Migraine and stroke: the role of oral contraceptives.

The use of oral contraceptives (OCs) confers an increased risk for ischaemic stroke (IS). This risk slightly decreases, but remains significant, if low-dose formulations are used, particularly if other risk factors, such as hypertension or smoking, are associated. Some inherited prothrombotic conditions (e.g., Factor V Leiden, G20210A prothrombin or methylenetetrahydrofolate reductase C677T polymorphism) could also greatly increase the IS risk if present in OC users. Migraine, particularly with aura, is an independent risk factor for IS, and the patient's IS risk is probably affected by other individual risk factors (e.g., age, genetic predisposition to thrombosis, presence of patent foramen ovale or enhanced platelet aggregation) which seem to be over-represented in migraine patients. IS risk among migraineurs is further increased when OCs are currently used and can become very high if associated with smoking. Consequently, in 2004 the WHO stated in its 'Medical Eligibility Criteria for Contraceptive Use' that women suffering from migraine with aura at any age should never use OCs. Moreover, since the exposure to the effects of OCs may greatly increase the IS risk in some migraine subpopulations with specific personal characteristic, testing for these risk factors may allow for more accurate stratification of the population at risk before long-term use of OCs is prescribed.