An Ultrasound Evaluation of the Vertebral Artery in Patients With Vertebral Artery Hypoplasia.

Sina Zarrintan,R Shane Tubbs,Mehrdad Mozafar,Abolhassan Shakeri-Bavil,Mohamad Mozafar,Joe Iwanaga

doi:10.7759/cureus.15020

Abstract

PurposeThe aim of the current study was to assess and compare Doppler ultrasound findings, especially the resistivity index (RI), among and between patients with vertebral artery hypoplasia (VAH) and normal populations.Material and methodsFifteen consecutive patients with VAH (mean age 54 ± 21 years) and 15 sex-matched controls without VAH (mean age 54 ± 22 years) were selected for the study. The vertebral arteries (VA) were examined with Doppler ultrasound. We also explored each group for sex and age differences (young: age ≤ 50, old: age >50).ResultsThe mean RI (MRI), right RI (RRI), left RI (LRI), non-dominant-side RI, and dominant-side RI were significantly higher in the Case Group than the Control Group. In the Case Group, the affected-side RI (A.RI) was significantly higher than the normal side, while the normal side peak systolic velocity was significantly higher than the affected side. The MRI and A.RI were significantly higher in older patients. We also found a significant negative correlation between the mean diameter (MD) and MRI. MRI and A.RI both correlated positively with age in the Case Group, while left peak systolic velocity decreased significantly with age in the Control Group [p-values < 0.05].ConclusionThe dominant VA had a higher RI in the Case Group than the Control Group. It can therefore be inferred that the dominant VA in patients with VAH does not work completely normally, thus making these patients even more susceptible to vertebrobasilar insufficiency and possible strokes.

Highlights

The vertebral artery (VA) is the main artery supplying infratentorial structures such as the cerebellum and medulla; its diameter is determined genetically [1]
The mean resistivity index (RI) (MRI), right RI (RRI), left RI (LRI), non-dominant-side RI, and dominant-side RI were significantly higher in the Case Group than the Control Group
We found a significant negative correlation between the mean diameter (MD) and MRI

Summary

Introduction

The vertebral artery (VA) is the main artery supplying infratentorial structures such as the cerebellum and medulla; its diameter is determined genetically [1]. Variant luminal diameters of the VA range from asymmetry to an even more severe difference, a hypoplastic VA. There seems to be VA asymmetry, defined as a side-to-side diameter difference of 0.3mm, in some 68.9% of the population, the left side VA being dominant [2]. Vertebral artery hypoplasia (VAH) is a relatively common congenital variation. The lack of general consensus concerning the exact cut-off value for a hypoplastic VA diameter, along with the use of different modalities to assess the VA, has led to a wide spectrum of reported VAH prevalences in the literature. The reported frequencies of unilateral VAH range from 2.1% to 26.5%, right side VAH being more frequent [3,4]. Proposed cut-off values for a hypoplastic VA have ranged from 2mm [5] to 3mm [6] in previous studies

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