Believe it or not, there is a real scientific name for “brain freeze” – it is sphenopalatine ganglioneuralgia (try saying that 5 times fast!) When something very cold (usually ice cream) touches the top palate of the mouth, it causes the blood vessels to constrict. This makes the nerves send a signal to the brain to re-open them. The rapid re-opening of the vessels causes a build up of fluid in the tissues causing a slight swelling in the forehead and, therefore, causing pain. It normally takes 30 – 60 seconds for the fluid to drain, relieving the pain.
For more wild facts about brain freeze, go to listverse.com.