Abstract
BackgroundHemifacial spasm (HFS) is a disabling neurological condition. Vascular tortuosity in HFS patients has not been quantified objectively and its relationship with hypertension and posterior fossa volume (PF) is unknown. In a case control magnetic resonance imaging and angiographic (MRI/A) study, we quantified and compared the vascular tortuosity in HFS and controls, and evaluated its relationship with hypertension and PF.MethodsUsing a commercially available vessel probe tool, an index of tortuosity based on vessel over chord length was employed to quantify vascular tortuosity of the vertebral (VA) and basilar arteries (BA) in 79 subjects (40 HFS, 39 controls).ResultsThe tortuosity index of the BA (1.09 vs 1.16, p = 0.26, 95 % CI 1.07, 1.23), RVA (1.15 vs 1.15, p = 0.83, 95 % CI 1.06, 1.38) and LVA (1.14 vs 1.288, p = 0.16, 95 % CI 1.14, 1.44) was not different between HFS and controls, with adjustments for PF volume and hypertension.ConclusionsContrary to popular belief, our study showed that taking into account hypertension and PF volume, vascular tortuosity of the vertebrobasilar arteries is unlikely to be a major etiologic factor in HFS, though its role in select individuals cannot be excluded. The complex interplay of facial nerve hyperexcitability, genetic predisposition, vascular tortuosity, posterior fossa volume and hypertension needs to be further evaluated.
Highlights
Hemifacial spasm (HFS) is a disabling neurological condition
Imaging All subjects underwent a standardized magnetic resonance imaging and angiographic (MRI) protocol as previously described [3, 4, 10, 14]. This included the 3dimensional constructive interference at steady state (CISS) sequence focused over the posterior fossa and time-of-flight magnetic resonance angiography (MRA) (TR 35, echo time (TE) 7.2, flip angle (FA) 20, number of excitations (NEX) 1, 210 ϫ 512 matrix, 0.8-mm partitions, 96 slices) sequence
The very high intraclass correlation (ICC) values (0.95 to 0.98) for the 3 vessels we examined indicated near perfect agreement between our two raters, supporting the reliability of the measurements based on reproducible and comparable landmarks
Summary
Vascular tortuosity in HFS patients has not been quantified objectively and its relationship with hypertension and posterior fossa volume (PF) is unknown. In a case control magnetic resonance imaging and angiographic (MRI/A) study, we quantified and compared the vascular tortuosity in HFS and controls, and evaluated its relationship with hypertension and PF. The facial REZ from the brainstem is a segment of about 10 mm lying between central and peripheral myelination of axons This reduced myelination predisposes to nerve dysfunction if lesions affect the nerve at this anatomical site. A number of potential predisposing factors to the development of HFS have been investigated, including female sex, increased vascular tortuosity [8], reduced posterior fossa volume [4, 6], and arterial hypertension [3, 4, 11, 12]. To our Edmond et al BMC Neurology (2016) 16:120 knowledge, there have been no published data on quantitative evaluation of vascular tortuosity in HFS
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