Brain scaps lift a little the veils off throbbing headaches
RESEARCHERS in Germany recently provided some vital clues about migraine
and its origin by watching it in action.
Carnelius Weiller and his colleagues at
the University of Essen suggest that the
real source of a migraine attack lies in
the brain stem though the pain is experienced at the temples (New Scientist,
Vol 147, No 1985).
Using positron emission tomography (PET) brain scans, the scientists
examined volunteers who had
migraines on the right side of their
heads. Their cerebral blood flow was
measured. Seven sites in the brain were
lit up during the scans, indicating the
areas receiving the highest blood flow
and thus being the most active sites.
The procedure adopted involved
scanning patients within 6 hours of the
onset of a migraine attack. Thereafter, a
pain relieving drug, sumatriptan, was
administered and once the pain had
vanished another PET scan was conducted. These scans were then compared
with scans recorded when the volunteers had no headache.
Of all the 7 sites that the migraine
scan lit up, the only site that remained
active after the dose of surnatriptan had
relieved pain and other symptoms, was
in the brain stem - the junction
between the brain and the spinal cord.
Researchers are of the view that any
abnormal activity in this stem may trigger migraine. "It could also explain the
repeat attacks that can occur once the
effects of sumatriptan wear off," says Weiller.
Further, researchers discovered that
the largest increase in blood flow took
place between 2 small areas in the brain stem that are meant to control the constriction and dilation of blood vessels in the brain.
Moreover, blood flow in the brain
stem was found to be 'More on the opposite side of the site where the pain was
being felt. In other words, the patients
having right side headaches had the left
side of their brain stem active.
Researchers plan to study subjects with
left-side headaches now to see whether
they will have heightened activity in the
right side of the brain stem.
Unexpectedly scientists discovered
that migraine was accompanied by
heightened activity in centres for bearing
and vision; in addition the brain centre
associated with mood was also a hotspot.
Says Weiller, "Migraine sufferers are
typically very sensitive to noise and
light."
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