Remarks on spontaneous platelet aggregation after focal ischaemia experimentally induced in the rabbit

Within the framework of an investigation at present under way at the Neurological Clinic of Pavia on experimental focal ischaemia, the peculiarities of platelet aggregation observed, have led to a more accurate assessment of both the phenomenon itself and the validity of the method used. In a group of 30 rabbits (17 of them submitted to embolization by means of microspheres introduced into the carotid and 13 used as controls), biohumoral electrical and histological parameters were examined. The spontaneous platelet aggregation test proved significantly related to the extent of changes taking place, as measured by PDS levels and QEEG 'delta' activity (respectively, P <0.005 and P <0.05). Platelet aggregation, in relation to the occurrence or absence of focal ischaemia, revealed a 'sensitivity' of 80% and a 'specificity' of 92.3%. When not only the onset of but also the increase in aggregation is taken into account, the 'sensitivity' figure appears to go up to 93.3%. Endothelial damage and 'cascade' platelet aggregation appeared to be a prerequisite for the occurrence of the changes found. In these changes, the pathogenetic role of the regional vasospasm as opposed to mere mechanical obstruction seems to be confirmed. On the basis of these findings, it is concluded that the identification of spontaneous platelet aggregation using K. Breddin's method and its quantification based on Born's turbidimetric principle, may be usefully employed to assess the risk factor constituted by an abnormal tendency to platelet hyperaggregation.