Diagnostic Characteristics of Neuroradiological Tests in Lumbar Disc Herniation

Background: Many apparent advantages of the magnetic resonance imaging (MRI) in establishing diagnosis of lumbar disc herniation are counter parted by its relatively high cost and sparse availability in developing countries. Thus, a significant portion of patients are still subjected to lumbar disc surgery based solely on computed tomography (CT) findings. Aim: The aim of this study was to compare diagnostic characteristics of afore mentioned radiological tests (CT and MRI) and to investigate if the choice of diagnostic test influences outcome of discectomy. Methods: Basic demographic, clinical and radiological variables were evaluated in a group of 70 patients operated on for disc herniation of whom 30 were operated based on MRI findings and the remainder were operated based on CT scan alone. Outcome was assessed using Visual Analogue Scale (VAS) and Roland-Morris (RM) scale 6 months postoperatively and correlated to the type of neuroradiological examination. Basic diagnostic characteristic of the two diagnostic modalities (MR and CT) were compared. Results: The type of radiological investigation was shown to be statistically poor predictor of outcome after microdiscectomy. Even though MR scan was more sensitive in detecting disc extrusion than CT (sensitivity of 100% versus 65%, respectively), the presence of preoperative MR scan did not influence the outcome. Conclusion: We conclude that although the presence of preoperative MR scan does not influence outcome, higher sensitivity and specificity in detecting disc extrusions and superior ability to detect nerve root compression warrant an introduction of MR scan prior to any disc surgery.