Finding
Surgery may also be indicated for those patients who have such extensive occlusive disease that the over-all supply of blood to the cerebral pool is jeopardized.
Paper
Physiological considerations in cerebrovascular disease.
Abstract
Physiological and anatomical features of the cerebral vascular system already discussed explain why there is an inconsistent relationship between degenerative arterial disease in the major neck vessels and cerebral ischemia. It is probably the state of the smaller vessels at or above the circle of Willis which determines the site of an ischemic lesion not due to emboli.32,33 For example, when there is a stenosis of the carotid artery, infarction is much more likely in the ipsilateral middle cerebral artery territory if there is congenital hypoplasia of the posterior communicating artery on the same side. Disease above the circle of Willis is likely to have a profound effect on cellular perfusion, so that a marked reduction in cortex perfusion, especially if asymmetrical between the hemispheres, is good evidence of disease at or above the circle of Willis. It has been shown that atheromatous lesions in the carotid arteries have no constant effect on cerebral cortex perfusion rates34 and that removal of a stenosis, thought to be significant in terms of vessel blood flow, has no constant effect on cellular perfusion. From a small series in which pre- and postoperative cortex perfusion rates were estimated it would appear that those patients with markedly reduced or asymmetrical perfusion rates were less likely to profit from surgical intervention. An operation on the carotid bifurcation is much less likely to benefit the patient if the “final common pathway” of blood to the cells is severely compromised. Surgery is most suitable, therefore, for patients whose symptoms are likely to be due to emboli, who preferably have little or no persisting neurological deficit, and who also have no evidence of significant small vessel disease. Preliminary results suggest that cerebral blood flow measurements can provide additional information about the state of the small vessels and thus may be important in determining both prognosis and suitability for operation. Surgery may also be indicated for those patients who have such extensive occlusive disease that the over-all supply of blood to the cerebral pool is jeopardized. It should be borne in mind, however, that emboli are not the only cause of strokes or transient ischemic attacks in the presence of extracranial cerebral vascular disease and there may be surprisingly little neurological deficit in patients with only one patent vessel. This is illustrated by the case report by Gull10 which starts with the following sentence: “It scarcely seems credible that a person shall live in the enjoyment of her faculties and in comparative health, with all the major vessels of the head and neck, except the left subclavian, closed at their origin from the arch of the aorta”.
Authors
M. O’Brien
Journal
American heart journal