Correlation between Dermatomal Somatosensory Evoked Potential, Needle Electromyography and Magnetic Resonance Imaging in Chronic Sensory Lumbosacral Radiculopathies

Abstract

Objective: To correlate between dermatomal somatosensory evoked potential (DSEP), needle electro myography (EMG) and magnetic resonance imaging (MRI) in patients with clinical picture suggestive of chronic sensory lumbosacral radiculopathy.Design: cross sectional study. Setting: outpatient setting.Participants: 50 patients (29 Males, 21 Females) with chronic sensory lumbosacral radiculopathy. 20 healthy subjects were included as control for DSEP values. Main outcome measures:Medical history, detailed neurological examination, Lumbosacral MRI, lumbosacral DSEP and needle EMG for segment pointing muscles were done for all patients. DSEP were done for lumbosacral roots for control subjects. Results:Mean age of patients 56.36 ± 10.26. Mean disease duration 17.48 ± 6.85 months.Spondylosis constituted 74%, followed by spinal stenosis 14%, lumbar disc prolapse 8%, lastly spondylolithesis 4% In relation to sensory symptoms, DSEP is significantly higher than EMG in detecting lumbosacral radiculopathies (p=0.0001). DSEP sensitivity and accuracy is higher than needle EMG at L4, L5 and S1 In relation to MRI, sensitivity of DSEP at L4 was 93.3%, at L5 and S1 100%. Sensitivity of needle EMG at L4 was 20%, at L5 24.3%, at S1 47.1% . Conclusion: DSEP is highly sensitive than needle EMG in diagnosing and localizing chronic sensory lumbosacral radiculpathies, even if MRI findings are inconclusive.