Troubles tend to come in twos
and threes, and illness seems to fit this statement to
a T. Migraines are no exception but just in case any doubts
remain, it has been established that these patients are
much more likely to suffer an ischemic stroke when compared
to the general population.
A meta-analysis of 14 studies,
published online December 20 in the BMJ, found
that the risk of stroke is 2.16 times higher in people
who get migraines. The risk is further elevated in those
who experience an 'aura,' such as visual blurring or
a halo of light around objects, either during or immediately
before their headaches. These unfortunate souls, the
study said, run a risk of stroke that's 2.27 times higher
than people who don't suffer migraines.
These findings are actually quite
modest compared to some studies, which have estimated
up to a threefold higher risk for migraine sufferers
without aura and an alarming eightfold increase in sufferers
with aura.
GAINING
CONSENSUS
Although this phenomenon has been observed in the past,
the BMJ meta-analysis represented the consensus
of 25 years of migraine research. There was remarkable
unanimity between the three cohort studies and the 11
case-control studies reviewed.
Another widely suspected link that
this study confirms is that between stroke risk and
the contraceptive pill. Migraine sufferers who take
the birth control pill were found to run a risk of stroke
nearly nine times higher than age-matched subjects without
those two risk factors.
Lead author Dr Mayhar Etminan,
of the Royal Victoria Hospital at Montreal's McGill
University, said the importance of this finding could
easily be overstated. "The risk of stroke in a young
otherwise healthy person with history of migraine is
still very small, say four per 100,000 person-years.
Those who have cardiovascular risk factors for stroke,
are a bit older (45), smoke, take the pill and have
migraine may run slightly higher risks, but not to the
point of needing antithrombotic therapy," Dr Etminan
admitted, though he would advise those in the latter
category to be on the alert. "They may want to be a
bit more cautious and learn the symptoms of stroke."
He notes that the stroke link doesn't
actually prove that migraine causes stroke. It could
mean that risk factors for stroke, or a genetic predisposition,
also increase the risk of migraine. "I think our study
should prompt future studies to look and see whether
the risk factors for stroke — high cholesterol,
hypertension, and so on — may also be the same
risk factors in migraine."
BMJ published online Dec
20, 2004
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