Thrombolysis for stroke- sooner the better!!!
Nitin K.Sethi, MD
A new study on treatment of stroke was published this week in the New England Journal of Medicine (NEJM). The study concerns thrombolytic therapy for stroke and since I feel very strongly about stroke prevention and treatment, I thought I would share the relevant details with my readers. The study “Thrombolysis with Alteplase 3 to 4.5 hours after acute ischemic stroke” and the accompanying editorial by Dr. Lyden appears in the Sep 25th issue of NEJM.
Ischemic stroke (stroke due to lack of blood flow to the brain) can be devastating leaving survivors with neurological deficits (paralysed on one half of the body, unable to walk or talk). When a patient lands up in the ER with an acute ischemic stroke (I like to refer to it as “brain attack” kind of similar to “heart attack” which patients and family members find easier to understand), as doctors we try hard to salvage the brain tissue at risk of “death”. One of the main drugs in our armament in this fight is a drug called tPA (Tissue plasminogen activator). tPA acts like a clot buster (the drug lyses/ bursts the clot in the brain and helps to reestablish blood flow).
Let me try to explain this in a more simple way. A blood clot breaks from the heart and travels up to the brain, there it lodges in a small blood vessel of the brain preventing blood flow distally (beyond the clot). Patient presents with left arm and leg weakness to the hospital. The brain tissue supplied by the blocked blood vessel now gets no blood and starts to die. “A STROKE IN EVOLUTION” . If blood flow is not reestablished soon, the brain tissue suffers irreversible necrosis and death. This patient is given tPA, the drug lyses/ bursts the clot and helps to reestablish blood flow. The patient who was weak on one side starts moving his arm and leg again.
It is not as simple as I made it out to be above. Patients have to meet strict inclusion criteria before tPA can be administered. Also the drug has a window period and has to be given intravenously within 3 hours of the stroke starting. 3 HOURS THAT IS THE GOLDEN PERIOD. Patients presenting to the ER after 3 hours are usually denied tPA for 2 main reasons-one the tissue which was at risk for stroke is now irreversibly destroyed and thus cannot be salvaged and second the risk for intracranial hemorrhage (bleeding inside the brain) is high.
The study reported in NEJM extends this window period (golden period) from 3 to now 4 and half hours. You can now understang why this study is generating so much interests among doctors and neurologists in particular. Patients presenting to the hospital upto 4 and half hours after an ischemic stroke can be given tPA provided they meet the other inclusion criteria (and none of the exclusion criteria).
But as Dr. Lyden in his editorial rightly points out, this should not be taken to mean that now you have more time to wait before going to the hospital to seek help (or for us doctors as more time to wait before we decide to administer tPA). When it comes to stroke, TIME IS BRAIN. The more you wait, the more brain tissue is lost, the more brain cells die, the more disability the patient is left behind with.
It is extremely important that the public learn to recognize the early warning signs of stroke and seek help as soon as possible. You can read more about the early warning signs of stroke either on my blog here or on my website http://braindiseases.info.