Neuropathology of white matter lesions in vascular cognitive impairment.

The white matter is an important locus for tissue damage in vascular cognitive impairment and white matter lesions often dominate over gray matter changes. The spectrum of ischemic white matter lesions histopathologically represents focal and diffuse lesions, the most common form being the combination of both, in varying proportions. In the combined pathology, the diffuse lesion represents a gradient zone of damage towards surrounding normal tissue and may hold over 200 times the volume of an identified focal lesion, the lacunar infarct. Pathogenetically, the focal lesion results from the acute reaction to regional ischemia, while the diffuse white matter lesion represents the adjustment to altered perfusional and physiological conditions within the tissue.