HEALTH - The "Ice Cream Headache"

"What causes brain freeze? Study reveals new clues" by Ryan Jaslow, CBS News 4/23/2012

We've all been there before: On a hot day, you reach for an ice cold drink or a big scoop of ice cream - and are shortly met with excruciating pain.

We're talking the dreaded "brain freeze," - often dubbed an "ice cream headache" - and a new study claims to have finally unlocked clues as to what causes this chilly sensation. The researchers behind the study say their findings may lead to better treatments for other headache sufferers, such as people with migraines or those with traumatic brain injuries.

Almost everyone has felt brain freeze at some point in their lives, according to the study and the effect is triggered by an ice-cold sip of liquid or a slurp of an ice cream or some other chilly product hitting the mouth's upper palate. But scientists have long been unable to explain the phenomenon - until now.

For the study, presented this week at the Experimental Biology 2012 meeting in San Diego, researchers induced brain freeze in 13 healthy adults by having them sip ice cold water with a straw on their upper palate. The researchers monitored participants' blood flow in their brains with a "transcranial Doppler test," and found the sudden headache seems to be triggered by an abrupt increase in blood flow on the brain's anterior cerebral artery. The pain disappears when that artery constricts, an effect researchers reproduced by having participants drink warm water.

According to the researchers, since migraine sufferers are more likely to experience brain freeze than people who don't experience the icy headache often, brain freeze may share traits with other types of headaches, including those brought on by the trauma of blast-related combat injuries in soldiers or migraines. One possible link between brain freeze and other headaches is local changes in brain blood flow. If further research confirms all these types of headaches are caused by blood flow changes, new drugs that block widening of the blood vessels - called vasodilation - could improve treatment for sufferers.

Why does this increase in blood flow occur? The researchers think the brain is adapting to the "freeze" through a self-defense mechanism.

"The brain is one of the relatively important organs in the body, and it needs to be working all the time," study co-author Dr. Jorge Serrador, a cardiovascular electronics researcher at Harvard Medical School in Boston, said in a written statement. "It's fairly sensitive to temperature, so vasodilation might be moving warm blood inside tissue to make sure the brain stays warm." He adds the sudden influx of blood could raise pressure and cause pain.. The blood vessel constriction that follows may be a way to bring pressure down in the brain before it reaches dangerous levels.