of the levels had no change, and the rest of the levels had a change of & PLUSMN;1 grade. Increased spondylolisthesis was measured at 21 levels, and the mean slip was <2 mm. Also, 4 levels had >2 mm slip. Conclusion: For patients undergoing surgery for lumbar spinal stenosis, repeated MRI within the year before planned surgery showed few significant changes in common radiological parameters. The benefit for the surgeon of repeat MRI is therefore limited. Level of Evidence: 2.