1982 Volume 19 Issue 6 Pages 571-576
Platelet aggregability was estimated in patients with cerebral infacrction (68 cases in the acute stage and 74 in the convalescent stage) and crebral hemorrhage (46 cases in the acute stage and 45 in the convalescent stage). The “acute stage” was difined as a period within a week after the onset of stroke, and the “convalescent stage” after four weeks. Platelet aggregability was evaluated on the basis of threshold concentrations of adenosine diphosphate (ADP) to induce the secondary aggregation. Patients were divided into three groups. In type I (lower sensitivity) secondary aggregation was seen after adding 4μM ADP, type II (moderate sensitivity) 2μM and type III (higher sensitivity) 1μM.
In the acute stage of cerebral infarction and hemorrhage, the platelet sensitivity to ADP-induced aggregation was significantly lower than in the convalescent stage. When platelet aggregability was monitored continuously from the acute stage to the convalescent stage, the aggregability tended to enhance later, especialy in the cases with infarction of the carotid system, but this was not seen in the cases with infarction of the vertebro-basilar system.
It might be considered that a lower sensitivity of platelet to ADP in the acute stage was due to the circulation of exhausted platelets. This fact should be taken into account when platelet suppressing therapy is cons idered in acute phase of cerebral infarction. When aggreganility of platelet in chronic phase was evaluated with reference to patients' age, type III was more frequently seen in older group (>65y.o.). This suggests that platelet aggregability may enhance with age.
