Surgical Treatment of Extracranial Atherosclerotic Lesions
Extracranial atherosclerotic lesions have long been treated with carotid endarterectomy and various arterial bypass graft procedures. The bypass procedures have been proven to provide no beneficial effect in prevention of stroke recurrence. However, the EC/IC bypass study raised serious questions and admonitions against the traditionally accepted belief that stroke can be prevented by simply restoring loss of blood flow in the brain. Moreover, the randomization of structural abnormalities, such as angiographie abnormalities, may not be enough to predict outcome of functions. The carotid endarterectomy may follow the same fate if future studies are designed to randomize stroke patients solely upon the degree of carotid stenosis and ulcération by angiogram. It is well known that results of many randomization studies contradict each other. This may reflect inadequacies in factors randomized, or incapability of these structural randomizations in prediction of functional outcome. The latter may be analogous to so-called used car evaluation pessimism. The pessimism relates to the difficulty in predicting durability of the car, even with the most elaborate mechanical and structural evaluation. The mechanical and structural evaluation does not include the handling and the maintenance of the car, which can be more decisive in determination of the prognosis of the car. No such functional factors are randomized in stroke studies, such as physical activities, psychological stresses, personal characteristics, socioeconomic status, working conditions and hours, and many others. Accordingly, in order to have the current randomization method be able to overcome the pessimism, the mechanical or structural abnormality has to be analysed with more precision and should be presented in such a way as to include reflection of some of the functional aspects. In addition, the mechanical factors have to be more grave than the functional factors.
KeywordsCerebral Blood Flow Carotid Endarterectomy Carotid Stenosis Carotid Plaque Carotid Bifurcation
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