The Dangers of Incomplete Network of Arteries in the Brain
[ScienceDaily: Migraines associated with variations in structure of brain arteries]
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| Complete Circle of Willis |
Migraine is a primary headache disorder that mainly
affects one of half of the head. There is no definite theory to fully explain
the exact causes of migraine but known several symptoms: frequent changes in
mood or sensation, visual or auditory disturbances, and headaches. University
of Pennsylvania School of Medicine claims that the variations in arterial
anatomy lead to asymmetry of the cerebral blood flow that triggers migraines.
The ideal cerebral blood flow would be the complete circle of Willis, which
portrays a definite symmetry. In the incomplete circle of Willis, there is an
absence of anterior communicating artery and posterior communicating arteries. As
the migraine patients were likely to have incomplete circle of Willis, according
to the magnetic resonance angiography, the scientists induced that the
fundamental cause of migraine may be associated to the incompleteness of the
circle of Willis.
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| B: Complete Circle of Willis C: Incomplete Circle of Willis © University of Pennsylvania School of Medicine |
Circle of Willis is the arterial anastomosis at the
base of the brain, which covers over 80% of the cerebrum, supplying blood to
the brain. The incomplete circle of Willis can lead to abnormal neuronal
signals owing to the structural alterations of the blood supply. In fact, there
is a study illustrating the relationship between measurements of blood
oxygenation and neuronal activity. In other words, in the change of the brain
vessel structure, the blood flow will also change, and hence the oxygen
saturation in asymmetrical circle of Willis will lead to changes in the
neuronal activity. Also, migraine suffering patients showed absence of anterior
communicating artery and posterior communicating arteries.
Anterior communicating artery is especially closely
located to the optic nerve. The absence of such artery could cause degradation
of neural optic signals, which explains the visual disturbance – main migraine symptoms.
Posterior communicating arteries are the lower half of the circle of Willis.
This joins the basilar artery, which divides into two vertebral arteries. The
absence of these arteries will fail to supply oxygenated blood into the occipital
lobe, which is the visual processing center.
KSJ
