Electrical impedance myography in the detection of radiculopathy.

Electrical impedance myography (EIM) is a new bioimpedance-based technique for neuromuscular disease assessment. Past work has focused on EIM in the evaluation of diffuse diseases (such as myopathy). In this study, the method's most basic form, linear-EIM, was used for the assessment of restricted radiculopathic disease. Ten normal subjects and 10 patients with unilateral cervical or lumbosacral radiculopathy, diagnosed by electromyography and clinical criteria, were enrolled. Linear-EIM was performed bilaterally on all individuals, and comparisons with the major outcome variable, theta(avg), were made. In normal subjects, side-to-side differences in theta(avg) averaged 0.64% and were no greater than 15.9% in magnitude. In the 10 patients with radiculopathy, theta(avg)was consistently lower in the affected extremity, with a mean side-to-side difference of 15.3%, but ranging as low as 72.3%; there was a tendency for muscles with more prominent chronic neurogenic change to show greater relative reductions in theta(avg). These findings support the potential utility of EIM in assessment of localized neuromuscular disease.