Transcript
WEBVTT
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G'Day did you realize that Hippocrates first described the sudden paralysis associated with stroke?
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And then in 2020, there was an estimated 39,000 stroke events in Australia, more than a hundred every day.
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With the incidence of stroke increasing from the age of 30 and their various causes of stroke varying, depending upon the age of the patient.
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Today, we're going to learn more about it.
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In the previous episode we spoke to Ewan(Puggy) and Liz about Puggy's stroke.
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And we heard about his intimate journey from their stroke to the a long road of recovery.
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Today we will dive into the diagnosis treatment and then the intricacies of cerebrovascular events to provide a comprehensive outline and treatment for these serious events.
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G'day and welcome to Aussie Med Ed, the Australian medical education podcast, designed with a pragmatic approach to medical conditions by interviewing specialists in the medical field.
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I'm Gavin Nimon an orthopaedic surgeon, and I'm based in Adelaide, and I'm broadcasting from Kaurna land I'd like to remind you that if you enjoy this podcast, please subscribe or leave a review or give us a thumbs up as I really appreciate the support and it helps the channel grow It's my pleasure now to introduce Dr.
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Michael Waters, an interventional neurologist who works at the Royal Adelaide Hospital following neurology training, he undertook a further three fellowship years, in interventional neuroradiology, both in Australia and in the United States.
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He works as a stroke neurologist and neurointerventionist, providing minimally invasive endovascular treatment for stroke, cerebral aneurysms and other neurovascular diseases.
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Welcome Michael!
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Michael, thank you very much for coming on Aussie Med Ed.
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No worries, good to be here.
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I'd like to, first of all, you've heard the story of Puggy, a friend of mine and his stroke.
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How would you actually define a stroke and how common are they that occur in Australia and around the world?
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Yeah, so I guess traditionally strokes were called cerebrovascular accidents or CVA's.
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And that naming changed in recent times because I guess we realized that they weren't really accidents anymore.
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We usually had a clear cause for them.
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And so now they're just termed generally a stroke and that covers both ischemic and hemorrhagic.
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So basically a stroke is damage to the brain due to a problem with the blood vessels.
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And the problem with the blood vessels can be a blocked blood vessel, which would be an ischemic stroke or a burst blood vessel, which is a hemorrhagic stroke, bleeding of the blood vessels.
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So that's the general classification.
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They're quite common.
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In Australia about 5%.
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The prevalence of stroke is about 5 percent in the over 65 age group.
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As you get to over 85, the prevalence is about 15%.
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So that's quite common.
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And in Australia, about 85 % of those strokes are ischaemic.
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And about 15% of hemorrhagic and that, changes as you go around the world and even within Australia.
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So Indigenous and First Nations people in Australia have a much higher incidence of stroke and prevalence of stroke, and especially hemorrhagic stroke.
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They're o overrepresented in that category.
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And then in certain parts around the world, the incidents and prevalence will be different as well.
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For example, subarachnoid hemorrhage, a type of hemorrhagic stroke.
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It's much more common in Japanese and Finnish people.
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Hemorrhagic stroke is more common in certain ethnic groups, including Chinese.
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And then also different types of ischemic strokes are more prevalent in different populations as well.
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For example, intracranial atherosclerosis as the cause of a stroke is quite common as a stroke subtype in the Chinese especially Han Chinese population.
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So it does vary as you go around the globe globally, about two thirds of stroke ischemic and about one-third is hemorrhagic which is slightly different from the numbers in Australia where the even higher proportion are ischemic.
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Okay, and where does transient ischemic attacks or TIAs fit into this picture?
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Are they mini strokes that just don't give a significant effect or are they just minor small blips in the actual function of the brain for short term function.
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Yeah, a mini stroke is a reasonable way to classify them, but they're really different by definition and by time course only.
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So a TIA by its definition is transient ischemia, which lasts less than 24 hours or without a signature of infarction on the MRI.
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So we're picking up a lot more strokes these days because MRI is so much more readily available.
