Stroke Podcast 2/2

Welcome back to the second part of the podcast on stroke with surgeon Captain Winnie Wilson. In the first part we had talked about the various mechanisms of stroke, various etiologies depending on the age group of the patient. We also considered various aspects to be asked from a patient as far as history is concerned when he or she presents with a syndrome suggestive of a stroke. In this part we shall now get into the details of examining such a patient and thereafter various investigative modalities to confirm the diagnosis of stroke and then get into the aspects of management. In these two parts of stroke we shall comprehensively cover this very important and clinically relevant topic and I request these students to make notes and also come back to us in case there are certain issues that they would like to discuss and get more details on. Surgeon Captain Winnie Wilson the professor of medicine and neurologist in the Department of Medicine AFMC has been with us for the first part of this stroke and now we welcome him back for this second part. Thank you sir I'm more than willing to answer any questions that the students may have. Till now what we have if I can just summarize what we have addressed is that stroke is an abrupt appearance of a neurological deficit which has a vascular mechanism. We've also discussed the various mechanisms which can cause strokes. We discussed the various causes that can lead to stroke depending on what is the age of the patient and if there is an underlying inherited disorder we suspect based on family history then there are certain conditions which can cause stroke. Now we have a patient we have suspected stroke and we also understand that stroke is a clinical diagnosis so we've encountered a patient in whom we suspect and have clinically diagnosed him to be having stroke. So what are the things in examination that as a physician I should look for to further go ahead as far as managing this patient is concerned? A general examination is very important because that is something that is usually kind of overlooked by resident training or even the young doctor because it is a common misconception that one may not get enough clinical clues or it may not make a major dent into the management of acute stroke. However I cannot overemphasize the importance of general examination because many clues and the paths that the stroke management takes can come from your general examination findings. The most important of which include the pulse, the examination pulse and the pulse is irregular, the possibility of raised, the possibility of an intermittent atrial fibrillation comes to fore and one should be, one should go all out to look for any absent pulses especially the dorsalis pedas and such a patient because if the peripheral pulses are absent it is quite possible that this patient had an intermittent AF and he had embolized clot in the distant past. Similarly while examining the pulse one should not forget the asymmetry of pulses especially in a young Indian woman where tachyous wateritis would be an important cause for a stroke and while examining the pulse never forget to look for a bruit which you can look in the neck with the pellet stethoscope. Bruits are also heard on the base of the neck in certain vertebral artery dissections or vertebral artery pathologies. Sometimes bruit can also be heard over the closed eye colonocular bruit. Blood pressure examination is also important because in a acute stroke the blood pressure is a very important aspect of management of that stroke patient because it is not only a risk factor for stroke the management of blood pressure in hemorrhagic stroke is very different from the blood pressure management in the ischemic stroke. Similarly while examining the patient if you find that one pupil is constricted and the other is dilated and the patient has had a stroke this may be aneurysm that is ruptured especially the PCOM aneurysm. Also during examination if you find the patient has ecumoses or petticea then you should think of especially necumoses to think of an anti-cogland use for whatever reason could be a triflopilation in the past or any other cause and anterior axillary fold petticea point towards probability of a fat embolism in the past or fat embolism in the recent past. Similarly because ethrosclerosis is the most common underlying pathology one should look for all the markers of ethrosclerosis including tetanine xanthomas xanthylisomas some infections which can cause stroke may have their peripheral markers very evident and they should not be missed. Some neurocutaneous markers like facial hemangioma sometimes hidden behind an eyebrow can be an important clue to the AV RT2 venous malformation in the brain and if present should be noted in general examination. So it's a very comprehensive list and in fact it's very important because it can give us very essential clues towards the diagnosis. We also understand as you already mentioned once earlier that time is of great importance while we go about diagnosing and managing strokes so I think it would be worthwhile for the listeners to have some kind of a checklist in their hand when they take history and do the examination in patients with suspected stroke. Now once you've diagnosed stroke and gone about examining patients we understand that time is great so what are the things that one should immediately address while managing such patients. So the first and most important thing is to recognize stroke and