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cwnboy2008

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[交流] 吃雪糕为什么会头痛

We Finally Know What Really Causes Ice Cream Headaches

Everyone's experienced that sharp, shooting headache as a result of stuffing their face with ice cream. Previously, scientists have suggested it's just a result of the rapid cooling and rewarming of blood vessels in the sinuses—but a new study shows that the cause is actually buried much deeper.

The research, carried out in part by Harvard Medical School, used trans-cranial Doppler imaging to study blood flow in the brains of patients while they had ice cream headaches—sometimes referred to as brain freeze—induced using iced water. They also performed the experiment with normal water as a control.

The results, which are being presented at the Experimental Biology 2012 conference, show that brain freeze is accompanied by a rapid dilation of the anterior cerebral artery, which floods the brain with blood and in turn causes pain. When the vessel constricts, patients report that the pain disappears. The researchers speculate that it's a form of self-defense for the brain:

"The brain is one of the relatively important organs in the body, and it needs to be working all the time,... It's fairly sensitive to temperature, so vasodilation might be moving warm blood inside tissue to make sure the brain stays warm."

They also explain that, because the skull is rigid, an increase in blood volume in the brain causes an increase in pressure, which is what induces the pain.

While it's neat to get a better understanding of what causes those nasty ice cream headaches, the findings could prove far more useful than that. The researchers point out that similar blood flow alterations could be behind migraines and other types of headaches. If that's the case, targeting headaches with drugs that can specifically affect dilation of blood vessels could bring a lot of relief to an awful lot of people.
from:
http://gizmodo.com/5904298/we-fi ... ice-cream-headaches
http://en.wikipedia.org/wiki/Ice-cream_headache
http://www.mayoclinic.com/health/ice-cream-headaches/DS00640
http://zh.wikipedia.org/wiki/%E5 ... C%E5%A4%B4%E7%97%9B

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