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So symptoms that may have only lasted 15, 20 minutes and would previously be classified as a TIA is now leaving its stamp basically on an MRI so we can classify that as a stroke because it has been damaged to the brain tissue.
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But really, they can be as serious as each other, both deserve the workup to find the cause to prevent, further stroke or TIA.
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But yeah, really the same sort of pathological process, but different only by time course.
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So really in the past when I learned that TIA was a minor event that was actually a prelude to a stroke, really with better imaging and as the imaging improves with years to come, we actually realise that all of these are strokes and just as bad as each other.
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Yeah, certainly we need to take TIAs seriously because it can herald a larger stroke.
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People with firstly, new diagnosis of atrial fibrillation or atherosclerosis in the neck, which might present initially with just transient symptoms.
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they might be at very high risk of having a large stroke.
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So these are the patients that you definitely want to pick up.
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TIA can be tricky because, for example, most patients that come through a TIA clinic in the hospital pathway, the majority of those won't actually be a true TIA or ischemia.
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There's often stroke mimics such as migraine and Other causes of vertigo such as peripheral vertigo and these sort of stuff.
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So there's lots of stroke mimics but if it is a true TIA, then yeah, definitely deserves the respect that, true ischemia would deserve because it can be a herald to something more serious.
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Okay.
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You've mentioned the actual difference in the actual incidence depending on the population.
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What other risk factors are there as well?
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And, actually one thought when we are talking about the different incidences, does collagen deficiencies influence the risk of hemorrhagic type strokes as well.
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Is that a factor too?
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Yeah, so there's a lot of risk factors.
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In general terms, the risk factors for cardiovascular disease very similar to the risk factors for cerebrovascular disease.
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The major cerebrovascular risk factors are the classic ones such as hypertension, hyperlipidemia, diabetes smoking, obesity, and then things like Alcoholism are also risk factors, renal failure, so they're the sort of, the classic ones that encompass the whole cardiovascular, cerebrovascular risk factors, and then there's more specific risk factors for certain types of strokes, so yes, collagen deficiency diseases can be risk factor for hemorrhagic stroke, for subarachnoid hemorrhage but also for vessel dissection, and vessel dissection can lead to to ischemic stroke, and then you've got your cardioembolic strokes as well and specifically looking at things like atrial fibrillation, which is the most the most common cause of a cardioembolic stroke.
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Okay.
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when you think of the actual risk factors, in the cardiac history, we use the Chadsvasc score to assess whether there's a risk of a cardiac event occurring.
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Is the CHADVAS score used in cerebral vascular accidents as well, or is it another type of score that's used?
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We, we don't specifically use Chadsvasc, although we use that for patients obviously with atrial fibrillation.
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We have other scores such as ABCD2 score, which looks at things like age, blood pressure and diabetes and previous stroke symptoms.
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There are scores that we use to classify an overall risk in someone with a TIA.
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And then a lot of the risk as well will depend on the imaging, which we do and the other tests that we do.
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For someone with a stroke, or stroke like symptoms, the key early investigations are a CT scan, and a CT angiogram, which gives us the parenchyma the tissue of the brain but also the vessels, the heart and the veins, the highways in and out.
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And that enables us to stratify risk quite early in an emergency setting by knowing what the vessels are looking like and knowing what the brain parenchyma looks like.
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So that's probably the most important early test to work out what's going on.
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So a CT angiogram as opposed to something like an MRI angiogram.
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Is that because a CT is a quicker investigation or is it just more easily available?
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Yeah, it's also a better investigation for blood vessels.
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It's much more readily available.
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In some countries such as France, then they often triage their stroke patients with MRI because it seems to be readily available in the big cities.
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But for us, yeah, the CT angiogram,, gives excellent vessels, luminal vessels, of what's going inside the blood vessel.
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If there's stenosis, if there's any thrombosis associated with that.
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And so that gives us everything we need.
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And then usually we'll do an mri, down the track to confirm.
