I was sitting here like the nerd I am, not thinking of the
UofA basketball team or attractive ladies walking by, but of how to slow
ischemic stroke and decrease the stroke infarct volume. A very simple idea
popped into my head: hypothermia! What
do you do when you break your leg and it swells? You put ice on it! Why not do
that to the brain?
It is also already known that many who suffer heart attacks
or drowning in cold water have a much higher chance of survival than at non-hypothermic
conditions. So I started my research and was actually very surprised to
actually see people are studying/testing this. I had no idea this was an actual
concept! **Victory dance that I actually had a good idea! <('
One group studied two ways of cooling; surface cooling and endovascular
cooling. Intravascular cooling is being studied now and is not included in this
article. Both trials (surface and endovascular) results show the feasibility of
the concept but cannot comment on the safety of the procedure.
Models of temporary ischemia with administration of
hypothermia show a reduction in infarct size and improvement in behavioral
outcomes.They show that hypothermia initiated after 5 minutes of ischemic
stroke onset protected the cortical ad hippocamplan neurons. However,
hypothermia was not effective when initiated 30 minutes after. This is much
different in animal studies. Both 2 and 6 hour delays show protective effects.
A 22 hour delay showed to be even more neuroprotective.
They hypothesize that the mode of protection comes from the
fact that it causes metabolic rate of the brain to slow as well as reduces release
of inflammation markers and free radicals. I would imagine it would also help
with reperfusion injury as well once the embolism is removed.
Surface cooling can use air blankets, water mattresses,
alcohol bathing, cooling jackets, and ice packing. Advantages are its
simplicity and ability to even be performed at home, in a crude way, while
waiting for the ambulance. However, this takes several hours to reach the
desired temperature.
Endovascular cooling uses catheters that can be inserted
directly into the central venous system transferring heat via transduction
through an internal circulation in the catheter. This is much quicker, tighter
temperature control and reduces shivering quite a bit.
With either case passive re-warming is used afterwards.
These therapies could be combined with neuroprotective agents to augment each
other.
http://stroke.ahajournals.org/content/38/2/794.long
I think this is a really cool concept! For me personally, I know I like using cool packs for my forehead when I have a migraine, so I applaud Tim for looking into this for strokes. I like that both surface and more invasive procedures are discussed, because both really would have their advantages depending on the circumstance.I would like to see more studies done on whether cool temperatures really reduce the release of inflammation and free radical markers.
ReplyDeleteWhat other tests would you wish to have? We test the effect of cool temperatures on inflammation every day. When something swells up what do you put on it? I don't think its a question of if cool temperatures actually work but at what temperature works best and what side effects could occur.
ReplyDeleteThis is really interesting! It makes me wonder what else cooling could control. We've been talking about all the ties between inflammation and various disease states for the whole semester. The article states that a study by Wang et al found that 2 hours of hypothermia showed reduction of inflammation up to 1 week later. So, do you guys think that this could be used as a treatment for the other disease states we've talked about in class? Could once a week hypothermia treatment be beneficial? Of course, we'd have to figure out the side effects of long term treatment--I'm guessing we could see suppression of the immune system with regular treatment leading to susceptibility to viral and bacterial infection, but what else? Would the benefits outweigh the side effects? It would definitely be interesting to see!
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