Lumbar MRI– How Useful is It in Surgical Decision Making for Spinal Endoscopy?

The commonly used preoperative lumbar MRI grading lags behind modern patient selection criteria to prognosticate favorable outcomes with the endoscopic decompression for lumbar herniated disc and foraminal and lateral recess stenosis. Since its utilization has evolved into a primary medical necessity criterion for surgical intervention, surgeons often find themselves with clinical symptoms whose treatment is not supported by the MRI report. Therefore, this chapter's authors established the need to determine the MRI's accuracy and positive predictive value for successful postoperative pain relief after endoscopic transforaminal decompression. Using the transforaminal endoscopic technique, the authors performed a critical retrospective analysis of 1839 patients who had surgery for herniated disc and stenosis in the foramina or lateral spinal canal. They calculated the sensitivity, specificity, accuracy, and positive predictive value of preoperative MRI grading, correctly identifying the symptomatic surgical level by correlating it with the directly visualized pathology during surgery and clinical improvements. The lumbar MRI verbal report's sensitivity was calculated at 68.34%, the specificity at 68.29%, the accuracy at 68.24%, and the positive predictive value at 97.38%. The use of surgical MRI criteria for nerve compression detailed within this manuscript improved the calculated sensitivity to 87.2%, specificity to 73.03%, and accuracy to 86.51%. The likely explanation lies in the lack of consensus between radiologists and spine surgeons when grading compression syndromes of the exiting and traversing nerve root. The grading of a preoperative MRI scan for lumbar foraminal and lateral recess stenosis may significantly differ between radiologists and surgeons. The authors conclude that the endoscopic spine surgeon should read and grade the lumbar MRI scan independently.

Keywords: Lumbar endoscopic transforaminal decompression, Preoperative MRI scan.