Page 15 - Migraine, the heart and the brain

1) Are the lesions a consequence of repeated migraine attacks? If so, does 1 age at onset, duration of attacks or migraine subtype (with or without
aura) influence the amount of these lesions?
2) Is there a causal relationship between migraine attacks and brain lesions or is the increased risk eg. due to increased co-morbidity of other risk factors for brain ischemia? For example are cardiac right-to- left shunts, which were more prevalent among migraineurs in clinical based studies, related to these brain lesions?
3) What are the consequences of ischemic brain lesions for migraine patients? Are these lesions associated with any functional impairment?
These questions asked for a longitudinal (population) based study and additional investigation of cause and consequences. Before coming to the aims of this thesis the current knowledge on these topics will be addressed in the following three paragraphs of this introduction.
i. relation betWeen migraine and isChemiC brain lesions
Silent brain infarcts
The CAMERA-I study demonstrated that migraine subjects from the general population had signi cantly more often silent infarcts in the posterior circulation. This risk was increased more than seven times, notably in migraine with aura (Odds ratio (OR 12.9 (95% CI 1.6-101)), adjusted for age and sex.18 In the original publication18 the term “infarct-like lesions” was used, because we had no direct proof that the lesions were true infarcts. However based on a recent radiological-histological correlation-study we can now use the term “infarcts”.20 The large population based Reykjavik study con rmed the higher prevalence of posterior circulation infarcts among migraineurs by following 1996 men and 2693 women for 26 years and showing that migraine with aura in midlife was associated with late-life silent infarcts (OR 1.4, 95% CI 1.1-1.8), mainly in women. These silent infarcts were located more frequently in the cerebellum (OR 1.9, 95% CI 1.4-2.6) compared to women without headache.21 In addition, in the population based Vascular Aging study, which included 780 subjects between 60-70 years of age, a history of migraine with aura was associated with silent brain infarcts (OR 3.4, 95%CI 1.2- 9.3).22 In that study however, silent infarcts were predominantly located outside the cerebellum. Although these studies like the CAMERA-I study were population based, the MRI data was also only cross-sectional, so no causal relationship could be established.
Introduction
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