Stroke care happens to be very near and dear to my heart and was the initial reason that I sought a career in EMS. Watching a person have a stroke or CVA (cerebral vascular accident), has to be one of the worst experiences. These patient's are very likely going to live a very difficult life after having a stroke. Unfortunately, there is very little that we can do in the prehospital environment for these patients.
There are two main types of strokes. A "clot" or a "bleed".
A clot refers to what is known as an ischemic stroke. This occurs due to an occlusion of a cerebral artery by a thrombus or embolus--a clot. The portion of the brain distal to or after the occlusion becomes hypoxic or ischemic. This means that there is very little or no oxygen reaching the tissues of the brain. This will cause a compromise to whatever part of the body is controlled by this ischemic brain tissue. Ischemic strokes are generally less lethal, and have a better response to treatment, if performed early enough.
A bleed refers to what is clinically known as a hemorrhagic stroke. As it's nickname implies, a bleed involves bleeding. Usually pre-cursed by hypertension, an aneurism or weakening of a cerebral artery is formed and then ruptured. This causes ischemia distal to the rupture. In addition, a build up of intracranial pressure may occur. This may lead to further compromise by way of herniation. If the brainstem herniates, airway and circulatory compromise are likely to follow. These types of strokes have a higher rate of mortality and worse morbidity.
Note: A transient ischemic attack or TIA is what is known as a "mini stroke", and is caused by a temporary blockage, resulting in temporary symptoms of stroke. Frequent TIAs increase the likelihood off an ischemic stroke. If you are unsure if the patient is having a TIA, treat as a stroke.
Treatment
Currently, CVA treatment is surrounded around early recognition and rapid transport. The most common treatments to improve patient outcomes are specific to ischemic strokes. There is a three hour time window for thrombolytic therapy and a large list of contraindications that go with it. There is a five hour time window for comprehensive stroke care. Neuro-surgeons can actually go in and retrieve the clot from an occluded artery. These time windows give EMS personnel a very important job. Recognize the symptoms and transport.
Symptoms of stroke
There are so many possible symptoms of stroke, and only few are highly specific to an actual CVA. The hospitals use an additional number of references to make their decisions.
Cincinnati Stroke Scale:
- Facial droop
- Arm drift
- Slurred speech
Magnesium has been under clinical trials for sometime now as a neuroprotective agent. Check out this link: Fast-MAG
Induced Hypothermia - NEED MORE RESEARCH. There is some very promising stuff out there, and it only makes sense that if hypothermia works for the post-arrest hypoxic brain, why not the stroke brain?
Below is from Critical Care Medicine, published in 2009.
Below is from Critical Care Medicine, published in 2009.
Abstract
Hypothermia is considered nature's "gold standard" for neuroprotection, and its efficacy for improving outcome in patients with hypoxic-ischemic brain injury as a result of cardiac arrest is well-established. Hypothermia reduces brain edema and intracranial pressure in patients with traumatic brain injury. By contrast, only a few small pilot studies have evaluated hypothermia as a treatment for acute ischemic stroke, and no controlled trials of hypothermia for hemorrhagic stroke have been performed. Logistic challenges present an important barrier to the widespread application of hypothermia for stroke, most importantly the need for high-quality critical care to start immediately in the emergency department. Rapid induction of hypothermia within 3 to 6 hrs of onset has been hampered by slow cooling rates, but is feasible. Delayed cooling for the treatment of cytotoxic brain edema does not provide definitive or lasting treatment for intracranial mass effect, and should not be used as an alternative to hemicraniectomy. Sustained fever control is feasible in patients with intracerebral and subarachnoid hemorrhage, but has yet to be tested in a phase III study. Important observations from studies investigating the use of hypothermia for stroke to date include the necessity for proactive antishivering therapy for successful cooling, the importance of slow controlled rewarming to avoid rebound brain edema, and the high risk for infectious and cardiovascular complications in this patient population. More research is clearly needed to bring us closer to the successful application of hypothermia in the treatment for stroke.
3 comments:
Interestingly our regional stroke centre is now using a 4-5hr window for thrmbolytic therapy and I'm told that our criteria are going to be adjusted accordingly here eventually.
That is interesting. Are you sure it isn't for comprehensive stroke Tx?
Here is a quick article about tPA up to 4.5 hours. I read something about it a few months ago, but I honestly don't remember all the specifics.
On a side note, I wonder if anything will change regarding FAST-MAG. We currently have a two hour symptom onset window to enroll a patient in the study. From what I understand, the trial has just over half of the number of patients we need to enroll in the study. Probably can't change now because of the study rules though.
Keep up the great work. Thanks for the information.
http://www.medscape.com/viewarticle/707660
http://stroke.ahajournals.org/cgi/content/full/40/8/2945
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