Abstract
Aim: Unilateral vertebral artery hypoplasia is considered a risk factor for posterior circulation infarction. Despite the increasing attention on unilateral vertebral artery hypoplasia, few studies have discussed bilateral vertebral artery hypoplasia, its influence on stroke, or its collateral supply from the circle of Willis. We aimed to identify its characteristics, stroke pattern, and unique ultrasonographic and brain imaging findings.Materials and Methods: Of the 1,301 consecutive in-patients diagnosed with acute ischemic stroke from January 2013 to December 2015, medical and laboratory data and stroke or transient ischemic attack history were recorded. We enrolled patients who underwent both brain magnetic resonance imaging and sonography examinations. Vertebral artery and posterior cerebral artery analyses were conducted in accordance with clinical criteria.Results: Adequate imaging data were available for 467 patients. Of these, eight patients met the criteria for bilateral vertebral artery hypoplasia. The mean age was 62.9 ± 12.1 years. There were six male (75.0%) and two female patients (25.0%). A high prevalence of hypertension (7/8, 87.5%) was noted.Sonograms displayed a very low net flow volume in the vertebral arteries, with the average net flow volume being 28.9 ± 9.7 mL/min. A high frequency (6/8; 75.0%) of the fetal variant posterior cerebral artery from the carotids was found. The infarction patterns in these patients were all bilateral, scattered, and in multiple vascular territories.Conclusion: Patients with bilateral vertebral hypoplasia displayed a unique collateral supply, special stroke pattern, and younger stroke onset. Early recognition and stroke prevention should be considered critical in clinical practice.
Highlights
Posterior circulation is comprised of two vertebral arteries that join to form a single basilar artery at the level of the pons
In order to identify obscure clinical features, we reviewed the characteristics of patients with bilateral vertebral artery hypoplasia (VAH) by analyzing their clinical presentations, stroke patterns, risk factors, and the hemodynamics of collateral flow using ultrasonography and brain magnetic resonance imaging (MRI)
Of the 1,301 patients diagnosed with acute ischemic stroke, 467 (149 pateints with posterior circulation infarction) underwent both MRI and sonographic examinations and were enrolled in the present study
Summary
Posterior circulation is comprised of two vertebral arteries that join to form a single basilar artery at the level of the pons. The basilar artery divides into two posterior cerebral arteries at the level of the midbrain [1,2,3]. Case series studies suggest that vertebral artery hypoplasia (VAH) may contribute to posterior ischemic events, especially in patients with other cerebrovascular risk factors [5, 6]. The concept of regional hypoperfusion is associated with unilateral VAH and posterior circulation stroke [7]. The risk of posterior ischemia is related to an increasing degree of VAH [5, 6, 8], regardless of the net flow [7]. An increasing number of studies highlight the importance of unilateral VAH on ischemic stroke [5, 6, 8, 9], literature discussing the influence of bilateral VAH on ischemic stroke is limited [10, 11]
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