Assessment of lumbar radicular pain. Validity and predictive value of clinical tests

Abstract: Radicular pain is in the majority of cases caused by a disc herniation with a coexisting inflammation. It is characterized by positive neural tension tests, such as the Slump test, and by decreased range of motion (ROM) in the straight leg raising test (SLR) and lumbar flexion (Fingertip-to-floor test[FTF]). This may suggest that improvement in ROM correlates to reduction of self-reported disability in patients with radicular pain as determined by the Slump test. It may also suggest that a locally administered anti-inflammatory treatment, such as transforaminal epidural steroid injection (TESI), provides greater leg pain reduction in subjects with positive Slump test compared to those with a negative test. The aims of this thesis were, in a sample with acute/sub-acute low back pain (Cohort A), to distinguish a subgroup with radicular pain as determined by a positive Slump test and to evaluate the validity and predictive value of FTF and SLR for subjects with and without radicular pain, and in a sample with chronic low back related leg pain (Cohort B) to evaluate the predictive value of the Slump test in determining the response to TESI. In addition, other methods to determine radicular pain, i.e. neurologic examination and magnetic resonance imaging (MRI), were used as comparison. Reference standards and primary outcomes were reduction of self-reported disability and leg pain after 3-4 weeks and one year. Validity and predictive value were evaluated using correlation (r) and regression analysis, respectively. For the group with positive Slump test in Cohort A, good validity of FTF was found as 4-week improvement in FTF correlated well to 4-week reduction of disability (r=0.66). A fair respective correlation was found between disability and SLR (r=0.28). The 4-week improvement in FTF predicted one-year reduction of disability. In Cohort B and at a time point when the greatest effect was expected (at 3-week follow-up), the greatest reduction of leg pain after TESI was found for subjects with positive Slump test. The negative Slump test group had no or minor 3-week effect of TESI. However, the Slump test failed to predict the one-year response to TESI, in contrast to MRI-verified nerve root compression. Neurologic examination results failed to predict 3-week and one-year response to TESI. In conclusion, for the group with acute/sub-acute radicular pain as determined by the Slump test, in contrast to SLR, we found good validity and predictive value for FTF. The Slump test was the best predictor of 3-week response to TESI and is, thus, suggested as a valid method to determine radicular pain in subjects with chronic low back related leg pain