| Abstract: | The hypothesis that abnormalities of platelet function may relate to the occurrence or recurrence of subarachnoid hemorrhage (SAH) has been examined. Seventy patients with SAH and 65 control individuals were studied. The adenosine diphosphate (ADP) threshold for secondary platelet aggregation was significantly higher in the SAH group than in the controls. In tests using 4.0 micrograms/ml ADP, the percent platelet aggregation (at 2 minutes) and the maximum rate of platelet aggregation (over 20 seconds) were significantly lower in the SAH patients. There was no difference in total platelet count between the two groups. Platelet adhesiveness was lower in the SAH patients when compared to controls. Circulating microaggregates did not differ between the two groups. The results indicate that reduced platelet function does relate to SAH and may either contribute to aneurysmal rupture in cases of SAH or be a consequence of it. |
