Diagnostic Accuracy of the Seated Straight Leg Raise Test for MRI-Confirmed Lumbosacral Radiculopathy: A Prospective Study of 500 Patients

Abstract

Objective:  To determine the diagnostic accuracy of the seated straight leg raise (SLR) test in diagnosing lumbosacral radiculopathy with magnetic resonance imaging (MRI) as the standard of reference. Methods: It was a prospective diagnostic accuracy study at a tertiary neurosurgery clinic. Materials & Methods:  The study enrolled 500 adults with a clinical suspicion of lumbosacral radiculopathy. Each patient was subjected to a standardized seated SLR performed by trained clinicians, and results of lumbar MRI were reported by a consultant radiologist. An index test was taken as positive when the typical pain was reproduced in the radicular area below the knee during knee extension or ankle dorsiflexion. MRI showing nerve-root compression and concordant with the level of the symptom was chosen as the reference standard. Diagnostic accuracy values such as sensitivity, specificity, and predictive values were determined. Results:  In 500 patients, 320 (64.0%) were found to have nerve-root compression on MRI. The seated SLR test had a sensitivity of 78.1% (95% CI 73.3%-82.3%), specificity of 69.4% (95% CI 62.4%-75.7%), positive predictive value of 82.0%, and negative predictive value of 64.1% (95% CI 57.2%-70.5%). The total diagnostic accuracy was 75.0%. No adverse events related to the index test were recorded. Conclusion:  The seated SLR is a practical clinical maneuver with good sensitivity and moderate specificity for MRI-confirmed lumbosacral radiculopathy. It serves as a useful screening tool within a comprehensive clinical assessment, helping to rationalize the use of advanced imaging.