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).

BackgroundIt is not clear whether the configuration of the posterior part of the circle of Willis (CW) depends on the proximal part of the vertebrobasilar system. Our aim is to evaluate the posterior part of CW in association with different size of vertebral arteries (VA) in healthy volunteers.Materials and methodsThe present study was based on a sample of 923 healthy volunteers who were examined from 2013 through 2018. The duplex ultrasonographic examination of the extracranial vertebral (VA) and carotid arteries was performed. VA was defined as hypoplastic (VAH) when VA diameter in the entire course was less than 2.5 mm. All the participants underwent magnetic resonance angiography (MRA) examination. All the component vessels of the circle of Willis were assessed in each individual. We classified the posterior communicating artery (PCoA) as presence PCoA, absence/hypoplastic PCoA and fetal-type posterior circle of Willis (FCW) in which the major stem of the posterior cerebral artery (PCA) arises from ipsilateral internal carotid artery (ICA). The comparison of the posterior part of CW was made in subjects with normal VA and VAH of a different degree (communicating with basilar artery (VAH-BA) and not communicating with the basilar artery (VAH-PICA)).ResultsFCW was found in 15.9% of subjects, bilaterally–in 2.3%. FCW was more frequent in individuals with VAH than in those with normal VA (accordingly, 28.8% vs. 13.5%, p<0.001. Moreover FCW was recorded in 50% of the subjects with VA—PICA in comparison with 13.5% of those with normal VA and 22.8% with VAH—BA, p<0.005. On the contrary, absence/hypoplasia of both PCoA was mostly found in the group with normal VA in comparison with VAH-BA and VAH-PICA (accordingly, 50.7%, 38.6% and 12.5%, p<0.01).ConclusionIndividuals with VAH have a different pattern of the posterior part of CW in comparison with those with normal VA. With the increasing degree of VAH, the proportion of FCW increases, while the proportion of absence/hypoplastic of both PCoA decreases.

SANTRAUKAReikšminiai žodžiai: slankstelinės arterijos hipoplazija, paplitimas, demografiniai rodikliai, antropometriniai rodikliai, pratekančio kraujo tūris. Tikslas. Įvertinti slankstelinių arterijų hipoplazijos paplitimą tarp jaunų žmonių, slankstelinių arterijų hipoplazijos spindžio priklausomybę nuo lyties, antropometrinių rodiklių bei nustatyti ryšį tarp pratekančio kraujo tūrio ir slankstelinių arterijų hipoplazijos laipsnio. Medžiaga ir metodai. Tirta 180 sveikų savanorių studentų, 45 vyrai ir 135 moterys, jų amžiaus vidurkis 24,7 ± 0,7 metų. Tiriamiesiems Aloka Prosound α10 ultragarsiniu aparatu buvo atliktas ultragarsinis miego ir slankstelinių arterijų ekstrakranijinės dalies tyrimas, naudotas 7,5 MHz tiesinis daviklis. Visiems tiriamiesiems matuotas abiejų slankstelinių arterijų spindis V2 segmente, šiose arterijose registruotas pratekančio kraujo tūris. Rezultatai. Slankstelinių arterijų hipoplazijos, kurių spindis <3 mm, diagnozuota 27,8 proc. žmonių. Tačiau slankstelinių arterijų spindis <2,2 mm buvo tik 1,1 proc. tiriamųjų, spindis <2,5 mm -tik 5 proc. tiriamųjų. Dešinės pusės slankstelinių arterijų hipoplazija buvo beveik dvigubai dažnesnė negu kairės (atitinkamai 17,2 proc. ir 8,9 proc.). Slankstelinių arterijų hipoplazijos dažnesnės moterims (31,8 proc.) nei vyrams (17,8 proc.), p = 0,042. Aukštesnių žmonių kraujagyslės buvo platesnės. Gauta silpna, bet statistiškai reikšminga koreliacija: tarp dominantinės slankstelinės arterijos spindžio ir ūgio (r = 0,25; p = 0,004), tarp suminio abiejų slankstelinių arterijų spindžio ir ūgio (r = 0,22; p = 0,004), tarp kairės slankstelinės arterijos spindžio ir ūgio (r = 0,25; p = 0,004). Tarp nedominantinės slankstelinės arterijos spindžio ir ūgio bei dešinės slankstelinės arterijos spindžio ir ūgio statistiškai reikšmingos koreliacijos negauta. Pratekančio kraujo tūris per slankstelinę arteriją koreliuoja su jos spindžiu (r = 0,5; p < 0,001). Bendras pratekančio kraujo tūris per abi arterijas patikimai dažniau sumažėja (<100 ml/min), kai slankstelinės arterijos spindis <2,5 mm (atitinkamai 53,9 proc. tiriamųjų, kuriems slankstelinių arterijų spindis <2,5 mm, ir tik 23,5 proc. tiriamųjų, kurių arterijų spindis >2,5 mm; p = 0,026). Išvada. Slankstelinių arterijų hipoplazija yra dažna anomalija, bet didelio laipsnio hipoplazija, turinti įtakos pratekančio kraujo tūriui, tarp jaunų žmonių sutinkama retai. Slankstelinių arterijų spindžio pasiskirstymas populiacijoje priklauso nuo jos demografinių ir antropometrinių rodiklių. ABSTRACTKey words: vertebral artery hypoplasia, prevalence, demographic indicators, anthropometric indicators. Aim. To evaluate the prevalence of vertebral artery (VA) hypoplasia in young adults and to find association between the VA diameter and blood flow volume and association between the VA diameter and demographic as well as anthropometric indicators. Matherial and methods. 180 healthy young adults were examined: 45 men and 145 women aged 24.7 ± 0.7 years. Ultrasound examination of extracranial part of vertebral (VA) and carotid arter...

