Ischemic stroke patterns and hemodynamic features in patients with small vertebrobasilar artery

https://doi.org/10.1016/j.jns.2009.07.007Get rights and content

Abstract

Background

To determine the role of small vertebrobasilar artery (SVBA) in patients with posterior circulation stroke (PCS), we evaluated the ischemic patterns, collateral features, and stroke mechanisms in PCS patients with SVBA.

Methods

Ischemic findings on magnetic resonance (MR) imaging were correlated with 3D time-of-flight/contrast-enhanced MR angiography and/or catheter angiography in 18 patients (mean age, 68.0 ± 11.8 years; 9 males). SVBA (lumen diameter of < 3 mm) was compared with stenotic normal-sized VBA (NVBA) in 14 PCS patients.

Results

Ischemic lesions were predominantly observed in the cerebellum and/or medulla (vertebral artery (VA) territory). All subjects had fetal posterior circulation (FPC) from the internal carotid artery to the posterior cerebral artery. Sixteen patients (88.9%) had distal or diffuse VA stenosis/occlusion. In 14 patients (77.8%), long circumferential artery (LCA) was prominently observed. In atherothrombotic patients, infratentorial PCS might occur following artery-to-artery embolism from the low-flowed or stenotic VA to LCA. Ischemic patterns between subjects with and without VA disease were almost similar. As the degree of VA disease increased, the frequency of LCA prominence showed an increased tendency (P = 0.003). Relatively small, scattered infarcts were observed in patients with SVBA than in those with stenotic NVBA.

Conclusions

FPC does not protect against infratentorial PCS. Regardless of extensive arterial lesions, relatively small infarcts may be due to previously established collaterals from the LCA, which could compensate for the defects in the infratentorial area.

Introduction

A small vertebrobasilar artery (SVBA) is infrequently observed in stroke patients, regardless of whether it is directly related to ischemic stroke. It may not be possible to adequately visualize an SVBA on three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography (MRA); moreover, because its exact nature is unclear, it attracts little attention until posterior circulation stroke (PCS) occurs. Ischemic patterns in patients with SVBA appear to be different from those in subjects with a normal-sized VBA (NVBA). Although it has been reported that SVBA might induce PCS [1], the collaterals that would compensate for the posterior circulation system in the case of ischemic stroke have not been well established. Furthermore, a correlation of neuroimaging findings with vascular pathologies has not been attempted in PCS patients with SVBA. Therefore, we evaluated the ischemic pattern of the vascular lesions by magnetic resonance (MR) imaging and the hemodynamic pattern (collateral circulation) by MR angiography (MRA) and/or transfemoral cerebral angiography (TFCA) and assessed the stroke mechanism in PCS patients with SVBA by using the abovementioned techniques together with transcranial Doppler (TCD).

Section snippets

Patient selection

The present study is a case series from 2 academic centers (Seoul National University Hospital (SNUH) and Myongji Hospital (MJH)). We assessed 1959 acute ischemic stroke patients (SNUH: n = 1604, between September 2003 and February 2006; MJH: n = 355, between March 2006 and September 2007). Within 1 week of symptom onset, patients underwent brain MRI and 3D TOF MRA by a 1.5-Tesla MR system (SNUH: Siemens 1.5 Vision, Erlangen, Germany; MJH: Intera 1.5 T 10.3 version, Eindhoven, Netherlands). The

Demographic features, risk factors, and stroke subtypes of the study subjects

In this study, 9 men and 9 women were included. None of the study patients had experienced a VBA dissection or stenosis (> 50%) or occlusion of the internal carotid artery. Table 1 lists the baseline characteristics and angiographic findings of the study patients with SVBA. The mean age of the patients was 68.0 ± 11.8 years (range, 46–87 years). Most of the patients had vascular risk factors: hypertension in 15 patients (83.3%), diabetes in 4 patients (22.2%), Af in 3 patients (16.7%), and smoking

Discussion

To date, few studies have focused on SVBA, except to assess to what extent SVBA might result in PCS [1]. Our study focused on the MR ischemic patterns, hemodynamic features (collateral circulation), and possible stroke mechanisms in PCS patients who showed small or faintly visible VBA on MRA.

