Remote morphological changes in the white matter after ischaemic stroke.

Acute phase of stroke is the focus of most experimental and clinical studies on cerebral ischaemia. The scarcity of data on remote changes led us to examine the morphological pictures of brains after ischaemic insults. We paid special attention to the white matter capillaries. We microscopically evaluated 10 brains of patients who died after one month to fourteen years after the ischaemic stroke. Morphological examinations involved the application of routine histological stains and immunohistochemical reactions with antibodies against human albumin, GFAP, macrophage antigen CD 68 and lectins (Ulex europaeus, Wheat Germ agglutinin and Bandeirea simplicifolia). The results showed a swelling of the endothelial cells and their invagination into the vessel lumen. Postapoplectic cavities and white matter spongiosis decreasing with increase in distance from the cavity were observed. Immunohistochemical study showed that there was no segmental immunoreactivity to lectins on the capillary wall. Immune reaction to albumin revealed protein extravasation to the rarefied brain parenchyma. Our results indicate that progressing damage of the white matter after ischaemia may be caused not only by degeneration of axons of neurones destroyed by stroke, but also by pathological changes in small blood vessels, especially in capillaries. Hence, vascular leukoencephalopathy is probably caused by arteriolar damage as well as by microangiopathy.