Cortico-subcortical distribution of microbleeds is different between hypertension and cerebral amyloid angiopathy.

BACKGROUND: The cerebral distribution of microbleeds in cerebral amyloid angiopathy (CAA) is quite different from that in hypertension, i.e., microbleeds in central gray matters are frequently found in patients with advanced hypertension (aHT), but not in patients with CAA. Distributions within the cortico-subcortical (CSC) area have not been compared between the diseases, and remain poorly understood.

OBJECTIVES: We hypothesized that distributions of microbleeds differ in aHT and CAA even in the CSC area.

METHODS: Out of a consecutive series of patients with intracerebral hemorrhage who underwent brain MRI (n=181), we selected typical aHT and CAA patients by inclusion criteria. Microbleeds in the CSC area were localized according to anatomical divisions and vascular territories. Numbers of microbleeds in these areas were counted and statistically compared.

RESULTS: A total of 52 hemispheres (aHT, n=32; CAA, n=20) were analyzed. The number of CSC microbleeds was higher in the CAA group (47.6+/-56.8) than in the aHT group (17.4+/-27.4; p=0.01). The microbleeds showed a significant predilection for the temporo-occipital lobes in the aHT group, but for the parietal lobe in the CAA group. The most involved vascular territory was middle cerebral artery territory in both groups, but the lesion number in anterior cerebral artery territory was relatively high in the CAA group.

CONCLUSIONS: In this study sample, aHT and CAA show different topographical microbleeds distributions, even in the CSC area. Our results suggest that the CSC microbleeds may reflect different pathophysiological mechanisms between aHT and CAA.