Is hemifacial spasm accompanied by hemodynamic changes detectable by ultrasound?

Arterial tortuosity of the posterior circulation compressing the facial nerve induces the ephaptic axono-axonal cross-talk that sparks hemifacial spasm. We sought if a noninvasive method such as color duplex of these arteries might detect hemodynamical changes in this condition. Nine patients with hemifacial spasm, successfully treated with botulinum toxin, were examined with color-coded duplex ultrasound. Mean blood flow velocities of the vertebral, basilar, posterior inferior cerebellar, and anterior inferior cerebellar arteries were measured and side-to-side comparison performed. In all nine patients, the mean blood flow velocity, averaging across the two arteries, was higher on the side of the hemifacial spasm (Fisher's exact p < 0.008; two-tailed). The results of the repeated measures ANOVA show that the main effect of side of flow was statistically significant, F(1,8) = 17.354, p = .0032, with higher mean blood flow velocities observed on the side of the hemifacial spasm. There was no significant association between the mean flow velocity of the vertebral artery and the side of spasm (p = 0.523). Hemifacial spasm also seems to relate to hemodynamic changes, which may be detectable by color duplex imaging.