Electrophysiological investigations of peripheral and central changes in hemifacial spasm

A short review of the literature and of some personal data that deals with the electrophysiological observations that can be made in patients with hemifacial spasm and that allow one to discuss the two hypotheses that are proposed as possible mechanisms for the pathophysiology of hemifacial spasm is presented. The first part of the paper summarizes the technological and methodological aspects used for investigations. The second part presents data that support the peripheral nerve hypothesis. Although the peripheral nerve hypothesis has been prominent for a long time, recent data in the literature as well as the authors personal findings, as reported in the third section, favour the central or ‘nucleus’ hypothesis, which seems actually the most probable to explain as a whole the clinical and electrophysiological characteristics of HFS.