Basilar artery bending length, vascular risk factors, and pontine infarction

https://doi.org/10.1016/j.jns.2013.12.037Get rights and content

Abstract

Background

Patients exhibiting basilar artery (BA) curvature (not dolichoectasia) are at an increased risk of posterior circulation ischemic stroke. In this study, pontine infarction patients were analyzed to assess the effect of BA bending length (BL) together with other vascular factors on pontine stroke risk.

Methods

Acute pontine infarction patients were divided into BA bending and non-BA bending groups by magnetic resonance angiography (MRA). Patients with BA bending who reported symptoms of dizziness or vertigo but who had not suffered brain infarction constituted the control group. The diameter of the vertebral artery (VA) and BL were measured using MRA. Based on the bilateral VA diameter data in vertebral artery-dominant (VAD) patients, the study participants were divided into three classes for VA diameter: class one, 0.30–0.80 mm (20 cases); class two, 0.81–1.37 mm (20 cases); and class three, 1.38–3.24 mm (20 cases). The measured BL in VAD cases allowed division of patients into three levels for BL: level one, 1.02–2.68 mm (21 cases); level two, 2.69–3.76 mm (20 cases); and level three, 3.77–7.25 mm (19 cases). Vascular risk factors were compared among the three groups. Correlations of BL and VA diameter differences were studied, and multivariate analysis was applied to search for predictors of ischemic stroke in BA bending patients.

Results

Among BA bending, non-BA bending, and control groups, VA dominance (VAD) proved to be a significant differentiator. For all three groups, a patient age of ≥ 65 years, the occurrence of hypertension, smoking, high homocysteine levels, high cholesterol, and a history of type 2 diabetes, were all statistically significant factors (P < 0.05). After adjusting for other relevant factors, multivariate analysis shows that BL of level 3 was an independent risk factor for pontine infarction (OR = 2.74; 95% CI, 1.27 to 4.48). Both BL and diameter differences between the VAs were positively correlated with risk with statistical significance (r = 0.769, P < 0.001).

Conclusions

Both BL and diameter differences between the VAs are positively correlated with the risk of pontine infarction. When BA bending was coupled with other vascular risk factors, the probability of pontine infarction increased. BA bending with a BL greater than 3.77 mm was an independent predictor of pontine infarction.

Introduction

Using the noninvasive cerebrovascular examination methods magnetic resonance angiography (MRA) and computed tomography angiography (CTA), it has been discovered that—by comparison to the standard picture of a straight-line vessel at the anatomical midline—basilar arteries (BAs) exhibit different degrees of bending in cerebrovascular disease patients and healthy subjects [1]. Furthermore, clinical and radiological physicians have, to a large extent, focused on vascular stenosis or occlusion while generally ignoring the presence of vascular curvature during the diagnosis and treatment of cerebrovascular diseases [2]. Because of the importance of the BA in supplying blood to the brain, and given that BA bending among the general populace is common, it has, therefore, been suggested that BA bending should be given more attention in dealing with cases of posterior circulation infarction [3], [4]. However, the underlying reason for BA bending is unclear, and its association with atherosclerosis and ischemic stroke is controversial [5]. Recently, there has been a much greater concern among medical researchers with the occurrence of BA dolichoectasia (BAD), and the suggestion that BAD is related to posterior circulation ischemic stroke [6], [7], [8]; on the other hand, there are, many BA tortuosity cases that are not attributable to BAD. Unfortunately, BA bending, which is linked to ischemic cerebrovascular diseases, has been less well studied [1], [3].

Previous studies on this topic have applied several methods for evaluating BA bending [9], [10]. In this research, BA length (BAL) [1] and bending length (BL) were measured to investigate the relationships between age, gender, and vertebral artery (VA) dominance. BAL and BL were regarded as more convenient, reliable evaluators of BA bending. Based on these findings, it was reasonable to surmise that changes of BAL and BL contribute to posterior circulation infarction, especially of the pons. For the purpose of elucidating the relationship among BL, vascular risk factors, and pontine infarction, the present study was based on high-field-strength MRA to achieve reliably well-defined BA imaging. A cross-sectional, case–control study design was used to reveal the effect of BA bending together with vascular risk factors in patients with pontine infarction.

Section snippets

Patients

From June 2009 to October 2012, 217 acute pontine infarction patients admitted to the Department of Neurology of Zhengzhou People's Hospital (China) were identified; these patients had been diagnosed using magnetic resonance (MR) diffusion-weighted imaging (DWI). On the basis of the Chinese ischemic stroke subclassification (CISS), 97 of these patients were classified as having either small artery disease or infarcts of undetermined etiology [11]; ultimately, 88 of these 97 patients with

General demographic and radiological findings

Of the 46 cases in the BA bending group, occlusion of the paramedian artery occurred in 19 cases, of the short circumflex artery in 12 cases, of the long circumflex artery in 9 cases, and of the two-arterial innervation region in 6 patients. Thirty-two of these 46 patients had infarction located on the side contralateral to BA bending and 14 patients on the side ipsilateral to the bending. A C-type bending was observed in 33 cases and S-type bending in 8 cases. BA bending to the right was seen

Discussion

Our study explored the association among BA bending (not BAD), vascular risk factors and pontine infarction with small artery disease or infarct of undetermined etiology according to the Chinese ischemic stroke subclassification. Infarction was typically located on the contralateral side with respect to the bending in BA-bending pontine infarct patients. According to one vascular remodeling theory, it is presumed that VAs are typically asymmetric with the BA gradually curving in the opposite

Conflict of interest statement

None.

Acknowledgments

The authors wish to thank the Department of Radiology for providing the imaging data. This study was supported by a grant (No. 121PPTGG494-12) from the Bureau of Science and Technology of Zhengzhou City and a grant (201303224) of Medical Science and Technology from the Health Department of Henan Province.

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    Dao-pei Zhang & Shu-ling Zhang contributed equally to the study, and are co-first authors of the article.

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