Abstract Body: Background: Dolichoectasia (DE) is characterized by the abnormal dilation and elongation of brain arteries, leading to high morbidity and mortality, commonly presenting as ischemic stroke. However, the mechanisms underlying brain ischemia in DE are not well understood. Here, we explore the relationship between basilar artery (BA) diameters and blood flow velocities using transcranial doppler (TCD) in stroke patients to evaluate whether TCD is a viable method for evaluating the hemodynamic impact of DE.
Methods: Using a cross-sectional design, we analyzed consecutive ischemic stroke patients admitted to a comprehensive stroke center from October 2017 to January 2018, who had completed both intracranial arterial imaging (CTA or MRA) and TCD during admission. Diameter of the BA was measured using semiautomatic vessel segmentation, and DE was defined as a BA diameter greater than the 95th percentile stratified by sex. TCD-derived blood flow velocities were recorded through the transforaminal window (depth 80-100mm). Linear regression models adjusted for age and sex were used to assess the association between BA diameter and averaged mean flow velocity (MFV). Subgroup analysis excluding cases with BA stenosis and fetal posterior cerebral artery (fPCA) was also performed.
Results: Among 211 ischemic stroke patients, 44 had vessel imaging and TCD. The mean age was 64 ± 13 years, 66% were male, 36% had posterior circulation stroke, 11.4% had BA DE, 21% had BA stenosis, and 16% and 11% had unilateral and bilateral fPCA, respectively. The mean BA diameter was 3.7 ± 2.1 mm, and the mean averaged MFV was 40 ± 21 cm/s. A weak negative correlation was found between BA diameter and MFV (r = -0.37, p = 0.01). The linear regression model adjusted for age and sex showed an independent negative correlation (β per mm = -3.33 [95% CI -6.2 to -0.5]). In the subgroup without BA stenosis and fPCA (n = 25), the negative correlation between BA diameter and MFV was stronger (r = -0.65, p < 0.01), with β per mm of -4.44 (95% CI -7.0 to -1.9; figure).
Conclusion: In ischemic stroke patients, larger BA diameters correlated with reduced TCD-derived blood flow velocities, particularly after excluding cases with fPCA and BA stenosis. Reduced blood flow velocities can lead to blood stagnation, thromboembolism, and hypoperfusion, suggesting that TCD may be useful for grading DE severity and assessing stroke risk.