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The MRI gives much better views of the actual parenchyma or the brain tissue whereas the blood vessels are well captured on a CT scan.
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In looking at a stroke, or someone who presents with acute stroke symptoms.
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To compare it to cardiac disease and our fields evolving in an interventional sense about 25 or 30 years interventional cardiologists.
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And so the direct comparison for a, for an ischemic stroke brain emergency is that heart emergency of the STEMI.
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So patient comes in with chest pain, and you want to see if the patient has a coronary vessel blockage or a STEMI.
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So similarly a patient comes in with.
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Neurological symptoms, so our chest pain is the neurological symptoms.
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Then the best first test, their best test would be the ECG to confirm the STEMI.
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Our best test to confirm the vessel occlusion for an ischemic stroke is is the CT angiogram.
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And then...
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Basically, then we can find the patients who are candidates for urgent reperfusion.
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Because we've also learned from our cardiology colleagues that, opening the blood vessel gives the patient the best outcome in the heart and in the brain.
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And so that sort of, urgent workup of the CT and the CT angiogram shows us which patients will benefit acutely from reperfusion and revascularization.
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Which gives them the best chance of a good outcome.
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And that's it for ischemic stroke specifically.
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yeah.
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So do you do a CT scan to assess whether there's a ischemic before or a hemorrhagic before you do the CT angiogram or do you just go straight to the CT angiogram
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We do.
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Yeah, you can, we go straight.
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So CT and CT angiogram.
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So CT gives us a lot of information.
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So CT, a plain CT scan will pick up hemorrhage and that'll be parenchymal hemorrhage or subarachnoid hemorrhage.
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So the different subtypes of hemorrhagic stroke.
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It'll show us in an ischemic stroke if the brain is already dead.
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If it's too far gone or if reperfusing the blocked blood vessel would be futile.
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So it shows us that as well.
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So the plain brain gives us a lot of information and then the CT angiogram shows us exactly what's going on with the vessels we're looking for an acute blockage which might be able to be reperfused, either through thrombectomy or through thrombolysis, we can.
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Probably talk about that in a bit, but also it's helpful for hemorrhagic stroke because hemorrhagic strokes can be due to aneurysm or subarachnoid hemorrhage, which can be due to obviously a cerebral aneurysm, which will be picked up usually on the CTA, arteriovenous malformations and other causes of intracranial hemorrhage will as well.
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We'll get a clue to those on the CTA.
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Some of those patients might require formal angiography, catheter angiography.
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But the CTA is a fantastic screening test for us to know what's going on with the vessels.
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And as well, more recently we're doing something called CT perfusion imaging, which basically shows us the area of thread and brain and shows us this key concept of what is the penumbra.
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So the penumbra is the salvageable tissue of the brain, which can be salvaged in an ischemic stroke if the blood vessels reopened.
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and so the CT perfusion imaging will show us that and show us which candidates will, which patients might benefit from acute reperfusion therapies.
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well take a step back, obviously a patient who we suspect is having a stroke, the most common symptoms you will see that they come in with, what would they be?
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And also how important is it to get to the hospital as quickly as possible?
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Yeah, it's very important.
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In a similar fashion, comparing to cardiology, we've learned a lot from our cardiology colleagues, not just in techniques and treatment and how to reperfuse, but also, educating the community about symptoms and how urgent symptoms are.
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So cardiology have done that very well with heart attacks and chest pain.
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And now there's, mnemonics and other catchy phrases to, try and identify or try and let the community know what the symptoms are of stroke.
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One is fast or be fast.
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So that'll cover a lot of the stroke symptoms.
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So B for balance, E for eyes or vision, F for facial droop, A for arm.
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S for Speech Disturbance, and T just for Time.
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BeFast, and the T showing the importance of time and getting to hospital urgently, so that you can be in a window for therapies.
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That covers most.
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Most of the big sort of symptoms of ischemic stroke of stroke, both hemorrhagic and ischemic, the problem is that brain is a very complex organ.
