Comparison of diagnostic indices of MRI and EMG in diagnosis of lumbar radiculopathy

BACKGROUND: lumbosacral radiculopathy is one of the most common disorders that can be examined by neurologists. Electromyography (EMG) and magnetic resonance imaging (MRI) are used to inspect this disease; however, the application of MRI and EMG in patients with back pain is still under study. This study was designed and implemented to compare the diagnostic values of MRI and EMG in the diagnosis of lumbar radiculopathy. METHODS: This was cross-sectional study which included 62 patients with suspected lumbosacral radiculopathy in a referral neurology clinic in Sanandaj, Iran, in 2009-2010. EMG was considered as the gold standard test. Inclusion criteria were being older than 20 years of age, and suffering from back pain or radicular pain in the lower limbs for more than four weeks. Data were entered into SPSS software and the diagnostic indices and agreement were calculated. RESULTS: The percentage of agreement between MRI and EMG results were calculated as 80.6%. The sensitivity of MRI compared with EMG at different levels was calculated between 44.4% and 79.6% and its specificity was calculated between 46.1% and 94.3%. In total, sensitivity and specificity of MRI were 68.9% and 86.3%, respectively. The Lasègueʹs sign, used for detection of disc herniation, had the sensitivity, specificity, and positive and negative predictive value of 28.8%, 50%, 75%, and 11.9%, respectively. CONCLUSION: MRI and EMG tests have no superiority over one another for the evaluation of lumbar radiculopathy and it is necessary to do both. The Lasègueʹs sign is also not an appropriate test for detection of lumbar spine disc herniation, and it is not helpful in diagnosing or ruling out the disease.