The Miami group has already tried the treatment in 33 people, Levi says, and published data on the first 14 in the journal Neurosurgery in 2010. At that point, 43% of subjects had achieved some movement below the injury area. The scientists are now seeking funding to run a larger trial.
Traumatic brain injury
Doctors know that cooling can reduce swelling of brain tissue and thus compression of brain blood vessels. They wonder if it might also prevent long-term brain damage. The issue is controversial, Dietrich says. "It may or may not work."
In very small trials, hypothermia for traumatic brain injury has looked effective. But larger trials are less convincing. For example, in a study of 108 patients published in February in Lancet Neurology, people who received the treatment fared worse, on average, than those who didn't. Of those who got hypothermia, 40% survived with moderate disability at most. In the uncooled group, the number was 55%.
Dietrich and others suspect that cooling would work but only for certain TBI patients. He thinks the best candidates would be people whose brains are bleeding. The blood fills the skull, squashing blood vessels. This restricts blood flow much like in stroke or cardiac arrest, in which therapeutic hypothermia appears to be effective.
In contrast to full cardiac arrest, during a heart attack only a fraction of the heart's blood supply is blocked. Animal studies on hypothermia treatment have been encouraging, but as of yet there are few data from people.
One small, 20-person study, published in 2010 in the journal Circulation: Cardiovascular Interventions, found that cooling reduced the area of the heart damaged by the attack by 38%.