[Platelet aggregation in vasomotor headache].

Employing optical density methods, platelet aggregation in response to increasing concentration of ADP was tested in 24 patients with migraine and 15 controls. The migraine patients don't demonstrate platelet hyperaggregability when compared with controls. Platelet aggregate ratio (P.A.R.) was measured in 13 patients and 15 controls by the method of Wu and Hoak: a significant difference was found between and controls. The hyperaggregability found here, even if only for the P.A.R., may help explain the increased incidence of stroke and heart attack in migraine patients that has been reported elsewhere.