The Significance of F-Chronodispersion in the Electrodiagnosis of Guillain-Barre Syndrome and Other Motor Neuropathies

Abstract

To the Editor. —We have studied with interest the report on electrodiagnostic abnormalities in consecutive patients with Guillain-Barré syndrome by Ropper et al¹and agree with the authors that F-wave studies are essential in the neurophysiological evaluation of the syndrome. The purpose of this letter is to emphasize the significance of F-chronodispersion^2,3in patients who may have normal or borderline electrophysiologic results either in all or in some of the tested motor nerves. We would also like to comment that only 10 stimuli used to study F waves as practiced by the authors is insufficient not only for the study of F-chronodispersion but also for the evaluation of other more commonly used F-wave properties (shortest latency, severity of conduction block), particularly in patients with motor neuropathies.² F-chronodispersion has been described by one of us (C.P.P.)³to denote the scatter or dispersion of the relative latencies of