Mechanism behind 'brain freeze' may shed light on migraine cause

Everyone is familiar with the sudden headache induced by greedily eating something frozen and delicious, but the underlying source of this so-called “brain freeze” has always eluded scientific understanding.  Recently, however, scientists presented a study at the Experimental Biology annual meeting in San Diego proposing a probable answer for this mysterious phenomenon. 

The method for unearthing these findings required monitoring seventeen subjects’ brains via transcranial Doppler while they sipped frigid water through a straw, voluntarily subjecting themselves to brain freeze. This monitoring system allowed researchers to observe changes in arterial blood flow when the subjects alerted them to an oncoming freeze.  The results indicated that, just before brain freeze, the anterior cerebral artery opened wider and pumped extra blood to the frontal lobe of the brain, possibly to keep the brain from getting too cold.  As the vessel contracted back to its normal diameter, the pain subsided. 

The researchers behind this project, members of the Department of Veterans Affairs New Jersey Health Care System, suggested that the pain felt during brain freeze may stem from the excess pressure generated by this sudden influx of blood to the frontal lobe. This hypothesis may in turn lead to a better understanding of something significantly less comfortable than the brief ache experienced after eating a novelty dessert: a migraine. 

Roughly 30 million Americans suffer from migraine headaches, which are known to induce debilitating pain, and can last anywhere from four to seventy-two hours.  Migraine sufferers report throbbing or pulsating pain on one side of the head, blurred vision, sensitivity to light and sound, nausea and vomiting.  Despite such high incidence rates and severe symptoms, little is understood about the underlying causes of migraines.  Several factors have been identified that may increase an individual’s chance of having migraines, including family history, age, gender (women are more likely than men to suffer from migraines), certain medical conditions (depression, anxiety, stroke, epilepsy and high blood pressure are all associated with migraines) and hormonal changes.  Still, the exact cause is not fully understood. 

With this new brain freeze study, however, scientists may have a clue to unlocking the mystery surrounding these powerful headaches.  Some researchers believe that migraines occur when there is abnormal inflammation in the brain that causes blood vessels to swell and press on nerves, resulting in pain and the other side effects experienced by migraine sufferers.  This belief is in keeping with the mechanism behind brain freeze, which similarly dilates blood vessels in the frontal lobe. 

Despite a limited understanding of its causes, doctors have sought migraine treatments, most recently in the form of Botox injections.  When treating migraines, specialists administer thirty-one Botox injections into seven specific head and neck sites; the treatment is expected to produce results lasting up to three months.  This treatment was first proposed when it was observed that patients with chronic headaches receiving cosmetic Botox injections experienced headache improvement, prompting case studies that suggested benefit.  Yet, the medical literature on Botox effectiveness for treating headaches has been mixed. 

Botox works by binding to receptor sites on the nerve terminals, blocking the release of acetylcholine, a neurotransmitter that results in pain.  It thereby curbs headache pain by blocking the sensory nerves that relay pain messages to the brain.  But this appears to be no better than utilizing any other painkiller -- it acts merely as a Band-Aid, rather than addressing the underlying causes of the pain.  Hopefully a better understanding of the blood vessel-based mechanisms underlying migraines will allow scientists to develop treatments that target these causes, rather than simply masking the symptoms.