Platelet activity in cluster headache.

Platelets are known to be activated in common or classic migraine both during the attack and in headache-free periods. Platelet behavior is less well known in cluster headache. We have investigated beta-thromboglobulin (beta-TG) and platelet factor four (PF4) plasma levels, markers of in vivo platelet activation, in patients during remission and during bouts of cluster headache with and without pain. The results indicated that statistically significantly higher levels of beta-TG and PF4 occur in the patients during the remission period when compared with the control subjects. Such high levels seemed to persist between paroxysmal episodes in cluster periods. However, during the attacks of cluster headache beta-TG and PF4 plasma levels decreased by 42% and 50%, respectively, in comparison with plasma concentrations measured outside of attack. Thus, although platelet activation also occurs in patients with cluster headache, the attack as such seems to be characterized by a marked reduction in platelet activation.