Keeping Cool No Help for Head Injury
"I wouldn't say this is the end of hypothermia," Narayan tells WebMD. "But this study clearly shows that the thing is more complicated than one would have hoped. We have similarly not had much luck with [drug] approaches to limiting brain injury. Maybe the way hypothermia was done could be modified in a way that is more effective. It would seem to me that the problem is what helps the brain does not necessarily help the body. So if they can find a way to cool the brain without cooling the entire body, that would be nice -- but that is more easily said than done."
A recent, small-scale trial reported by Cleveland Clinic researcher Derk Krieger, MD, PhD, showed that a very similar hypothermia technique successfully reduces brain damage in stroke patients. Like Clifton, Krieger suggests that the window of opportunity to apply hypothermia to human brain-injury patients may be smaller than previously appreciated.
"The Clifton study may have begun too late in the game," Krieger tells WebMD. He says that there is a difference between brain and body temperature and it is possible the researchers never cooled the brain down sufficiently, which could account for the different results of his team.
Both Krieger and Narayan suggest that smaller brain injuries may be more responsive to hypothermia.
Narayan says that one major positive result of the Clifton et al. study is that it validates the use of a controversial "waived consent" policy. Waived consent allows researchers -- under specifically defined conditions -- to enroll patients in a study without informed consent if the patient is unconscious, not accompanied by family, and might be helped by an experimental intervention that must be given right away if it is to do any good. Hospitals participating in such studies must inform their communities that such a trial is underway -- and must make a bona fide attempt to contact patients' families.
"In the Clifton et al. study, 38% of patients were enrolled with waived consent," Narayan says. "That is a very critical point to bring up, because otherwise research in this area will essentially be strangled. Let's say you have a heart attack and we now have a drug we think will be protective for the brain and will be useful to protect the brain while you are being resuscitated. At that point you aren't going to be trying desperately to find the family -- you want to treat as soon as possible. Of course, these drugs would already have gone through preclinical and [preliminary] safety testing before you come to that. [Death and disability] from severe head injury is so great that we need to try to facilitate research rather than hamper it."