Rheological Behavior of Platelets in Situ in Middle Cerebral Artery Occlusion

Abstract

The observation of platelet microemboli in the retinal artery of a patient with amaurosis fugax by Fisher [4] led to serious consideration of the role of platelets in transient ischemic attacks and also in cerebrovascular diseases by many investigators and clinicians in this field. Thus, platelet functions in patients with cerebrovascular diseases have been the subject of much study and discussion in recent years [1]. Increased platelet aggregability and adhesiveness have been demonstrated in patients with stroke by many investigators [6, 10, 13, 14]. Most of these studies, however, were performed with an in vitro platelet aggregation technique which has been criticized as having serious limitations as a test for the measurement of in vivo platelet activity [2]. On the other hand, it has been suggested that cerebral ischemia itself stimulates the formation of platelet aggregates, which could contribute to the ischemic process [3]. Thus the role of platelets in the pathogenesis of occlusive cerebrovascular diseases may have two stages: one as a cause of thrombotic or embolic occlusion of the cerebral vessel, the other as a factor in the disturbance of microcirculation after the occlusion of the cerebral artery.