Doctors at Children's Hospital Los Angeles have pinpointed why an unusual treatment - hypothermia - works to protect newborn brains from damage.

The technique involves targeting the infant's brain with cool temperatures, which induces hypothermia, or excessively low body temperature. You may have heard of hypothermia in the context of someone walking for miles in the snow, or being lost at sea. The body loses heat faster than it can produce it, slowing down the heart and depriving vital organs of needed blood and oxygen. The sufferer slowly dies, if they don't get warmed up. But in one condition common in newborns, hypothermia can be life-saving, and is actually the first step in preventing brain damage.

Hypoxic-ischemic encephalopathy, a disorder in which a newborn's brain doesn't get enough oxygen, affects about 1.5 in every 1,000 infants. HIE, as it is better known, is a leading cause of death in infants. It also is a common cause of disabilities like cerebral palsy, epilepsy, blindness, severe hearing impairment, motor movement issues, and cognitive developmental delays. Around a quarter of infants with HIE die in the hospital. The survivors may seem healthy and able-bodied immediately following birth, but eventually exhibit symptoms of disability, as it takes days or weeks for the disorder's progress to finish.

With doctor-induced hypothermia, though, doctors see almost double the rate of recovery. Why exactly it works has been a mystery.

"Although we know hypothermia helps, we don't fully understand how it helps or how best to help those babies for whom hypothermia isn't enough to alleviate their brain injury," said Jessica Wisnowski, Ph.D., of the Department of Radiology at Children's Hospital Los Angeles, in a press release. 

It's counterintuitive that hypothermia would help a growing brain. After all, when someone develops hypothermia in nature, their body is slowing down and is extremely vulnerable to injury. Yet, in HIE, hypothermia seems to prevent further injury.

If doctors can figure out what exactly hypothermia does to slow or stop brain damage, they could tweak their treatments to possibly help more children. So, the researchers at Children's Hospital Los Angeles had an idea: They would move all of the equipment from the infant critical care unit to the MRS lab, where magnetic imagery is used to spot what the brain is doing. (MRS machines are different from MRI machines in that they spot metabolic activity rather than giving a "cross section" of the brain.)

The doctors were able to see the infants' brains up close during and after the therapy, and determine that the hypothermia-treated brains were able to restore a particular balance between making energy for the brain cells to survive (basically, brain food) and making neurotransmitters, which are the brain's method of talking to the rest of the body (basically, brain phone lines). 

If the brain fails to achieve proper balance between these two things, something will suffer, whether it's getting the brain food, or giving it the tools to talk to the rest of the body. It's no wonder, then, that a disability could result.

The findings were published this week in the Journal of Cerebral Blood Flow and Metabolism.