Page 17 - Migraine, the heart and the brain

The association between migraine and both silent infarcts and white matter lesions 1 can be spurious (associations in which the association is actually caused by bias),
causal (migraine as an independent risk for ischemia, or ischemia as a cause of
migraine), or migraine and ischemia are connected by a confounder. This confounder
may be a genetic factor, for example speci c genes could predispose one to both suffering from migraine and cardiovascular disease. The occurrence of both migraine aura and ischemic strokes and deep white matter lesions due to a genetic cause is for example seen in patients with CADASIL. In CADASIL migraine with aura can be the rst symptom, at a mean age of 30 years, whereas ischemic stroke and transient ischemic attacks occur at a mean age of 47 years.31 Other confounders might be vascular anatomical variants which have been described more frequently in migraine with aura, like posterior circle of Willis anomalies32 or right-to-left shunts.33 These anatomical variant will be explained in more detail in part II of this introduction. The results of the CAMERA-II study, focusing on the relation between migraine and progression of ischemic brain lesions will be described in Chapter II.
In summary, the baseline part of the population-based CAMERA-study showed migraine to be associated with subclinical infarcts in the cerebellum as well as infra- and supratentorial T2 hyperintense lesions, the latter however only among females. Although an association between attack frequency and lesion load had been suggested, only a longitudinal design could further evaluate a cause-consequence relationship of this association. It is unknown whether migraine characteristics (aura, attack frequency, medication use) correlate with an increased lesion load over the years. This will be addressed in Chapter II. Furthermore, it was suggested that other comorbid conditions might play a role, such as the presence of a right-to-left shunt of the heart. This will be explained in detail in the following paragraph.
ii. migraine and the heart and its relation to isChemiC brain lesions
Right-to-left shunts
Since 1998, several clinic based case-control studies have reported a two to three times increased prevalence of right-to-left shunts (RLS) in migraine with aura subjects compared to controls and subjects with migraine without aura.33;36 A RLS is an abnormal communication between the systemic right (venous) circulation and
Introduction
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