22 July 2005

Brain Freeze -- Ice-Cream Headache

Many, perhaps a majority of people, have experienced the sharp, brief head pain that comes from eating cold foods fast. Foods such as ice cream, frozen crushed-ice drinks such as a 7-Eleven Slurpee®, a frozen margarita, or an iced coffee. This is called "ice-cream headache", "ice cream evoked headache", "cold-induced headache", "cold-stimulus headache", or just "brain freeze". (7-Eleven registered the term “brainfreeze” in 1994.)

This phenomenon has been scientifically studied. In fact, it is the subject of one of the best sceintific papers I have ever read: Kaczorowski and Kaczorowski, "Ice cream evoked headaches (ICE-H) study: randomised trial of accelerated versus cautious ice cream eating regimen" BMJ. 2002 December 21; 325(7378): 1445–1446. The subjects were Ontario, Canada, schoolkids (all volunteers). The researchers did not report the flavours of ice cream administered.

The Science of "Ice-Cream Headache"

Place ice cream here:
picture of mouth
Most of what you read on the web about "brain freeze" says that stimulation of the trigeminal nerve causes dilation (expansion) of blood vessels in the head, which causes the pain. This vasodilation theory is related to an old theory of how migraine headaches are caused. It is also possible that the pain is from stimulation of the trigeminal nerve itself, and that the vasodilation is a response caused by chemicals released from the affected nerves. There may be misregulation or misinterpretation of messages along the trigeminal pathway. Some researchers have seen similarities between ice-cream headache and migraine, while others have not. However, the quick onset and short duration of ice-cream headaches suggest (to me, at least) a different cause than migraine.
Idiopathic stabbing headache (ISH) and ice cream headache occur due to paroxysmal firing of trigeminal pathways and a defect in pain control mechanisms. Due to the widespread distribution of ISH in the head, there might be irritation of various branches of the trigeminal nerve, while the restricted localizations of ice cream headache suggest irritation of a certain branch or branches of the trigeminal nerve, e.g. in the oropharynx. Either widespread or restricted irritation of trigeminal pathways causes either ISH or ice cream headache, in which intermittent deficits in central pain control mechanisms seem to be playing the key role. (From this abstract.)

I find it interesting that not all of us experience this type of headache. A survey of Taiwanese junior-high-school students indicated that about 40% experienced "ice-cream headache". Does this indicate that our brains are wired a little differently, or that our nerves are more or less susceptible to these "intermittent deficits in central pain control mechanisms"?

If you are susceptible, the trick is to minimize the contact between the cold stimulus and the posterior palate and/or posterior pharyngeal wall. Or eat your ice cream slower.

Further Comments:

This topic was suggested by Terry McElhaney (tmcelhaney@ricochet.com).

A good summary and discussion of ice-cream headache is here.

The picture is in the public domain. Source: https://secure.wikimedia.org/wikipedia/en/wiki/File:Tonsils_diagram.jpg.

Trigeminal Nerve

Everything is connected to everything else! The trigeminal nerve was also at the core of an earlier post about sneezes.

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1 comment:

Anonymous said...

I'm one who has never suffered from brain freeze. I thought I might add a potential piece of interesting data, even if only anecdotal. Speaking with others who also do not experience brain freeze, we all had a different physiological response to eating cold foods. We had a relatively painful reaction to cold in our throats as opposed to our heads. Although we have never performed a quantity-speed comparison test with those who get headaches, it might be interesting if someone someday researches whether or not we experience the throat-freeze (and thus slow down our eating, because it IS painful) before we hit the cold threshold that would cause brainfreeze.