today the emphasis is for the lay person in the community in the mall in the realization of the airport to recognize stroke and there is an increasing awareness among general population about strokes and it is a common practice today to bring the patient within the couple of hours of stroke onset to the hospital. In the emergency it is very important to again recognize the abruptness of the event which can come from the history. The patient may be eating and suddenly develops hemiparesis and the focality which we discussed earlier the acronym BFAS can be applied in the emergency and it is also important to pinpoint the time of onset by repeatedly asking the patient and ascertaining the veracity of the time onset because the stroke management entirely depends on the time window that you've got from the onset to the presentation in the emergency. Whenever you suspect a large vessel stroke based on the discussion we had earlier in the form of the particle symptoms then in a differential weakness then one must kind of alert the neuro intervention team because these are those kind of strokes that may be amenable to a endovascular intervention where you can extend the window beyond the traditional window period for thrombolysis. A large vessel stroke can also be suspected when the National Institute of Health Stroke Scale is a large number so the total scale is out of 42 if you get a large number like 16, 20, 24 then this is also an indication that this patient may be having a large vessel stroke. It is very easy to do this NIH's certification today it's about two hours you spend on the internet the certification is free and now apps are available to the scale. In the emergency one was also ruled out a hypoglycemic event and God forbid if the patient is taking warfarin or any other anticoagulant it is important to do a INR because if the patient is on warfarin and the INR is less than 1.7 the patient may still be amenable to a thrombolytic therapy. After while this is going on the assessment is going on the CT team should be the radiology team should also be alerted and the patient should be immediately be moved for a non-contrast CT of the head. So we now come to a point where we have assessed the patient both as regards the history as well as the initial examination. One important aspect of assessment of neurological conditions is neuroimaging and we use two modalities commonly that is the CT scan and the magnetic resonance imaging. So when it comes to stroke what are the role that is played by these two modalities? CT scan plays a very important role even though I've emphasized earlier that the stroke is in clinical diagnosis but a CT scan is mandatory in or an MRI is mandatory before we go ahead with the thrombolytic therapy because it is not clinically possible to 100% differentiate a ischemic stroke from a hemorrhagic stroke. So to ascertain whether the patient is having ischemic versus a hemorrhage the definitive thing is the radioimaging. So it is not to diagnose a stroke but to ascertain whether the patient is having a hemorrhage or a ischemic event. There are two protocols that are available in the country. Majority of the centers use a CT-based protocol for the simple reason that CTs are easy to start whereas MRI it takes time to boot at least half an hour to boot and CTs are available in more centers than MRI is available. So the CT is done as fast as possible once the patient is wheeled into the emergency and the role of CT as I mentioned is to rule out the presence of hemorrhage and once the hemorrhage is ruled out the patient should immediately undergo a CT angiography in the same setting and the idea of doing a CT angiography is to look for a large vessel occlusion. MRI on the other hand can be useful in certain conditions especially when the patient has woken up with the stroke which is usually referred to the wake-up stroke and when the stroke onset time is not exactly known and in certain subset of patients to kind of establish that there is an ischemic penumbra that exists and in them we can selectively offer a revascularization procedure. Great actually this this concept is very interesting and from what little I could understand is that's one part of the damaged brain that can be salvaged so that makes it very important for us to actually recognize it and address it as soon as possible so what is can you elaborate on this concept of penumbra for the audience. So whenever stroke occurs there are two aspects to the area of the stroke the functional deficit of the patient is caused by both the ischemic core and the penumbra. Now core is that part of the stroke in the brain where the blood flow is below the the critical blood flow which is 8 ml per 100 grams per minute so whenever the blood is flowing lesser than that in a particular area of the brain it leads to infarction of that brain and that portion of the brain is not salvageable so that dead brain is called the ischemic core whereas surrounding the ischemic core is a perfusion of blood which is little more than the critical blood flow and it usually ranges between 8 ml per 100 gram per minute to 18 ml per 100 gram per minute and this surrounding area around the ischemic core is usually supported by the collateral circulation and this collateral circulation maintains a viability in in the penumbra and the penumbra supported by the collateral can lead to a functional deficit but is not completely dead and hence all interventions are aimed at salvaging this penumbra that is still