Furthermore, attacks of migraine, particularly with prominent neurologic symptoms, instead of beginning in childhood, may have their onset later in life, and Fisher provided support for the hypothesis that some of the transient aphasic, hemianesthetic, or hemiplegic attacks of later life may be of migrainous origin (“late life migraine accompaniments”). With careful questioning, many of these patients with TIA syndromes will recall a history of migraine headaches in youth.
The reported incidence of stroke complicating migraine has varied. At the Mayo Clinic, in a group of 4,874 patients, ages 50 years or younger with a diagnosis of migraine, migraine equivalent, or vascular headache, 20 patients had migraine-associated infarctions (Broderick and Swanson). Caplan described 7 patients in whom attacks of migraine were complicated by strokes in the vertebrobasilar territory. A study by Wolf and colleagues collected 17 instances of stroke and migraine. Most had a prolonged aura, either visual, sensory, or aphasic and over two-thirds of the strokes, demonstrated by diffusion restriction on MRI, were in the posterior circulation territory and occurred in younger women. There is, nonetheless, a paucity of useful pathology by which to interpret the mechanism of migraine-associated stroke. The uncertain but potential role of antimigraine medications in producing stroke is discussed further on in the section on treatment. Estrogen medications have also been implicated in stroke in some women migraineurs. The complex relationship between acute stroke and the use of triptans or ergots for the treatment of migraine is addressed in a later section.
In children and young adults with the mitochondrial disease MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) and in adults with the rare cerebral vasculopathy CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), migraine may be a prominent feature. Chapter 33 addresses these issues further.
The special problem of focal cerebral disorders associated with segmental or diffuse vasospasm, including the form that follows treatment with the “triptan” (serotonin agonist) drugs and Call-Fleming syndrome, is discussed further on in the section on treatment and under “Diffuse and Focal Cerebral Vasospasm” in Chap. 33.
Epidemiologic association between migraine and stroke A separate set of observations, mainly epidemiologic, pertain to the risk of strokes, particularly in women with migraine. Despite some variability in conclusions between studies, meta-analyses have suggested that there is a two-fold increase of lifetime incidence of ischemic stroke in individuals with migraine and aura (see, e.g., Spector et al). The risk may increase with increasing migraine attack frequency and particularly with oral contraceptive use and smoking, which together may confer a ninefold increase in risk. For example, in the Northern Manhattan Study by Monteith and colleagues, migraine was associated with future stroke but only in smokers. There may be a similar increase in cardiovascular events later in life but the evidence for this is uncertain and difficult to disengage from confounding risk factors. A meta-analysis of case control and cohort studies conducted by Schüks and colleagues were unable to demonstrate an increased risk for cardiovascular events. Other investigators, again depending on various population databases and few patient level studies, have come to the opposite conclusion (Bigal et al) and suggested that all cause mortality is increased in migraine patients (Gudmundsson et al). There are also emerging but tentative connections between genetic variants and shared risks for stroke and migraine.
The issue of oral contraceptives as a risk for stroke in migraineurs is a more complicated matter that has not been entirely resolved except that the risk may be greater in women who have migraine with aura. The pills are not entirely interdicted in migraineurs but several guidelines suggest against the use of oral contraceptives if there is migraine with aura. Perhaps lower estrogen compounds are advisable in migraine without aura as formulations with high estrogen concentrations have been associated with clotting in the venous circulation.