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New Data on the Relation Between Ischemic Stroke and Migraine

Contrary to established criteria, this study suggests that stroke can be a complication not only of migraine with aura, but also of migraine without aura.

These investigators analyzed the features and presumed causes of ischemic stroke in 130 patients with active migraine according to International Headache Society (IHS) criteria. Patients were identified from a prospective registry of 3502 patients with ischemic stroke. The researchers divided the migraineurs into 2 age groups (<45 and 45) and compared them to 2 control groups (with comparable average ages) from the stroke registry.

Of the migraineurs, 27 (21%) developed the stroke during a migraine attack, a condition known as complicated migraine. According to IHS classification, complicated migraine occurs only in attacks of migraine with aura. This study, however, proves the IHS classification wrong, because 59% of the 27 strokes occurred during attacks of migraine without aura. Isolated homonymous hemianopia was significantly more common among stroke patients with migraine than among stroke patients without migraine (12% vs. 5%, P<0.05).

Comment: In my clinical experience, as in this study, complicated migraine is more common during attacks of migraine without aura than during migraine with aura. This finding suggests that such strokes are not a consequence of the mechanism of migraine aura going awry, as is generally assumed. In my opinion, they are, rather, due to runaway migraine attacks, in which excessive activation of the sympathetic nervous system (SNS) and dehydration increase the risk for ischemic stroke. Excessive SNS activation occurs because of prolonged, severe pain and results in arterial vasoconstriction and blood platelet activation. Dehydration that is due to lack of fluid intake, vomiting, and, sometimes, diarrhea increases stroke risk in the same way that excessive alcohol intake does.

Stroke in complicated migraine typically involves the territory of the posterior cerebral artery, resulting in homonymous hemianopia (Headache 1990; 30:727), which in this study was more common in stroke patients with migraine than in those without migraine. The authors only briefly acknowledge this point, yet it is essential to understanding the mechanism of complicated migraine. The posterior cerebral artery may have more pronounced sympathetic innervation and, as a result, may be more strongly affected by SNS-induced vasoconstriction. The more pronounced sympathetic innervation may exist to compensate for decreased autoregulation at the microcirculatory level within the posterior lobes; this decreased autoregulation is known to make that brain region more vulnerable to hypertension-induced posterior leukoencephalopathy (see Spierings ELH. Acute and chronic hypertensive headache and hypertensive encephalopathy. Cephalalgia 2002; 22:in press).

— Egilius L.H. Spierings, MD, PhD

Dr. Spierings is Associate Clinical Professor of Neurology, Harvard Medical School and Brigham and Women's Hospital, Boston.

Published in Journal Watch Neurology March 8, 2002

Citation(s):

Milhaud D et al. Ischemic stroke and active migraine. Neurology 2001 Nov 27; 57:1805-11.

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