perfusing kind of a stunned myocardium the equivalent of a stunned myocardium in the brain and interventions are directed at salvaging this penumbra. Okay in fact that's where we can actually cause improvement in the patient's neurological deficit and and make a difference so why is there this concept of a time when we say that we need to address it quickly because time is brain so how did how does this concept of time window actually come come about. So the concept of time window came out of animal experiments where on including the MCA it was found that beyond if those occluded MCAs the medicinal arteries were released after three hours no part of the brain could be salvaged. Subsequent trials in humans actually proved this concept however the window was increased from the initial three hours to 4.5 hours and it has never gone beyond the 4.5 hours because the risk of bleed when one tends to thrombolyze the patient beyond the 4.5 time window for thrombolysis and the agents used for thrombolysis include alteplase and tenecteplase, alteplase is an infusion over one heart and alteplase is a bolus injection many centers prefer tenecteplase over alteplase because the ease of administration and they are more or less equivalent in their efficacy. The time window for mechanical intervention as in endovascular intervention is traditionally 6 hours but recent trials have extended to beyond 6 hours even up to 24 hours. Great so since the time thrombolysis has become popular in strokes and we've seen the heartening results that happen and there's always this keenness to find out whether this patient can be thrombolyzed and how quickly we should do it but at the same time are there any contraindications to thrombolysis that we should be aware of where we may actually end up doing more harm than good by doing the thrombolysis. So when thrombolysis had become the the list of absolute contraindications used to be a large list over the years many of those absolute contraindications have been removed as on today some of the absolute contraindications include a prior intracanial hemorrhage, a structural cerebral vascular lesion, a malignant intracranial neoplasm, an ischemic stroke that has occurred within the last three months, a suspected aortic dissection, a patient who has active bleeding ongoing or bleeding diathesis, a close head trauma or a facial trauma that has occurred less than three months. Apart from these there are relative contraindications where the clinician can take a decision on whether to thrombolyze or not to thrombolyze certain conditions like if there is bps with more than 185 by 110 is a relative contraindication similar similarly pregnancy is a relative contraindication there are many similar age more than 75 years relative contraindication. So these are contraindications where the the clinician can take a case-to-case based decision. Okay so although thrombolysis being such a promising way to address strokes and we also understood that there are certain situations where we should avoid or at least have a very careful consideration before we actually thrombolyze the patient but once we thrombolyze the patient are there any things that we should monitor the patient for and what are we worried about at that stage? So the most dreaded complication after thrombolysis is definitely the intracerebral hemorrhage and that is a complication that we dread because of the fatality that accompanies it. So all patients who undergo thrombolysis should go through this checklist of contraindications first of all the the absolute onset of time should be ascertained and the patient should be shifted to ICU before the thrombolysis happens. The aspirin if not given to the patient should be with health for 24 hours and the patient should be monitored through the thrombolysis and post thrombolysis with Serial National Institute of Health Stroke Scale Assessments and a repeat CT scan of the head is warranted whenever this scale versus by a number of four or when there is a dip in sensorium and on a repeat CT scan if hemorrhage is detected the thrombolysis should be immediately stopped if it is already ongoing and a neurosurgery consult should be taken for whether the patient would require a decompressive renalectomy which may at times be life saving. Okay so apart from thrombolytic therapy where a drug is used to break the clot we also know about a mechanism of addressing these clots by way of mechanical thrombectomy. So in patients who are amenable to such procedures for in an ischemic stroke what percentage of patients actually qualify for this mechanical thrombectomy which I understand is basically done by interventional radiologists. So mechanical thrombectomy has come to 4 in the last 10 to 12 years and before 2012 before 2015 mechanical thrombectomy had gone to disfavor because the none of the trials had shown positive results. However the trials after 2015 has shown that if you select a population amongst stroke who has a large whistle occlusion and we discussed about the characteristics of a large whistle occlusion earlier and if you are able to demonstrate a large whistle occlusion in angiography either through DSA or CT angiography then these are those patients in whom if you do a endovascular intervention in the form of a mechanical thrombectomy with the newer devices like solitaire and stent retriever devices then these patients will benefit. However the percent this subset of population they constitute about 10 to 20 percent of all ischemic strokes