The Significance of Cortical Cerebellar Microbleeds and Microinfarcts in Neurodegenerative and Cerebrovascular Diseases

Abstract

Background: As cortical microbleeds and microinfarcts in neurodegenerative and cerebrovascular diseases have been studied predominantly at the level of the cerebral hemispheres and linked to the presence of cerebral amyloid angiopathy (CAA), we aimed at determining with 7.0-tesla magnetic resonance imaging (MRI) whether the causes and the frequency of cortical cerebellar microbleeds (CCeMBs) and microinfarcts (CCeMIs) are the same. Materials and Methods: Hundred and four postmortem brains, composed of 29 with pure Alzheimer's disease (AD), 9 with AD associated to CAA, 10 with frontotemporal lobar degeneration, 9 with amyotrophic lateral sclerosis, 10 with Lewy body disease, 12 with progressive supranuclear palsy, 9 with vascular dementia (VaD), and 16 controls, were examined. On a horizontal section of a cerebellar hemisphere examined with 7.0-tesla MRI, the number CCeMBs and CCeMIs were compared between the different disease groups and the control group. The MRI findings were also compared with the corresponding mean values observed on histological examination of a separate standard horizontal section of a cerebellar hemisphere, used for diagnostic purpose. Results: CCeMBs and CCeMIs were only significantly increased in the VaD group. When comparing the diseased patients with and without CAA mutually and with those with arterial hypertension and severe atherosclerotic cerebrovascular disease, only in the latter an increase of CCeMBs and CCeMIs was observed. There was an excellent correlation between the MRI and the neuropathological findings. Conclusions: CCeMBs and CCeMIs are mainly due to atherosclerotic cerebrovascular disease and not due to CAA. Their increased presence cannot be included to the Boston diagnostic criteria for CAA.

Frequency and topography of small cerebrovascular lesions in vascular and in mixed dementia: a post-mortem 7-tesla magnetic resonance imaging study with neuropathological correlates

“…Cortical microinfarcts predominate in the frontal lobe and in the cerebellum of VaD as cerebral arteriosclerosis is their main cause [8,18], while according to the validated Boston criteria for CAA, they predominate in the occipital lobe in MixD [10]. The same is also observed for CoMBs, although also A B Table III.…”

The topography of cortical microbleeds in frontotemporal lobar degeneration: a post-mortem 7.0-tesla magnetic resonance study

“…The prevalence of CoMBs and the white matter changes in FTLD brains should not be considered as the hallmark of cerebrovascular diseases. Also the increased iron accumulation observed in the basal ganglia of brains with FTLD should not be related to small-vessel ischemic disease [13] as recently proposed [18]. The fact that the CoMBs prevail in the regions with the most prominent neurodegenerative lesions indicates that blood-brain barrier impairments may interact with the severity of the neurodegeneration in FTLD and are secondary phenomena without impact on the clinical features of the disease.…”

Neuropsychological Features of Microbleeds and Cortical Microinfarct Detected by High Resolution Magnetic Resonance Imaging

“…In the elderly, CMIs have been mainly attributed to CAA [6]. To some extent, CAA is always present in AD brains and therefore, CMIs can be frequently observed in AD brains, especially in association with CAA [41]. As for the mechanisms of cognitive dysfunction, CMIs may directly damage the surrounding structures [42], but it is more likely that CMIs may represent an advanced stage of small vessel changes and its related blood-brain barrier disintegration and brain atrophy, because the observed finding for CMIs is only the tip of iceberg found in pathological specimens.…”