Background and Objectives: Vertebral artery hypoplasia (VAH) is a controversial risk factor for cerebral infarction. The aim of this study was to analyze the prevalence of vertebral artery hypoplasia and to evaluate its association with vertebrobasilar cerebrovascular accidents. Materials and Methods: The study was conducted in the Neurology Departments of the Republican Vilnius University Hospital from 2015 to 2020. Data of 742 subjects (133 patients with posterior circulation infarction or vertebral artery syndrome (PCI/VAS), 80 patients with anterior circulation infarction (ACI) and 529 control subjects with no symptoms of cerebrovascular accident) were analyzed. Ultrasound examination of the extracranial internal carotid and vertebral arteries (VA) was performed, risk factors were recorded. Results: The mean age of the subjects was 64.51 ± 13.02 years. In subjects with PCI/VAS the diameter of VA was smaller, and the prevalence of VAH was higher compared to those in subjects with ACI and in the control group. A higher degree of VAH in subjects younger than 65 years of age increased the risk of PCI/VAS. Subjects with non-dominant VA diameter of 2.7–2.9 mm had 2.21 times higher risk of PCI/VAS, subjects with non-dominant VA diameter of 2.5–2.6 mm had 2.36 times higher risk of PCI/VAS, and subjects with non-dominant VA diameter of 2.2–2.4 mm had 4.12 times higher risk of PCI/VAS compared with subjects with non-dominant VA diameter of ≥3 mm. Among patients with PCI/VAS those with VAH had lower rates of ischemic heart disease compared with patients with normal VA diameter. There was no difference in the rates of other risk factors between PCI/VAS patients with and without VAH. Conclusions: Vertebral artery hypoplasia is not a rare finding in individuals without symptoms of cerebrovascular accident, but more frequent in patients with vertebrobasilar cerebral infarction or vertebrobasilar artery syndrome. Vertebral artery hypoplasia can be considered a risk factor for posterior circulation infarction in subjects under 65 years of age.

2 2 21Background. It is not clear whether the configuration of the posterior part of the circle of 22 Willis (CW) depends on the proximal part of the vertebrobasilar system. Our aim is to 23 evaluate the posterior part of CW in association with different size of vertebral arteries (VA) 24 in subjects free from stroke and TIA. 25 Materials and methods. The present study was based on a sample of 923 subjects free from 26 stroke and TIA who were examined from 2013 through 2018. All the participants underwent 27 MRA examination. The duplex ultrasonographic examination of the extracranial arteries 28 (vertebral and carotid) was performed. VA was defined as hypoplastic (VAH) when VA 29 diameter in the entire course was less than 2.5 mm. We classified the posterior 30 communicating arteries (PCoA) as presence PCoA, absence/hypoplastic PCoA and fetal CW 31 (FCW). The comparison of the posterior part of CW was made in subjects with normal VA 32 and VAH of a different degree (communicating with basilar artery (VAH-BA) and not 33 communicating with the basilar artery and terminating in PICA, neck or aplasia (VAH-34 PICA)).35Results. FCW was found in 15.9% of subjects, bilaterally -in 2.3 %. The coexisting VAH 36 was more common in subjects with FCW rather than in those with adult CW (respectively, 37 28.6% and 13.4%, p<0.001). Aplasia of A1 of the anterior cerebral artery, i.e. blood flow 38 redistribution in the anterior part of anterior circulation in the majority of cases (in 6 of 7 39 cases) was found ipsilaterally to FCW. FCW was recorded in 50% of the subjects with VA -40 PICA in comparison with 13.5% of those with normal VA and 22.8% with VAH -BA, 41 p<0.005. On the contrary, absence/hypoplasia of both PCoA was mostly found in the group 42 with normal VA in comparison with VAH-BA and VAH-PICA (accordingly, 50.7%, 38.6% 43 and 12.5%, p<0.01). 3 3 44 Conclusion. Individuals with VAH have a different pattern of the posterior part of CW in 45 comparison with those with normal VA. With the increasing degree of VAH, the proportion 46 of FCW increases, while the proportion of absence/hypoplastic of both PCoA decreases. 47 Key words. Circle of Willis . Fetal variant. Hypoplasia. Vertebrobasilar system. Vertebral 48 artery. 49 50 6 6 116 3. We defined the circle of Willis as fetal if PCA arises from the internal carotid artery, 117 independent on the presence or absence of the atretic P1 segment. All other 118 individuals were named as having" adult" configuration of CW. The subjects with 119 adult and rarely found transitional CW configuration were included in this group. In 120 cases of adult configuration, P1 segment of PCA had a diameter larger than PCoA 121 while in transitional configuration, P1 segment and PCoA have close diameters.122 4. The posterior part of CW was documented as presence of PCoA, absence/hypoplastic 123 PCoA and FCW. The subjects with hypoplastic PCoA were included in the same 124 group as those with absence of PComA since both groups have minimal or no 125 possibilities to compensate the reduc...