Chill May Help Stroke Victims
B O S T O N, Aug. 31, 2000 -- “In cold blood” may have new meaning for stroke victims.
A team of Danish researchers says lowering the body temperature by 1 degree Celsius has helped a small group of stroke sufferers survive and has lessened their development of brain damage.
The study of 17 people is being reported in the current issue of the American Heart Association’s journal Stroke.
Doctors at the Bispebjerg Hospital in Copenhagen treated patients who had moderate strokes by lowering their body temperature within 12 hours of the event.
Compared with patients who’d had standard stroke treatment, the patients who were chilled with a cooling blanket were nearly twice as likely to survive six months later and had less brain damage, the researchers found.
Stroke occurs when the blood — and therefore, oxygen — supply to the brain is cut off, either by a blood vessel suddenly clotting or bursting open as in a hemorrhage.
As a result, brain tissue becomes damaged or dies, affecting speech and motor capabilities. Treatment of stroke patients can include immediately administering a drug called t-PA or other anti-clotting medicines to clear a clogged blood vessel, or surgical intervention when necessary.
Icy Waters Ahead
Researchers are not yet sure why lowering the temperature seems to reduce neuronal damage.
“We have known that lowering the temperature does slow brain metabolism, and can protect the brain in an acute [stroke] event,” says Harold Adams, a professor of neurology at the University of Iowa in Iowa City, commenting on the study. “You’ve heard stories about children falling in icy water during the winter and being resuscitated after a prolonged period. The presumption is that the hypothermia was protective.”
But experts caution the Danish work is preliminary and only involved a small sample of patients with mild stroke. Questions still needing resolution include which patients would benefit from the treatment, what temperature is ideal and how quickly should the body temperature be lowered.
The National Institutes of Health has been studying the effects of lowering body temperature on animals with stroke, and it is already investigating how lowering the body temperature may work in other brain maladies.
Researchers began a study four months ago looking at the effects of cooling patients during operations to remove brain aneurysms, a ballooning of a blood vessel that can cause a stroke if it bursts.
“The idea that cooling people has some benefits in terms of protecting the brain is an old idea,” says Dr. Michael Todd, a professor of anesthesia at the University of Iowa who is leading the NIH study. “What’s of interest now is whether cooling people just a little is helpful.”
“Given the consistent and significant effects of hypothermia in animal models, [this] should be one of the next major frontiers in stroke therapy,” predicts Dr. Steven Levine, neurology professor at Wayne State University in Detroit.
Chilling a Hot Topic Dr. Camilo Gomez, a neurologist at the University of Alabama at Birmingham, has aggressively used body-temperature lowering on 20 stroke victims in the past few years, bringing their body temperature down to 33 degrees Celsius (91 degrees Fahrenheit) — well below normal range of 36 to 37.
“This is one of the hottest topics in our field,” Gomez says.
Dr. Derk Krieger, a neurologist at the Cleveland Clinic in Ohio, has just completed a pilot study in which he lowered the body temperature of 10 patients with acute stroke to help facilitate brain surgery. He compared these patients to stroke victims who had the standard surgery.
With promising early results from the study — called COOLAID, from Cooling for Acute Ischemic Brain Damage — Krieger and around 10 research centers across the United States have applied to the NIH for grants to study stroke victims.
Although the Danish study is limited in size and scope and only found limited improvement, Krieger says: “This moves stroke in the right direction. We are on a wave, and everybody is interested in this.”