Note the old cystic infarct in one caudate nucleus, putamen, and anterior limb of the internal capsule. This infarct is probably due to small artery arteriosclerosis. Infarcts are due to the occlusion of an artery of the Circle of Willis or one of its branches or a vein by a thrombus or embolus. Atherosclerosis is the major cause of cerebral vascular disease causing thickening and partial or complete occlusion of arterial lumina leading to thrombosis, due to low flow or sudden expansion of the arteriosclerotic plaque by hemorrhage or rupture of the plaque. Emboli arise from diseases of the heart with thrombi on abnormal heart valves or mural thrombi over areas of transmural or subendocardial myocardial infarcts.
Cerebrovascular disease is the third leading cause of death after heart disease and cancer.
Old infarcts appear as cystic spaces of varying size, depending on the size of the artery occluded, which contain portions of blood vessels and glial fibers. May also show some loss of myelinated fibers and neurons in the surrounding tissue. Clinically an infarct appears as the sudden onset of loss of function in a focal area such as a hemiparesis. When the infarct is old, depending on its size, the patient may have a fixed deficit if the lesion is large or in a main tract or may have very little neurologic deficit if it is small or away from tracts. Poirer J et.al.