Hypothermia protects the brain against damage during stroke

March 6, 2012, BioMed Central

Thromboembolic stroke, caused by a blood clot in the brain, results in damage to the parts of the brain starved of oxygen. Breaking up the clot with tissue plasminogen activator (tPA) reduces the amount of damage, however, there is a very short time window when the value of the treatment outweighs the side effects. New research published in BioMed Central's open access journal Experimental & Translational Stroke Medicine shows that, during the first 24 hours after a stroke, mild hypothermia (34C) can reduce the side effects of tPA and potentially increase the window of opportunity for tPA treatment.

When a blood clot blocks off blood flow in the brain (ischemic stroke) the part starved of oxygen quickly begins to die. In order to prevent significant damage tPA must be given to the patient as early as possible after the onset of symptoms - doctors recommend that it must be administered within the first four and a half hours. Delayed treatment also increases the patient's risk of intracerebral hemorrhage and brain swelling (edema).

Mild hyperthermia is known to be neuroprotective and to reduce damage caused by the return of blood flow to an area of the brain starved of by a clot. Researchers from the University of Erlangen, led by Dr Rainer Kollmar, tested whether mild hyperthermia could also prevent damage to the brain due to tPA treatment in rats. After 24 hours they found that, while hypothermia reduced the amount of swelling and damaged tissue in the brain after a stroke, tPA (administered 90 minutes after the onset of stroke) increased it. However, they also discovered that hypothermia therapy was able to offset the damage due to tPA.

This seemed to be true for all the measurements they looked at. Dr Kollmar explained, "Patients often loose brain function such as control over parts of their body, speech or memory after stroke. We looked at 'neuroscore', to examine how much control of the body had been affected, and at markers for inflammation (TIMP-1 and sICAM) or evidence of damage to the blood brain barrier. In all cases hypothermia was able to offset the side effects of tPA."

While these results are still experimental, new techniques which prevent shivering mean that this technique is easier to administer in conscious patients. Preliminary clinical trials are also beginning to show that it is possible to treat patients, who have had a stroke, with tPA plus hypothermia. Our results suggest that hypothermia can offset the side effects of tPA and further studies will show if it is also able to increase the window of opportunity of treatment in patients.

Explore further: New clue to brain bleeding after stroke treatment

More information: Mild hypothermia of 34C reduces side effects of rt-PA treatment after thromboembolic stroke in rats, Bernd Kallmünzer, Stefan Schwab and Rainer Kollmar, Experimental & Translational Stroke Medicine (in press)

Related Stories

New clue to brain bleeding after stroke treatment

October 17, 2011
The only medication currently approved for stroke treatment – tissue plasminogen activator (tPA), which dissolves blood clots – is associated with an increased risk of bleeding in the brain, particularly among patients ...

Use of clot busters for stroke increased from 2005 to 2009, but still low

June 2, 2011
The use of clot-busting drugs to treat acute ischemic stroke increased from 2005 through 2009 — but is still low, according to research reported in Stroke: Journal of the American Heart Association.

Recommended for you

To sleep, perchance to forget

February 17, 2018
The debate in sleep science has gone on for a generation. People and other animals sicken and die if they are deprived of sleep, but why is sleep so essential?

Newborn babies who suffered stroke regain language function in opposite side of brain

February 17, 2018
It's not rare that a baby experiences a stroke around the time it is born. Birth is hard on the brain, as is the change in blood circulation from the mother to the neonate. At least 1 in 4,000 babies are affected shortly ...

Lab-grown human cerebellar cells yield clues to autism

February 16, 2018
Increasing evidence has linked autism spectrum disorder (ASD) with dysfunction of the brain's cerebellum, but the details have been unclear. In a new study, researchers at Boston Children's Hospital used stem cell technology ...

Fragile X syndrome neurons can be restored, study shows

February 16, 2018
Fragile X syndrome is the most frequent cause of intellectual disability in males, affecting one out of every 3,600 boys born. The syndrome can also cause autistic traits, such as social and communication deficits, as well ...

Brain-machine interface study suggests how brains prepare for action

February 16, 2018
Somewhere right now in Pyeongchang, South Korea, an Olympic skier is thinking through the twists and spins she'll make in the aerial competition, a speed skater is visualizing how he'll sneak past a competitor on the inside ...

Humans blink strategically in response to environmental demands

February 16, 2018
If a brief event in our surroundings is about to happen, it is probably better not to blink during that moment. A team of researchers at the Centre for Cognitive Science from Technische Universität Darmstadt published a ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.