Inducing Brain Freeze Reveals Possible Cause of Headaches
The study of the causes of many types of headaches is an elusive mystery for researchers. Part of the problem is that researchers have had to rely on headache-causing drugs and patients with chronic headaches for their research—both of which present practical experimental complications. To compensate for these shortcomings, researchers have turned to inducing brain freeze in volunteers by drinking both warm and cold drinks while undergoing Transcranial Doppler (TCD) analysis.
A Transcranial Doppler is used to measure the velocity of blood flow through the vessels of the brain. It works by emitting a high-pitched ultrasound wave from a probe that upon contact with a blood vessel bounces off and back to the probe with a change in frequency from bouncing off the blood vessel. It is the velocity of the blood flowing through a vessel that actually affects the ultrasound wave frequency as it returns to the probe. The change in frequencies is what is detected and then used in calculating the speed of the flow of blood through a vein or artery. TCD is primarily a technique for measuring relative changes in blood flow.
The importance of technology such as TCD is that it provides answers to questions surrounding causes of headaches that range from the common brain freeze pain experienced from drinking an icy drink too fast, to understanding brain injury in soldiers that have experienced shockwave trauma to the head from an exploding IED. By being able to induce headaches naturally and on command while analyzed with a Transcranial Doppler, researchers are able to take a look at what is going on in the brain that may link brain freeze pain with cerebral injury and/or other types of pain such as migraine headaches.
A recent study titled “Cerebral Vascular Blood Flow Changes During ‘Brain Freeze,’” was recently presented at a scientific conference—Experimental Biology 2012—being held at the San Diego Convention Center.
The study is a multi-partner governmental and academic collaboration to assess what physiological changes might prompt headaches. In this particular study, 13 healthy adult volunteers were asked to first sip ice water with a straw pressed against their upper palate (the ideal condition for inducing a brain freeze) followed by sipping the same amount of room temperature water. The sipping acts were performed while the blood vessels to their brains were analyzed with a Transcranial Doppler. The volunteers would hand signal when pain began and when pain ended during the water sipping.
What the researchers found was that one particular artery—the anterior cerebral artery—dilated rapidly and flooded the brain with blood during the same time the volunteers experienced pain. Soon after this dilation occurred, the same vessel constricted as the volunteers’ pain faded away.
The researchers believe that the relatively rapid dilation/constriction response of the anterior cerebral artery may be a way that the brain protects itself from sudden changes in arterial blood pressure and that the response induces pain in the process.
According to a press release by the American Physiological Society, one of the researchers of the study, Jorge Serrador of Harvard Medical School, states that “The brain is one of the relatively important organs in the body, and it needs to be working all the time,” he explains. “It’s fairly sensitive to temperature, so vasodilation might be moving warm blood inside tissue to make sure the brain stays warm.” But because the skull is a closed structure, Serrador adds, the sudden influx of blood could raise pressure and induce pain. The following vasoconstriction may be a way to bring pressure down in the brain before it reaches dangerous levels.
The researchers note that their findings might also explain the cause of other types of headaches as being related to changes in blood flow in the brain’s blood vessels. This in turn opens the possibility of future drugs being developed that could block sudden vasodilation and thereby offer patients with chronic migraine headaches an effective therapy for preventing their headache pain.
Image Source: Courtesy of Wikipedia
Reference: American Physiological Society press release