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And a stroke can affect any area of the brain.
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And so sometimes the signs or the symptoms of the stroke can be much more subtle.
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If you've got an isolated infarct in the hippocampus, you might just present with amnesia.
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If you've got a very small infarct around the thalamus or sensory cortex, it might just present with With some tingling or numbness on one side, so often the symptoms are more subtle, but the, a BeFAST type mnemonic covers, covers a lot of the symptoms that might indicate a larger stroke or one that would benefit from urgent reperfusion therapies.
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now obviously different areas will have different protocols, but in the Royal Adelaide Hospital, once a patient hits casualty and the A& E doctor appreciates that there could be a stroke occurring.
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What are the steps that they undertake?
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Do they undertake an ECG routinely to see for atrial fibrillation?
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Do we do bloods to look for coagulation profiles, etc.?
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What are the main investigations you'd want?
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Yeah, they do and it's a very coordinated effort when someone comes in as a stroke.
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So there's coordination between emergency and the EMS, the ambulance and the paramedics communicating with Ed initially and communicating with the code stroke team at the hospital.
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So there'll be some pre notification and so the team at the larger hospital can plan for them coming in and plan to get them straight through to the scan.
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So when they come in, yes, so they might already have a rhythm strip of the ECG from the ambulance.
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We will get a 12 lead ECG.
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in the emergency as well.
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But the most important thing is getting into the scanner to get the imaging.
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Because as you just mentioned before, time is very important.
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And time is brain is the, the phrase that's been used a lot in stroke.
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And that's because the acute therapies are time dependent, and the earlier you can deliver those acute therapies, then potentially the best outcome.
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So when they come into the ED there'll be a lot happening at once.
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There'll be brief history, there'll be IV access, there'll be an E C G.
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We'll make sure that there's a patent airway and that the patient's hemodynamically stable.
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And if that's the case, then they'll go straight on the ambulance stretcher into the CT scanner when they're in the CT scanner.
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Staff will be collecting some collateral information, time of onset, any anti coagulants and these sort of things that the patients might be on that might affect the treatment.
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and then as soon as we've got imaging, then we're making a decision about acute treatment.
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And that will depend on whether we're finding a ischemic stroke or hemorrhagic stroke.
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right.
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So ischemic head strokes are the more common ones.
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It's not the puggy scenario, but we'll talk about ischemic first of all.
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We've already talked about the defining the actual cause atrial fibrillation or...
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The actual other events and knowing whether it's a vascular disease.
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Once you've defined that there is an ischemic stroke, and you've actually done your CT and CT angiogram, what are the most common types of techniques you would then perform in those scenarios?
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Where do you go from there?
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Yeah, I guess we're trying to identify early the patients who will benefit from acute reperfusion or reopening the blood vessel.
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And there's two main tools that we have for that.
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So the first is thrombolysis.
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We've been doing that for 20 plus years in stroke care.
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And so thrombolysis lacks specifically on the fibre and to break down a clot.
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And the time window for that was initially four and a half hours.
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That's been extended to nine hours or nine hours plus in certain circumstances of favorable imaging.
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But thrombolysis is only so effective.
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So depending on the location and of the clot and the length of the clot, Thrombolysis may only work for around somewhere between 30 and 40 percent of actual vessel blockages to reperfuse the vessel.
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So it was recognized reasonably early on in the 2000s that thrombolysis, although it was a good treatment, it wouldn't work for, for everyone.
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And so In 2015, there were a series of five landmark clinical trials, pivotal trials that showed the benefit of endovascular therapy or clot retrieval, retrieving the clot through an endovascular route from the brain and showed the benefit of that in reducing disability.
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And the Royal Adelaide was involved strongly with one of those trials, EXTEND IA.
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The stroke and the interventional teams there in recruiting patients for one of those trials that were published in 2015.
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And the five trials showed a remarkable benefit for patients with large vessel occlusion or the blockage of a large vessel.
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And the number needed to treat was about two and a half.
