Familial hemifacial spasm and determinants of late onset.

The role of hypertension in the late onset of hemifacial spasm (HFS) is evaluated in a family, spanning four generations. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) revealed a variable anatomical relationship between nervous and vascular structures in the symptomatic cerebello-pontine angle. In one case, showing neurovascular conflict (NVC), microvascular surgical decompression was followed by clinical resolution of HFS. Neuroimaging suggesting NVC was found in all symptomatic patients of the last two generations and in three younger subjects not affected by HFS. As a determinant for the late development of clinical expression is reviewed the role of arterial hypertension, detected few years before HFS appearing in all symptomatic subjects. The distribution of NVC in several members of the same family suggests a genetic susceptibility towards vascular anomaly.