Abstract
BACKGROUND CONTEXT Routine use of magnetic resonance imaging (MRI) as a diagnostic tool in lumbar stenosis is becoming more prevalent due to the aging population. However, as the health care expenditure in the United States is rapidly increasing, it is imperative to minimize the use of costly imaging modalities by investigating the utility and cost effectiveness of images routinely obtained. PURPOSE Our study was designed to clarify the utility of routinely repeated MRI in patients with lumbar stenosis, without instability or neurological deficits. STUDY DESIGN/SETTING Retrospective radiographic analysis was performed in the preoperative MRI's of all patients who underwent lumbar decompression via laminectomy, laminotomy, foraminotomy, and/or discectomy, performed at a single tertiary-care institution from 2011 to 2015. PATIENT SAMPLE Among the patients initially identified, those who had at least two preoperative MRI's and were without radiographic instability or clinical neurological deficits were selected. OUTCOME MEASURES For radiographic analysis, grading systems were adopted and modified from Schizas's grading system and Lee’s et al. foraminal stenosis grading system, which were used to measure and compare the initial and the subsequent repeat lumbar MRI's performed preoperatively. If patients were found to have a moderate or severe grade change, and if the surgical plan was altered due to such exacerbated radiographic findings, then their grade changes were considered clinically meaningful. METHODS At each pathologic level, the absolute value of the change in grades for central or lateral recess stenosis, right foraminal stenosis, and left foraminal stenosis in the first preoperative MRI and the repeated MRI was calculated. These change data were used to calculate the mean and median change in each of the three types of stenosis for each pathologic level. Both the mean and median change in stenosis severity were also calculated for the subset of patients that actually had a change in severity. This analysis was undertaken to quantify the extent of change in stenosis severity that could be expected if a patient's stenosis changed at all. Finally, identical calculations were carried out for the subsample of patients who had discectomy as part of the procedure. RESULTS We identified 103 patients who met the inclusion criteria. A total of 17 of those patients had more than one level surgically addressed, and a total of 161 lumbar levels were reviewed. In the subset that had any change, the majority of the grades only had a mild change of one (33 out of 38 patients, 86.8%; 36 out of 41 levels, 87.8%); there was a moderate grade change of two in two levels (4.9%), and a severe change of three in one level (2.4%). There were three levels that had decreased grades (7.3%). All clinically meaningful grade changes were from the subset of patients who had only discectomy or discectomy as part of the procedure. CONCLUSIONS The radiographic evaluation of the utility of routinely repeated MRI's in lumbar stenosis without instability, neurological deficits, or disc herniations demonstrated that there were no significant changes found in the repeated MRI in the preoperative setting. The results of the present study can help to standardize the diagnostic evaluation of lumbar stenosis and to formulate clinical guidelines on the appropriate use of preoperative imaging for lumbar stenosis patients.
Published Version
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