Implications of cranial arterial stenosis and dolichoectasia for cerebral small vessel disease etiopathogenesis: findings from a prospective mild stroke cohort

BackgroundStenosis and dolichoectasia of cranial arteries likely reflect distinct mechanisms. Their contributions to lacunar stroke and cerebral small vessel disease (cSVD) remain contentious. We investigated associations of large artery stenosis (LAS) and arterial widening with stroke subtype, cSVD markers, incident infarcts, and clinical outcomes. MethodsWe prospectively recruited patients with lacunar or mild non-lacunar stroke, with demographic, stroke-related, cognitive, functional, and MRI (index and incident infarcts, cSVD markers) assessments at baseline and one year. LAS was defined as [≥]50% intracranial or cervical artery stenosis; basilar artery dolichoectasia (BADE) by basilar artery diameter, bifurcation height, and lateral displacement; and intracranial carotid and middle cerebral artery diameters were also measured. Associations were estimated using multivariable regression adjusted for age, sex, and vascular risk factors. We further conducted a systematic literature review to synthesize evidence on relationships between large artery pathology and cSVD. ResultsAmong 229 patients (mean age 65.9{+/-}11.1 years; 131 [57.2%] lacunar stroke), LAS and BADE were present in 20.5% and 15.7%, respectively. After adjustment, LAS (odds ratio [OR], 0.49; 95%CI, 0.23-0.99) and the presence of any embolic source were associated with lower odds of lacunar versus non-lacunar stroke, and not with cSVD markers or incident infarcts. In contrast, BADE was strongly associated with lacunar stroke (OR, 4.67; 95%CI, 1.87-13.14), higher cSVD scores (ordinal analysis; OR, 2.57; 95%CI, 1.28-5.25), incident infarcts (75% subcortical; OR, 2.29; 95%CI, 1.01-5.14), and greater progression of white matter hyperintensities over one year ({beta}, 0.15; 95%CI, 0.01-0.29; per log10-transformed volume). Similar associations were observed for wider intracranial arteries. The systematic review supported these findings. ConclusionscSVD, including lacunar stroke, was unrelated to LAS, but strongly associated with dolichoectasia and wider arteries. These findings support a non-atheromatous, intrinsic microvascular pathology, particularly segmental arteriolar disorganization, as the principal mechanism of lacunar stroke and cSVD. Mechanism-specific diagnostic and therapeutic strategies are warranted. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABS[bullet] Large artery stenosis was unlikely to represent a causal mechanism for lacunar stroke and showed no association with cerebral small vessel disease (cSVD) imaging markers. [bullet]Dolichoectasia and intracranial arterial widening emerged as vascular phenotypes strongly associated with cSVD, including its progression and lacunar stroke subtype. What Are the Clinical Implications?[bullet] Distinct large artery phenotypes have divergent etiopathological implications for cSVD. Our findings support a non-atheromatous, intrinsic microvascular pathology as the principal mechanism of lacunar stroke and cSVD. [bullet]Mechanism-based therapeutic strategies for lacunar stroke and cSVD, moving beyond conventional approaches focused on atherosclerosis or cardioembolism, are warranted.