Association between vertebral artery hypoplasia and posterior circulation stroke

Abstract

BackgroundThe clinical significance of vertebral artery (VA) hypoplasia is under discussion. The aim of this retrospective study is to evaluate a hypothesis of a possible causal link between VA hypoplasia (VAH) and the incidence of posterior circulation stroke (PCS) or TIA depending on the degree of VAH and vascular risk factors.MethodsA total of 367 symptomatic (PCS or TIA) and 742 asymptomatic subjects, were selected to participate in the study. The extracranial arteries were examined by ultrasound. VAH was defined as VA diameter in entire course <3 mm, although different degrees of VAH were examined. All the symptomatic patients underwent MRI or CT and MRA or CTA. The study assessed all the subjects in terms of their age, gender, co-risk factors (hypertension, hyperlipidemia, diabetes mellitus, peripheral arterial diseases, atrial fibrillation, myocardial infarction), as well as height of 180 healthy volunteers.ResultsVAH, regardless of the degree of severity, was more frequent in patients with non-cardioembolic PCS or TIA rather than in asymptomatic patients. The increasing degree of hypoplasia in patients under 65 years of age was a predictor of PCS/TIA, OR = 1.8, 95 % CI: 1.3-2.5; p < 0.001. In subjects older than 65 years of age, this association failed. Only in patients aged under 50, VAH was significantly more frequent in the TIA group rather than in the PCS group (68.2 % and 50 %, respectively; p = 0.047). The optimal VA diameter cutoff point separating PCS/TIA and asymptomatic group was 2.7 mm. This value may vary in different populations, because VA diameter showed a significant dependence on sex as well as anthropometric parameters (height). With the increasing degree of VAH, the likelihood of the occurrence of the distal VA part stenosis/occlusion was growing (OR = 1.6, 95 % CI: 1.2-2.1; p = 0.002). The distal VA stenosis/occlusion was likely to occur where the VA diameter was <2.2 mm.ConclusionsThe impact of the VAH on PCS/TIA and its pathogenetic mechanism was significantly influenced by age. The cutoff point of VA diameter, affecting the occurrence of PCS in different populations may vary because VA diameter depends on gender and anthropometric parameters (especially height).

Extracranial and Intracranial Ultrasonographic Findings in Posterior Circulation Infarction

“…A significantly higher frequency of vertebral artery hypoplasia in the posterior circulation infarction group (44.75%; Table ) and a high correlation with vertebral artery territory ischemic stroke (55.56%) were noted. These results were consistent with previous clinical studies and further highlight the importance of vertebral artery hypoplasia in posterior circulation infarction …”

“…Traditionally, basilar artery or distal vertebral artery stenosis is considered an important risk factor for brain stem stroke. 1,3,[6][7][8] In recent years, series of studies pointed out a possible correlation between vertebral artery hypoplasia [9][10][11][12][13] and posterior circulation infarction. Cohort studies also supported clinical observations that a hypoplastic vertebral artery aggravates the vascular risk for posterior circulation infarction synergistically.…”

Ultrasound Findings Disclose the Mutual Impact of Vertebrobasilar Dolichoectasia and Vertebral Artery Hypoplasia

“…From the viewpoint of hemodynamics, statistically significant differences in the side‐to‐side extracranial vertebral flow volume indicate the possibility of chronic hypoperfusion over the vertebrobasilar system. Several studies reported the importance of VAH‐related inadequate net VA flow or low velocity, eventually in a higher incidence of stroke events, particularly in the ipsilateral posterior circulations . A compensatory mechanism by which the contralateral VA becomes dominant to achieve the adequate blood flow for brain circulation has also been reported .…”

“…Clinically, both conditions contribute to the extent of ischemic strokes and especially posterior circulation strokes in the vertebrobasilar arterial territory . In addition, among patients with unilateral VAH, a trend of both arterial dilatation over the other dominant VA and elongation to the BA has been observed .…”

Controlling Water Exchange Kinetics and Improving ParaCEST Imaging

“…Radio-ligands are preferred because they can transform normally nonspecific radioisotopes into targeted agents to specifically bind to certain types of tissue which causes the radioisotope to accumulate in desired areas of the body, thereby increasing the amount of signal seen in the image in that area. FDA-approved radioisotopes include the following: 11 C, 14 C, 13 N, 15 O, 18 F, 67 Ga, 82 Rb, 89 Zr, 89 Sr, 90 Y, 99 Mo, 99 Tc, 111 In, 123 I, 125 I, 131 I, 133 Xe, 153 Sm, 201 Tl, and 223 Ra. Both labelled radiotracers and radioisotopes are injected into a patient and the natural decay process of the isotopes occurs inside the body while detectors monitor the radiation given off from the decay process in order to create images.…”