coming to an emergency so it's not that every patient ischemic stroke can be subjected to an endovascular intervention so demonstrating a large whistle occlusion is a prerequisite. Also the mechanical thrombectomy by way of endovascular procedure requires trained manpower and DSA digital subtraction angiography facilities off late more and more neurologists in addition to the already existing intervention radiologists are doing this procedure and time will come where neurosurgery is also interested in this procedure and this will open the flood gates and the procedure may be available at more and more centers even at periphery. Okay so we have understood the benefits that by way of either pharmacological thrombolysis or a mechanical thrombectomy that ischemic strokes can be addressed and the deficit can be reduced. The problem in stroke that we often encounter is that patients do not reach in the time that we have known as a classical window period so what's the rationale of extending this time window which can probably benefit more number of patients even if they present at a later period. Recently the time window has given way to a new concept called tissue window and this concept of tissue window has come into the medical literature because earlier the role of collaterals in the in stroke was not that well recognized because of better imaging modalities it is now well recognized that a smaller subset of population has a good rich supply of collateral surrounding the ischemic core and these collaterals can support that ischemic penumbra for up to 24 hours so in that subset of population only where you have a large vessel occlusion and one can demonstrate a penumbra beyond the traditional six hours which are allowed for mechanical thrombectomy then these patients can be subjected to an endovascular procedure up to 24 hours and this was born out by two famous trials namely the dawn trial and the diffuse trial which came as late as 2018 and they have conclusively demonstrated that in a small very small subset of patient who have large vessel occlusion and evidence of penumbra as demonstrated by imaging techniques or the clinical imaging mismatch one may go ahead with interventional procedure even beyond six hours up to 24 hours. There are various ways of demonstrating this penumbra and this includes clinical imaging mismatch or a diffusion perfusion mismatch or a diffusion flare mismatch which are radiological techniques that one may resort to in establishing this penumbra even when the patient is presented beyond six hours and a patient who has a large vessel occlusion. Okay great so I think we've addressed the concept of ischemic strokes very comprehensively and I think in much greater detail now if we go back to the point in time where we started evaluating strokes with neuro imaging and we do a NCCT of the brain and we find that there is a hemorrhage now in patients who present with intracranial hemorrhage as the cause of their stroke what is the way one should proceed ahead with these patients management. So the moment the patient is taken to a CT gantry and you find that the CT images that are coming on the screen has a hyper dense kind of quality that is an indicator for a hemorrhage. The moment you see a hemorrhage on CT thrombolosis is out of the window endovascular procedures are out of the window one has to ascertain the location of the intracerebral hemorrhage so if the location is around the basal ganglia in the thalamus in the cerebellum in the pons then one one can be fairly certain that this is due to hypertension. However if the hemorrhage is in the loba in the frontal lobe or the temporal lobe if it's a loba hemorrhage then one has to think of causes beyond the usual hypertension and these causes may be either an anti-cogulent overuse or a patient has taken a drug for example narcotic drug or the patient has an AV malformation that is a bled or it could even be a cerebral venous thrombosis which is where the bleeding occurs beyond a particular vasculotent. Another indicator to presence of coagulopathy is a level that one gets to see within the hemorrhage eclation a horizontal line which is not the case with hypertensive hemorrhage. So if coagulopathy is suspected as to the cause of bleed for example if the patient is on warfare and he has overdose himself and the aina has come very high and you find a lesion which is you find hemorrhage which is in the lobes as against the basal ganglia then this may be the kind of candidate in whom you would want to give vitamin K and fresh frozen plasma. On the other hand when the patient CT shows a sub-arachnoid hemorrhage they look for an aneurysm immediately do a CT angiography or subject him to a digital subtraction angiography and what if one finds a neurosome then emergently that neurosome should be clipped or it should be subject to an endovascular procedure of coiling. If the cause of hemorrhage is arterial venous malformation then this lesion has to be excised and a neurosurgery consultation should be required. So various types of stroke that we discussed it now involve the arterial circulation whether it's an ischemic stroke or hemorrhage. Now there is a less common however definitely far different from an arterial stroke is a subset of venous strokes where the manifestation as well as management may differ. So I would like you to briefly tell us that how differently do they present and how differently should they be managed? So unlike the arterial strokes it is very important to recognize