From: deputyfife23x@gmail.com   
      
   Migraine and Stroke - What's the Link?   
      
   by Viatcheslav Wlassoff, PhD | August 17, 2014    
      
      
      
   On the surface, strokes and migraines do not seem to have much in common   
   except that both of them can have serious psychological effects on the   
   sufferers. But researchers say that a complex relationship exists between the   
   two.   
   Migraine is a neurological disorder characterized by the occurrence of   
   throbbing and recurring headaches that can be so severe to interfere with the   
   normal day to day life. Stroke is a medical emergency caused by a compromised   
   blood supply to the brain.    
   It could result in brain damage, eventually leading to complications and   
   disability.   
   Several studies have associated migraine in young adults, especially women,   
   with ischemic stroke. A recent study relates migraine without aura in older   
   people with subclinical stroke.   
   Understanding migrainous aura and migrainous infarction   
   Migraine is a complex neurobiological disorder and the understanding of its   
   pathophysiology is still incomplete. Vascular and genetic pathology have been   
   attributed to this disorder. The condition commonly presents in two forms:   
   migraine with aura (MA)    
   and migraine without aura (MO).   
   The migrainous aura consists of transient focal neurological disturbances   
   presenting in the form of visual, sensory or motor symptoms that precede the   
   migraine headache. According to the description given by the International   
   Headache Society (IHS), the    
   aura develops gradually over a period of five minutes and it lasts less than   
   60 minutes. It occurs in up to 25% of migraine sufferers.   
   The migrainous aura was earlier suspected to be a vascular process   
   (constriction of blood vessels causing the aura and then a reactive   
   vasodilatation causing the headache). But later and recent evidences suggest   
   that the aura may be due to the generation    
   of slowly propagating electrical waves called Cortical Spreading Depression   
   (CSD) that pass through specific parts of the brain including the visual   
   cortex (that part of the cerebral cortex which processes visual signals) and   
   the part of the brain that    
   processes touch signals. This is the reason why aura is often felt as visual   
   disturbances (like seeing sparkles, zigzag patterns, colored and dark spots)   
   and tingling sensations. The CSD is triggered by hypoxic-ischemic stress and   
   it is modulated by    
   genetic and environmental factors.   
   Migrainous infarction refers to a cerebral infarction that occurs during the   
   course of a typical migraine attack. This may lead to stroke. A typical   
   migrainous infarction is actually rare and it is more common during attacks of   
   migraine with aura than of    
   migraine without aura. One third of the migrainous infarcts are observed in   
   the occipital lobe of the brain, thus explaining the cause for visual deficits   
   that follow the attack. The IHS has established strict guidelines for the   
   diagnosis of migrainous    
   infarction and for this diagnosis to be made, it is necessary that the other   
   possible causes of infarction be ruled out.   
   Migraine and ischemic stroke   
   Generally, migraine with aura is associated with an increased risk of ischemic   
   stroke, especially in young women. Most of the studies made a special mention   
   of the increased risk in women who use oral contraceptive pills and who smoke.   
   Though these    
   studies have proposed migraine to be an independent risk factor for stroke in   
   young women, fortunately, they also report that it is only the relative risk   
   that seems to be high (women with migraine aura have an increased risk of   
   developing ischemic    
   stroke when compared to women without migraine aura) but the absolute risk   
   (the overall likelihood of developing ischemic stroke) is actually small.   
   The actual mechanism for the increased risk of ischemic stroke in people with   
   migraine is not known. Various potential mechanisms have been hypothesized.   
   Cerebrovascular hypoperfusion induced by vasospasm can trigger CSD and this   
   neuronal spreading can    
   itself decrease the perfusion pressure and blood flow to the brain causing   
   ischemia. Increased platelet activation and aggregation and associated blood   
   coagulation abnormalities have also been attributed to the increased risk of   
   ischemic stroke in    
   migraine sufferers. Potential biological mechanisms like endothelial   
   dysfunction (dysfunction of innermost layer of blood vessels) and cervical   
   artery dissection (dissection of arteries in the neck) have also been   
   hypothesized.   
   All these conditions may lead to the formation of blood clots that can block   
   the blood vessels supplying the brain and cause stroke. Another hypothesis is   
   that the increased prevalence of patent foramen ovale (hole in the heart   
   leading to shunt) in    
   patients with migraine may lead to clot formation and thus stroke. However, it   
   has been difficult to explain a particular reason for the increased risk of   
   stroke in young women with migraine.   
   Studies suggest a higher risk of silent brain infarction in people with   
   migraine   
   A recent report suggests that migraine could serve as a risk factor for   
   sub-clinical brain infarctions leading to stroke in older people with   
   migraine. Researchers from the Northern Manhattan Study (NOMAS) reported that   
   migraine sufferers had twice the    
   risk of developing silent stroke when compared to people who did not report   
   migraine episodes. This finding related more to the people who experienced   
   migraine without aura. Having said that, a question arises as to what is a   
   silent stroke?   
   Silent stroke: unrecognized brain damage, without a warning   
   Silent stroke does cause permanent damage to the brain, but the damage is   
   small, subtle and goes unnoticed. The reason for this is that silent stroke   
   does not affect the main functional areas of the brain that lead to apparent   
   symptoms when damaged.    
   However, silent strokes can lead to cognitive disturbances and accumulation of   
   such subtle damages can lead to gradual neurological deficits.   
   Though the researchers from the NOMAS did not consider the risk of developing   
   stroke in migraine sufferers to be significant, the prevalence of silent brain   
   infarcts in these patients has raised concerns. The researchers have   
   emphasized the need for    
   reducing the risk factors of stroke in such people. Similar concerns were also   
   expressed in previous studies. Attention is especially needed to patients who   
   have co-existing vascular risk factors like elevated blood pressure, elevated   
   cholesterol level,    
   diabetes, coronary heart disease, etc.   
      
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