FPC is a fetal variant of the posterior cerebral artery (PCA) from the internal carotid artery. The prevalence of FPC is reported to be 32% in the general population [13]. The present study showed the

References (22)

  • M. Schöning et al.

    The development of hemodynamics in the extracranial carotid and vertebral arteries

    Ultrasound Med Biol

    (1998)
  • S. Chaturvedi et al.

    Ischemia in the territory of a hypoplastic vertebrobasilar system

    Neurology

    (1999)
  • W.R. Smoker et al.

    High-resolution computed tomography of the basilar artery: normal size and position

    AJNR Am J Neuroradiol

    (1986)
  • C.M. Fisher et al.

    Atherosclerosis of the carotid and vertebral arteries—extracranial and intracranial

    J Neuropathol Exp Neurol

    (1965)
  • P.J. Touboul et al.

    Duplex scanning of normal vertebral arteries

    Stroke

    (1986)
  • C. Argenson et al.

    The vertebral arteries (segments V1 and V2)

    Anat Clin

    (1980)
  • J.P. Francke et al.

    The vertebral arteries (arteria vertebralis). The V3 atlanto-axial and V4 intracranial segments-collaterals

    Anat Clin

    (1981)
  • L. Tatu et al.

    Arterial territories of human brain; brainstem and cerebellum

    Neurology

    (1996)
  • A. Auer et al.

    Magnetic resonance angiographic and clinical features of extracranial vertebral artery dissection

    J Neurol Neurosurg Psychiatry

    (1998)
  • J. van der Grond et al.

    A fetal circle of Willis is associated with a decreased deep white matter lesion load

    Neurology

    (2004)
  • A.V. Alexandrov

    Transcranial Doppler sonography: principles, examination technique, normal values, and waveform patterns

    Vasc Ultrasound Today

    (1998)
  • Cited by (13)

    • Mechanisms of Stroke in Patients with Fetal Posterior Cerebral Artery

      2022, Journal of Stroke and Cerebrovascular Diseases
      Citation Excerpt :

      Some post-mortem studies have described that FTPs are associated with an increased stroke risk,3,4 which, however, was not confirmed in another clinical study.5 There also were discordant results regarding the relationship between FTP and the etiology of stroke.6,7 Generally, little research has been done on the infarct pattern, lesion location and stroke mechanisms of PCA ischemic stroke associated with FTP.

    • Relationship between Vertebral Artery Hypoplasia and Posterior Circulation Ischemia

      2016, Journal of Stroke and Cerebrovascular Diseases
      Citation Excerpt :

      Therefore, if the supplemental system fails, the compensatory mechanisms are exhausted and ischemic stroke can occur.11 Third, a hypoplastic VA could presumably be more susceptible to prothrombotic or atherosclerotic processes (due to decreased flow volume and flow velocities) than normal VAs.14 In our study, large-artery atherosclerosis was an independent factor for VA occlusion.

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

      2014, Journal of the Neurological Sciences
      Citation Excerpt :

      In our patient population, a majority of infarct events occurred in the area supplied by the paramedian artery, and clinical symptoms were relatively minor according to the NIHSS score. Previous studies have likewise suggested that clinical symptoms of brain infarction in patients with brain artery abnormalities were also relatively minor [17,18], agreeing with our observation that the clinical symptoms in our BA-bending pontine infarction patients (not BAD) were relatively minor. Our findings indicate that advanced age (> 65), a history of hypertension, cigarette smoking, a high homocysteine level, a history of high cholesterol, and type 2 diabetes mellitus probably contributed to the risk of pontine infarction in BA bending patients.

    View all citing articles on Scopus
    View full text