The electrodiagnosis of Guillain-Barré syndrome subtypes: Where do we stand?

It is controversial as to whether the electrophysiological Guillain-Barré syndrome (GBS) subtypes can be diagnosed on the basis of a single study and which criteria sets and cut-offs should be used. Serial electrophysiologic studies have shown that a significant number of patients changed electrodiagnostic subtype largely because of the recognition of reversible conduction failure as a possible evidence of axonal pathology. However, other reports concluded that electrodiagnosis can be made by a single study, the subtypes depending on the characteristic of the criteria set applied. Such divergent views, although explicable by the different methodology employed, can be confusing in the everyday practice. We argue that the pathophysiology of GBS is dynamic and that serial studies allow a more accurate diagnosis of subtypes. A second study, although not always practicable, is recommended in patients showing no clear demyelinating features, low amplitude distal compound muscle action potentials or conduction block without temporal dispersion. For practical purposes, we propose that at a first study Uncini's or Rajabally's criteria sets can be employed for an indicative subtype diagnosis. Finally, although the GBS subtype diagnosis has currently no impact on treatment, we believe that is important for understanding the underlying pathophysiology and prognostication.