Pathologie-biologie
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Five beta-blocking agents are effective as long-term prophylactic treatment of migraine: propranolol, metoprolol, timolol, atenolol and nadolol. Propranolol has been most extensively studied and proved effective in 19 of 21 controlled trials. ⋯ Among the properties of beta-blockers, the only one which appears to be correlated--albeit negatively--with effectiveness on migraine is intrinsic sympathomimetic activity (ISA): drugs without ISA are effective against migraine whereas partial agonists are not. The mode of action of beta-blockers in migraine is still poorly understood; one of the most cogent current hypotheses involves reduction of brain catecholaminergic hyperactivity.
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Platelet function studies in migraine patients have evidenced a number of anomalies (hyperreactivity and serotonin metabolism disorders) that have been suggested as causative factors in migraine attacks. However, a review of the literature shows that these disorders are inconsistent and are probably consequences rather than causes of the headache, although they may contribute to the pathophysiology of the attack. From a broader perspective, the demonstration of platelet dysfunction in migraine raises questions as to the source of these disorders (secondary to plasma factors or due to platelet anomalies) and their significance (do they have any link with transient ischemic attacks or central serotonin neurotransmission dysfunction?).