the venous strokes because venous strokes tend to have much better prognosis than the arterial strokes and if treated well in time appropriately these patients come out of this venous strokes with almost no residual deficit. Some of the clinical clues to the presence of venous stroke is a hemorrhage in the brain which is not confirming to a vascular territory. So presence of hemorrhage is the first indicator. Second if one finds there is a blood clot in the dural sinuses this can occur in the form of hyperdensity in the confluence of sinuses or it can occur when a contra CT is given and there is no filling in the in the dural sinuses. This often referred to as an empty delta sign can be again an important clue. Clinically stroke that has started with the seizure is more likely to be a cerebral venous thrombosis than an ischemic stroke or an arterial stroke. Also the setting in which the patient has got a stroke for example if the stroke has happened in a young lady who is pregnant or a lady who is in properium or a person who's gone for a recreation to high altitude or is deployed there for whatever reason these are the subset of patients where venous stroke should be suspected. Once diagnosed the patient should be started on anti-coagulation as against anti platelets that we usually start for arterial ischemic arterial strokes. Great. So one must understand that venous strokes are a totally a different ballgame when it comes to the mechanism which is underlying as well as its management and most importantly the prognosis of the stroke eventually. So that's where the issue of differentiating them from arterial strokes is so important. One important risk factor for strokes is underlying blood pressure and when it comes to managing strokes addressing blood pressure becomes a very important aspect. So compared to acute ischemic strokes when we manage the hemorrhagic strokes what is the way we address these blood pressures and what are the various targets? So while one should be very proactive in reducing the blood pressure in intracerebral hemorrhage preferably to 149p or somewhere about that but in acute ischemic strokes the blood pressure and the outcome follows a J-shaped curve where if you reduce too much then the morbidity and mortality increases and you let it be very high again the morbidity and mortality increases. So you have to strike a balance and especially in the first 24 hours it is one should be very conservative in lowering the increased blood pressure in acute ischemic strokes because that is the pressure head against which the perfusion is happening within the brain and if you lower this pressure head by correcting the blood pressure then the ischemic pore is likely to expand more and more blotting out the whatever little viable penumbra there may be available to salvage. I think we have addressed the concept of stroke in a great detail and in fact the information that you have shared with us makes us wiser on what are the various types of stroke depending on the age and the mechanism and also the way we must go about managing these patients to ensure that there is minimal residual damage. So when it comes to stroke the aim is to have least amount of neurological deficit in the patient and make him make him as functional as possible. However in quite a few situations we are not able to achieve that favorable conclusion. So when we follow these patients subsequently our targets are one we make him as functional as possible and two also ensure that it doesn't happen again. So if you could just summarize the management of a patient of stroke after this acute period of management is over. So once the patient has survived the acute period through the thrombolysis and through the life-saving surgeries it is very important to identify the risk factors that has caused the stroke. It may not be possible in every patient despite the extensive investigation but all-out effort should be made in identifying that risk factor because a patient who has had a stroke is at a very high risk for getting a subsequent stroke that may be even worse than the first episode of stroke. So all-out efforts must be spent on investigating and identifying the risk factor and that risk factor may be in the form of a inherited thrombophilia. It depends on the age profile of the patient and we have discussed those etiologies earlier. So investigation should follow the age patterns and the various large vessels, small vessels and all those considerations should be met here. Once a risk has been identified then a decision should be taken whether to mitigate that risk or not. It is easy in certain conditions like diabetes, dyslipidemia, hypertension, obesity, sedentary life habits or drug abuse or alcohol binge. In certain other conditions it may not be that straightforward. For example, mitral valvular collapse was once upon consider to be a very important cause for strokes but now off late the consensus is not so clear. Similarly when encountering an infective endocarditis, a definitive surgery versus antibiotics is is a considered take of the clinician. A mixoma that has not so far embolized or has embolized causing only a TIA one has to be one has to take a clinical decision. We recently had a patient who had a mixoma multiple episodes of strokes leading to bleeding and one had to take a considered decision as to whether to subject this patient to a definitive surgery to remove the mixoma because the surgery involved giving her parent and the patient had already