Morphological characteristics of the vertebrobasilar artery system in patients with hemifacial spasm and measurement of bending length for evaluation of tortuosity.

OBJECTIVE: Dominant vertebral artery (DVA), tortuosity, and elongation of the vertebrobasilar artery system are frequently observed in hemifacial spasm (HFS). However, the morphological characteristics of the tortuosity of vertebrobasilar artery system have not yet been elucidated. In this study, we presented a novel method for the measurement of the bending length (BL) of the basilar artery(BA) or vertebral artery (VA) to assess the tortuosity of vertebrobasilar artery system in HFS patients. METHODS: The demographic and morphological characteristics of 135 patients with HFS admitted to the neurosurgical department to undergo microvascular decompression (MVD) were analyzed in this retrospective study. The BL was defined to appraise the tortuous degree of the vertebrobasilar artery system, and according to the BL value, the patients with HFS were divided into two groups: tortuous vertebrobasilar artery (TVA) and non-TVA groups. Additionally, the vessels responsible for HFS were analyzed based on the results of magnetic resonance imaging (MRI) of the two groups. The patients were followed up for 2-6 years post-discharge, and the effect of MVD operation was compared between the two groups. RESULTS: DVA was detected in 60.2% of HFS patients; the incidence of left-sided HFS in the TVA group was significantly higher than that in the non-TVA group (P = 0.013). The proportion of multiple responsible vessels in the TVA group was 68.4% (54/79), while that in the non-TVA group was 4.1% (2/49). The complication rate of the two groups was different, and that of the tortuous group was higher than that of the non-tortuous group. CONCLUSIONS: The morphological characteristics of the vertebrobasilar artery system in patients with HFS were complex. The measurement of BL is an easy and reliable tool to assess the tortuosity of the vertebrobasilar artery system in HFS patients.