Platelet count, mean platelet volume and their relation to prognosis in cerebral infarction.

The study was performed on patients with ischaemic cerebral infarction in order to obtain information on serial changes of some platelet parameters and to test their prognostic significance. Platelet count, obtained within 48 h after cerebral infarction, was significantly lower than in the control group (213,611 +/- 65,652 mm-3 vs. 299,525 +/- 60,611 mm-3, P less than 0.001), reaching the normal level on the ninth day and thereafter. The mean platelet volume was significantly greater than in the controls (11.26 +/- 1.29 fl vs. 8.93 +/- 0.93 fl, P less than 0.001), and normalization generally occurred on the forty-fifth day. The mean platelet count was significantly lower in the patients who died than in those who survived (P less than 0.025 and P less than 0.05 respectively on the first to second and fourth day after infarction). The reduction of platelet count and the increase of mean volume appear to be related to an increased platelet consumption in the infarction area, associated with an in vivo platelet activation, as larger platelets are more responsive to platelet activity and aggregability tests. The lower mean platelet count observed in the patients who died suggests that the platelet value might be considered as a prognostic index of cerebral infarction.