blood in the brain. Similarly keratin imaging is very important because if there is a significant stenosis then that has to be tackled either by endotectomy which is a surgical procedure or by keratin stenting which is an endovascular procedure and I would like to put a lot of stress on the rehabilitation portion of the stroke management because the the most definite thing that is going to happen if the patient has survived is that the patient is likely to get spasticity and when the patient gets spasticity that whatever strength that patient is going to recover and there will be recovery of strength because of neuronal plasticity whenever the strength comes back maybe a month later maybe three months later maybe even one year later if that return of strength is accompanied by spasticity that limb will be useless to that patient because of spasticity so all out effort should go to prevent the development of spasticity in this patient and it is recommended that a stroke patient should undergo physiotherapy from day one of stroke and the importance of rehabilitation should be emphasized not only on the patient but also the relative many times when the patient goes home because the patient starts developing spasticity and the physiotherapy becomes painful because the spasticity patient gives up the relative give up but it is that is where your counseling helps and somebody who has undergone through a good rehab is likely to recover a major portion of what is lost by way of stroke great we have come to the end of this very comprehensive and elaborate discussion on management of strokes we also understand that this information is mainly directed at our students who are in the process of becoming physicians and neurophysicians of future they have two major interests in mind as far as gathering such information is concerned one what should they be aware of when they write a answer to a question on stroke in the examination that they are going to face soon and two tomorrow as physicians or as medical officers when a patient of possible stroke comes to them under their attention what are the key factors that they must remember and not forget at all so I before we conclude I just want you to point out a few things and flag them so that that they become like sort of take home points for these students to remember so as far as examinations are the university examinations are concerned the student should be well versed with the vascular anatomy of the brain the presentation of the stroke which is abrupt and focal in nature that should be brought out the acronym B FAST should be remembered and should be expanded and if possible the presentation vis-a-vis the localization in the brain should be emphasized upon and finally the risk factors when compared with the age profile of the patient and how to approach this patient in the emergency the importance of saving time and doing a CT scan on time as fast as possible and taking a decision on a definitive acute stroke management by way of thrombolosis or mechanical thrombectomy should be brought out and finally the role of secondary prevention and rehabilitation should be brought out in a clinical in a university examination as far as practical for the point is concerned the student should be able to recognize a stroke and that is the most important thing a patient comes to emergency a stroke should not slip under his nose he has to recognize it and that is the most important thing and once you have recognized it rest of the workflow is relatively easy so if you have recognized stroke then the stroke pathway is clearly laid out CT scan image plain CT angio decide between thrombolosis or endovascular management permitting the given the time windows whether they're permitting or not and once that is done monitor the patient involve the neurosurgeons involve the neuro radiologist and once the acute phase over investigate for etiology and emphasize on rehab with this we come to the end of the series of two podcasts on the topic of stroke with surgeon captain many Wilson the endeavor has been to provide you with credible information in a very simplistic way to address a very important and clinically relevant topic my request to students is that please listen to these podcasts whenever you have time whenever you feel that you need to revise these topics because these are things which you need to learn over and over again to become experts in this field it will also ensure that when you go ahead and appear in exams or are in front of a patient who needs your treatment will you will be more confident to handle these issues then if you've heard these podcasts and and topics being discussed by experts in the field so lucidly I also request all the students to river to us with their feedback about how they felt these podcasts would improve the way they learn medicine you also want you to come back with any queries or doubts that may still be lingering in your mind about these topics you also want you to tell us which are the topics you would like to be covered in such a podcast and in fact you may also tell us who's the faculty you would like these podcasts to be addressed as far as these covering these topics are concerned and I'm sure as a department which is interested in ensuring that our students become wiser more learned and do well in the exams I will ensure that you get these faculty addressing these topics in these podcasts thank you very much and we look forward to your greater involvement in this learning process