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Which , in medicine is a very impressive number needed to treat, especially when we look at the actual number needed to treat for some of our other interventions and, and therapies in cardiovascular medicine.
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So incredible benefit in restoring function and reversing the stroke syndrome.
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So that's what's happening these days is the patients are going for endovascular therapy for clot retrieval.
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If they've got a large vessel ischemic stroke and salvageable brain tissue basically.
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And initially the window was four and a half hours and up to six hours in the initial trials.
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We've since shown trials that show benefit of endovascular clot retrieval up to 24 hours in select patients who have favorable penumbral imaging on their CT scan.
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So , when you do a clot retrieval, which vessels can you actually retrieve the clot from, and what does it actually involve, and how big is the clot you bring out?
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There's three questions that come to mind straight off as you're talking, and I'm in awe of this such amazing treatment.
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Yeah, and it is a remarkable treatment.
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I guess when I first went into neurology training, this was available only in clinical trials.
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And then you see the results of these patients who without clot retrieval would be left with a severely disabling stroke or even life threatening stroke.
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And some of these patients were leaving hospital a couple of days later.
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So quite a remarkable and seductive treatment, which is part of the reason that I went down a neuro interventional pathway.
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I really wanted to do what was being done because it seemed such a powerful treatment.
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And I guess once we've identified the vessel occlusion, they come straight upstairs to an angio suite.
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And, to compare to cardiology again, because, people have a reasonable understanding of what happens in a cardiac lab.
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It's very similar.
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So they'll come onto the angio table, there'll be an x ray tube around them.
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We'll get access either through the wrist or the hip, usually done under local anaesthetic plus or minus a little bit of sedation, but sometimes they do need to go to sleep for it.
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and then we'll pass tubes and wires up to the vessels of the neck and the cardiologist would go down and we'll go up basically navigate to the vessels of the brain.
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In terms of size and what we can do.
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So initially it was just the proximal large vessels that were involved in these trials.
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So we're talking internal carotid artery.
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M1, MCA, M1 occlusions, proximal M1 basilar artery occlusions.
00:19:23.114 --> 00:19:33.124
But now we're finding that we can go more distal more safely and techniques and technologies advancing so that our catheters and wires can go further out safely in the brain.
00:19:33.124 --> 00:19:42.943
Nowadays we're often retrieving clots from the more distal segments, M3 MCA segments in the ACAs as well, using smaller devices.
00:19:43.354 --> 00:19:44.943
And the clot that comes out is usually.
00:19:45.614 --> 00:19:46.703
Pretty small, to be honest.
00:19:47.213 --> 00:19:52.564
People, med students and trainees who come into the lab and you'll pull the clot out and they'll look at it and go, is that it?
00:19:53.394 --> 00:20:05.513
But, these are small vessels, they're, the vessels we're pulling them out of are usually somewhere between three and one millimetre, and so it doesn't take a big clot to cause a significant amount of neurological disability.
00:20:07.413 --> 00:20:08.894
It's amazing, it's really amazing.
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With the actual prevention side of things, I'll just, I'll get onto this for a sec while we're on the actual process.
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Obviously...
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We've talked about atrial fibrillation being a risk factor, but if you've got atherosclerosis in the large vessels, in the past, the people used to talk about doing endarterectomies.
00:20:25.003 --> 00:20:26.983
I Presume you can do stents and things for this.
00:20:27.144 --> 00:20:33.453
Also would wonder, also what about the people with vertebrobasilar insufficiency, and you've actually got blockage of the basilar vessels too.
00:20:33.463 --> 00:20:34.503
Can that be treated as well?
00:20:34.503 --> 00:20:37.443
There's plenty of people I see, where they extend their neck and they feel a bit dizzy.
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Is that a risk factor for strokes?
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And can that be treated as well?
00:20:42.624 --> 00:20:46.618
Yeah in the, in an acute stroke setting then the answer is quite simple.
00:20:46.659 --> 00:20:52.068
If you've got the blocked vessel, then the evidence is that if you retrieve and open that blood vessel then patients will do better.
