Temporal bone thickness and texture are independent predictors of TCD insonation failure in Amerindians.

Background: There is no information on transcranial Doppler (TCD) failures due to poor insonation among native inhabitants of Latin America. Methods: Seventy Ecuadorian natives and 70 age- and sex-matched individuals of European origin underwent TCD. The same investigators performed all exams using the same equipment and protocol. Using the McNemar's test for correlated proportions, we compared TCD failures related to poor insonation across ethnic groups. Results: Out of 140 participants, 56 (40%) had one or more suboptimal/absent acoustic windows. These persons were older (p = 0.01) and were more often women (p < 0.0001) than those with all optimal windows (irrespective of race/ethnicity). In the matched-pair analysis, Amerindians were more likely to have suboptimal/absent acoustic windows than individuals of European origin (OR: 2.8, 95% CI: 1.3-6.5, p = 0.006). Conclusion: Amerindians are almost three times more likely to have insonation failures related to poor acoustic windows than their European counterparts.

Background:Diagnosis of cerebral small vessel disease (SVD) is a challenge in remote areas where magnetic resonance imaging (MRI) is not available. Hospital-based studies in high-risk or stroke patients have found an association between the pulsatility index (PI) of intracranial arteries – as derived from transcranial Doppler (TCD) – and white matter hyperintensities (WMH) of presumed vascular origin. We aimed to assess the reliability of cerebral pulsatility indices to identify candidates for MRI screening in population-based studies assessing prevalence of SVD.Methods:A representative sample of stroke-free Atahualpa residents aged ≥65 years investigated with MRI underwent TCD. Using generalized linear models, we evaluated whether the PI of major intracranial arteries correlate with WMH (used as a proxy of diffuse SVD), after adjusting for demographics and cardiovascular risk factors.Results:Out of 70 participants (mean age 70.6 ± 4.6 years, 57% women), 28 (40%) had moderate-to-severe WMH. In multivariate models, there were no differences across categories of WMH in the mean PI of middle cerebral arteries (1.10 ± 0.16 vs. 1.22 ± 0.24, β: 0.065, 95% confidence interval (CI): −0.084–0.177, P = 0.474) or vertebrobasilar arteries (1.11 ± 0.16 vs. 1.29 ± 0.27, β: 0.066, 95% CI: −0.0024–0.156, P = 0.146).Conclusions:Cerebral PI should not be used to identify candidates for MRI screening in population-based studies assessing the burden of SVD.

Background In a population-based sampling study conducted in community-dwelling older adults living in rural Ecuador, we aimed to assess the relation among sleep-disordered breathing, cerebral pulsatility index, and diffuse small vessel disease. MethodsOf 25 participants, 9 (36 %) had moderate-to-severe sleep-disordered breathing, characterized by an apnea/hypopnea index ≥15 per hour, and 10 (40 %) had moderate-to-severe white matter hyperintensities, graded according to the modified Fazekas scale. Mean (SD) pulsatility index in the middle cerebral artery was 1.18 (0.19) and positively correlated with the apnea/hypopnea index (R = .445, P = .03, [Pearson’s correlation coefficient]). The middle cerebral artery pulsatility index was increased in persons with moderate-to-severe sleep-disordered breathing compared with persons who had none-to-mild sleep-disordered breathing (mean [SD] 1.11 [0.12] vs. 1.3 [0.23], P = .01). No significant differences were found in the prevalence of moderate-to-severe white matter hyperintensities across groups of sleep-disordered breathing (P = .40) or in the mean apnea/hypopnea index across groups of persons with none-to-mild or moderate-to-severe white matter hyperintensities (P = .16). ConclusionsThis pilot study shows that moderate-to-severe sleep-disordered breathing correlates with cerebral pulsatility, but such association might be independent of diffuse small vessel disease.