Pharmacological prevention of migraine: to be considered case by case.

(1) Migraines are characterized by recurrent headaches generally lasting between 4 and 72 hours and disappearing without complication. They can be incapacitating, owing to their frequency and/or intensity. (2) Many drugs have been used to prevent migraines. One of the most common outcome measures used in clinical trials is the proportion of responder patients, defined as those in whom the monthly frequency of migraines is at least halved. On average, about one-third of patients respond to placebo in clinical trials. (3) Propranolol is the betablocker with the best-documented efficacy: in absolute terms the response rate is about 30% higher than with placebo. The adverse effects of betablockers are mainly cardiovascular and neuropsychological. (4) Valproic acid, an anticonvulsant, is about as effective as propranolol, and its adverse effects are generally acceptable. (5) Amitriptyline is the antidepressant with the best-documented preventive effects, with a response rate about 20% higher than placebo. Its principal adverse effects are due to its atropinic action. Amitriptyline can also have a sedative effect. (6) Flunarizine also has documented efficacy, but this "hidden neuroleptic" can cause extrapyramidal disorders and weight gain. (7) Among the serotonergic antagonists, methysergide has documented efficacy but long-term treatment can lead to serious retroperitoneal, pulmonary or cardiac fibrosis. Pizotifen causes drowsiness or weight gain in about 50% of patients. (8) The choice of preventive treatment for migraine must be based on the balance between efficacy (compared to placebo) and adverse effects. In practice, the first choice drug is propranolol. (9) Because the frequency of migraines fluctuates over time, withdrawal of prophylaxis should be attempted on a regular basis, with the patient's consent.