Symptom duration and spontaneous activity in lumbosacral radiculopathy

A long-held notion in the electrodiagnostic literature is that paraspinal muscles tend to show spontaneous activity (fibrillations and positive sharp waves) on needle electromyography, early on in a lumbosacral radiculopathy, and that more distal muscles become abnormal later in the disease process. The purpose of this study was to determine whether paraspinal muscle and other major proximal and distal muscle spontaneous activity is related to a lumbosacral radiculopathy symptom duration. A multicenter, prospective study that collected standard information on history, physical examination, and electrodiagnostic findings in patients with electrodiagnostically confirmed lumbosacral radiculopathies was undertaken. Multivariate probit analyses of 96 patients identified with a lumbosacral radiculopathy showed no evidence of correlation between spontaneous activity in the paraspinal muscles and symptom duration. Symptom duration was also nonsignificant in nine of the remaining ten lower limb muscles analyzed. These findings emphasize the limitations of using symptom duration when interpreting electrodiagnostic findings in lumbosacral radiculopathy.