Electrophysiological determination of the site involved in generating abnormal muscle responses in hemifacial spasm
✍ Scribed by Frédéric Tankéré; Thierry Maisonobe; Georges Lamas; Jacques Soudant; Pierre Bouche; Emmanuel Fournier; Jean Claude Willer
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 146 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0148-639X
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✦ Synopsis
In patients with hemifacial spasm (HFS), abnormal muscle responses due to abnormal cross-transmission are observed in facial muscles. However, the site in the facial nerve responsible for the crosstransmission remains a matter of controversy. We have developed a model in which by considering the electrophysiological parameters involved in producing the abnormal muscle response, we can determine the site of the abnormal cross-transmission within the facial nerve. This model was applied to HFS patients with three different etiologies: idiopathic, post-Bell's palsy, and post-XII-VII anastomosis. Our data show that: in idiopathic HFS, the cross-transmission may occur in the facial nerve at the level of the pontocerebellar angle; in post-Bell's palsy, it is inside the petrous bone; and in XII-VII anastomosis, it must be in the extracranial part of the facial nerve. The possible mechanisms for this cross talk are discussed in terms of ephaptic transmission or of a central hyperexcitability in the facial motor nucleus.