Fibrillation potentials in paraspinal muscles in chronic lumbosacral radiculopathy

To assess the rate of fibrillation and/or positive sharp waves (FPSW) in the paraspinal muscles (PM) of patients with chronic lumbosacral radiculopathy, PM and leg muscles of 179 patients, 111 men and 68 women, aged 24-68 years (mean 49.0 +/- 9.3), were tested. Illness duration ranged from 8 months to 40 years (9.4 +/- 7.5 years). FPSW were detected in 38 patients (21.2%). In 28 of them (15.6%), FPSW were present in the limb muscles only, in eight (4.5%) in both PM and limb muscles, and in two (1.1%) solely in the PM. FPSW were accompanied in all the above patients by chronic neurogenic changes of motor unit potentials. Logistic regression analysis did not show any significant difference between: (i) the patients with and without fibrillations in leg and/or PM muscles, and (ii) between those with FPSW in both the PM and leg muscles and those with FPSW in the leg muscles only, when the effect of age and duration of illness were considered. These suggest that the paucity of FPSW in the PM is rather genuine and does not depend on the timing of the examination. In consequence, PM electromyography seems to be not as valuable in chronic radiculopathy as it is in the acute stage.