Collateral status is not affected by the severity of disease even in the very elderly, according to a single-center study.
Small vessel disease (SVD) burden among patients with acute ischemic stroke of the anterior circulation does not appear to impact collateral flow, according to data from a single-center investigation of a restricted population. Still, the authors of the study, published online April 30, 2019, in Stroke, recommend that the impact of SVD burden on collateral flow deserves further evaluation.
“Small vessel disease may impair collateral flow in large-vessel occlusion treated by mechanical thrombectomy, [and] collateral flow status is a key factor for effective recanalization,” senior author Norbert Nighoghossian, MD, PhD (Pierre Wertheimer Hospital, Hospices Civils de Lyon, France), told Neurovascular Exchange in an email. “Increased resistance in the microcirculation may prevent the development of leptomeningeal collateral circulation,” he continued.
The investigators, led by Omer Faruk Eker, MD, PhD (Pierre Wertheimer Hospital), identified 240 patients (mean age 69 years; 49% female) admitted to their center for anterior circulation stroke between January 2013 and March 2018. All of the patients were treated by mechanical thrombectomy with or without thrombolysis and underwent baseline MRI. An SVD score ≥ 1 on MRI was considered severe. Pial collaterals were evaluated using the Higashida score, which was considered favorable when it was ≥ 3 on digital subtraction angiography.
Approximately half of the cohort had a cerebral SVD score of 0, 31% had a score of 1, 13% had a score of 2, and 5% had a score of 3. A favorable Higashida score was seen in 58% of the patients. Compared with those with an unfavorable Higashida score, those with a favorable score were more likely to be female (58% vs 38%; P = 0.002), have a lower baseline NIHSS score (mean 12 vs 17; P < 0.001), and have a higher DWI ASPECT score (mean 8 vs 6; P < 0.001).
No Association Found
Regression analyses revealed no impact of cerebral SVD score on the collaterality pattern (OR 1.11; 95% CI 0.82-1.50).
“In our study, the collateral status was not affected by the severity of the SVD burden, even in very elderly despite a known increased prevalence of risk factors for SVD,” Eker and colleagues write.
They question, however, whether limitations of the study may explain the results. These include its single-center design in a selected population with a limited infarct extent and a high proportion with low SVD burden, use of 1.5 T and 3.0 T MRI (which may have underestimated the number of cerebral microbleeds), and use of fluid-attenuated inversion recovery imaging instead of T2-weighted sequence (which may have underestimated perivascular spaces enlargement). They also failed to take into account the impact that previous TIAs might have had on SVD burden severity.
“Middle cerebral artery territory microvascular resistance assessment using sonographic measures (eg, pulsatility and resistive indexes) may provide additional quantitative data to explore the impact of the SVD burden,” Eker and colleagues write, adding, “Further studies coupling brain perfusion and morphological analysis might also be of interest.”
Such continued research is important, Nighoghossian told NVX, because it may help identify drugs that can “decrease microcirculation resistance in patients with significant SVD burden treated by thrombectomy, in order to prevent [the] no reflow phenomenon following recanalization.”
Eker OF, Rascle L, Cho TH, et al. Stroke. 2019;Epub ahead of print.
Nighoghossian reports no relevant conflicts of interest.