Cerebral microinfarcts: A systematic review of neuropathological studies

Abstract

Vascular cognitive impairment (VCI) is an umbrella term for cognitive dysfunction associated with vascular brain damage. Autopsy studies have identified microinfarcts as an important neuropathological correlate of VCI that escapes detection by conventional MRI. With the introduction of clinical ultra-high field strength MR scanners, it may be possible to detect microinfarcts in vivo. This systematic review of neuropathological studies on microinfarcts was performed as a frame of reference for future high-resolution MRI studies. We systematically reviewed the literature on neuropathological studies concerning microinfarcts in the context of vascular disease, vascular risk factors and cognitive decline and dementia. We identified 29 eligible studies involving 10193 people. The overall picture was that microinfarcts were common in non-demented individuals (weigthed average 20%), but had a higher prevalence in patients with vascular dementia (62%), Alzheimer's disease (44%) and demented patients with cerebrovascular disease (32%). In many patients multiple microinfarcts were detected, despite the fact that only a relatively small proportion of the brain was sampled and examined microscopically. Microinfarcts were described as minute foci with neuronal loss, gliosis, pallor or more cystic lesions and they were detected in all brain regions, possibly more so in the cerebral cortex and in watershed areas. Reported sizes varied from 50 μm - 5 mm Based on the histopathological features of microinfarcts and their size these lesions should be within the detection limit of current high field strength high MRI.