00:20:52.398 --> 00:20:57.608
And some of the occlusions that we see there's the majority of strokes we see are embolic strokes.
00:20:57.618 --> 00:21:00.919
So the large vessel occlusion strokes are embolic, meaning they've come from somewhere else.
00:21:00.919 --> 00:21:03.909
So cardioembolic, atheroembolic for the, from the neck.
00:21:04.459 --> 00:21:16.808
If they're atheroembolic from the neck, then yes, sometimes we, to actually get access up there, we need to stent and balloon blood vessels to get access and so we treat the cause as well as removing the clot at the same time.
00:21:17.878 --> 00:21:21.088
To treat other conditions before they've had stroke.
00:21:21.943 --> 00:21:37.314
We still don't have great evidence for, so carotid stenting is one area where, they're starting to become equipoised with carotid endarterectomy, but we're probably still not quite there, so strictly speaking, carotid endarterectomy for carotid stenosis, symptomatic carotid stenosis is still the gold standard.
00:21:37.743 --> 00:21:47.919
But as devices and technology improvements, stroke risk of the procedure decreases, then we may get to the point where there's, there's complete equipoise or stenting is superior.
00:21:48.239 --> 00:21:55.808
Vertebra basilar disease is a bit more complicated just because the vessels, the vertebral arteries are smaller and often more tortuous.
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There was a trial previously looking at vertebral stenosis to balloon angioplasty, vertebral stenosis for symptomatic posterior circulation disease or insufficiency, but it didn't really show a clear benefit, , and so we don't know exactly where the line is yet with treating before someone has a stroke for these conditions.
00:22:16.979 --> 00:22:41.003
We know that medical therapies are effective but we don't know if we should be Stenting every patient that we see with a stenosis, the answer to that is definitely no and we're still finding the right patients to select and treat on a secondary prevention point of view, rather than treating them with, medicines and and lifestyle measures some of those patients, may benefit from intervention, but we're still, we still haven't worked out exactly who they are.
00:22:42.243 --> 00:22:50.653
And as I understand it, so then the embolic events are the main causes, and that's for either from atrial fibrillation or atherosclerotic vessels.
00:22:51.054 --> 00:23:01.354
And that's why treatment of cholesterol or an anticoagulation to reduce the risk of embolic events from atrial fibrillation, are the most important preventative measures at this stage.
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Is that correct?
00:23:02.989 --> 00:23:03.538
Yeah.
00:23:03.588 --> 00:23:04.269
Yeah, absolutely.
00:23:04.269 --> 00:23:04.489
Yeah.
00:23:04.499 --> 00:23:09.659
Preventative measures in general, the things that help with cardiovascular health will help with cerebrovascular as well.
00:23:09.659 --> 00:23:18.368
So daily exercise, limiting salt intake, balanced diet, some evidence for, Mediterranean type diet with, fish, vegetables, legumes, that sort of stuff.
00:23:18.719 --> 00:23:20.949
That's general advice that we would give everyone.
00:23:21.778 --> 00:23:23.749
And then there's other things that we can modify.
00:23:23.949 --> 00:23:25.878
For stroke, blood pressure is probably the big one.
00:23:25.959 --> 00:23:30.909
So blood pressure is where you probably get the biggest bang for your buck in terms of prevention, both.
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Because it's associated so strongly in a linear relationship with both ischemic and hemorrhagic stroke.
00:23:38.118 --> 00:23:44.979
And so there's definite evidence that if we're, treating blood pressure, treating hypertension, then we're, going to be reducing the incidence of stroke.
00:23:44.979 --> 00:23:47.699
So that's where you get often your highest benefit.
00:23:48.078 --> 00:23:54.398
But as well, treating cholesterol to target with statins, with with other exercise and diet as well as important.
00:23:54.818 --> 00:24:02.469
And then, as you say, if we identify certain factors such as actual fibrillation then specific antithrombotic therapy for that.