MATERIAL and METHODS: A total of 158 patients (101 males; 57 females) were divided into two main groups depending on existence of the in the vertebral artery (VA). Then, these groups were divided into two sub-groups according to the stenosis severity. All these groups were compared via the following variables: the gender, age, stroke risk factors, and basilar artery deflection angle.

RESULTS: The dominant VA was found more common on the left side; and most of the cases had an adverse directional correlation between the side of the dominant VA and basilar artery bending (p= 0.002). It was noticed that the mean value of the basilar artery deflection angle was higher in the patients with a VA stenosis rate below 70%. In the left VA, hypertension was found higher in the patients with VAS (92.3%, p= 0.012). Furthermore, C-shaped (n=63, 43%) was the most observing morphological change in the basilar artery (BA).

CONCLUSION: Consequently, this study suggests that the VA stenosis below 70% may contribute to the BA tortuosity by affecting asymmetric VA flow. Keywords : Asymmetric flow, Bending side, Deflection angle, Dominant vertebral artery