Febrile Seizures | Etiology, Pathophysiology, Clinical Features, Treatment

what's up ninja nerds in this video we're going to be talking about febrile seizures but before we get started it is extremely important that if you guys want to continue to support us because if you guys like this video if you benefit from it please continue to support us by hitting that like button commenting down the comment section and most importantly subscribing all right let's get into it all right so let's talk about the etiology and pathophysiology of febrile seizures now when we talk about these it's obviously a fever that is the trigger for the seizures right but what is causing that fever is the question and that's what's very important so it's primarily viral infection so it's primarily a viral infection that's a trigger what are the viral infections that you need to be thinking about the first one that i want you to be thinking about here is hv human herpes virus and particularly six you see this in a condition called rosiola infantum where they have a fever and they have this viral exantum a rash all over the place and they have febrile seizures as a potential complication the other one is h1 which is your influenza type of virus right and then the third thing is actually not as common but it can occur if you have some type of viral infection or if there was a recent vaccination and the particular one is the mmr vaccine or the dtap vaccine so the measles mumps rubella or the diphtheria tetanus and pertussis toxin vaccines so these are particular triggers when exposed to these types of things whether it be the virus or an attenuated form like a vaccine you can develop this kind of immunological reaction leading to a fever and then seizures can actually develop now not only is there an environmental component but there may be a genetic involvement as well particularly we tend to see these types of seizures and two particular things this is extremely important don't forget this we see this in a very particular age range six months to five years of age tends to be the most common age range where we see febrile seizures actually occurring and what's even more interesting is that we tend to see this in someone who has a child who had a family history maybe one of their first degree relatives a father a mother had a history of fibril seizures there is a high likelihood that they will also develop fever seizures so again quickly recap viral infection hhv-6 roseola infantin please don't forget that influenza vaccines like mmrdtap and again six months to five years of age with a family history first-degree relative who's had that now how do these things particularly lead to febrile seizures is the question right we should be asking that we're an engineers we think about these things so let's say that we're exposed to this actual virus whatever this actual pathogen in this case is where whether it be the pathogen or whether it be the vaccine when our immune system is exposed to this right you know macrophages they'll come they'll engulf the pathogen they'll take once they engulf the pathogen they'll express a piece of that type of pathogen on their actual mhc2 complexes right and once they express this on their mhc2 complexes they'll present that to t cells and then your t cells particularly your t helper cells they'll interact with that antigen via their t cell receptor and then they'll interact with the mhc2 complex via the cd4 positive proteins once this interaction occurs it triggers a cytokine type of release now these cytokines that are released include which ones you guys are going to be so good at this you guys will be able to see these cytokines in your sleep interleukin-1 interleukin-6 tumor necrotic factor alpha tend to be the most prominent cytokines that are released now when these cytokines are released they do a couple things one of the really interesting ones that i actually find the most interesting is that these tend to have the ability to act on very specific types of receptors present on neurons these receptors they tend to hyperactivate or increase the sensitivity of these receptors what are these little red proteins here called these are called let's break let's bring these up here these are called nmda receptors you're like what that mean man don't worry daddy got you so you know there's particular types of neurons called glutaminergic neurons these guys release glutamate and when glutamate is released it acts on these nmda receptors stimulating them right and when it stimulates these generally you'll have cations that'll flow into this cell when the cations load into this neuron what does it do to the inside of the neuron makes it super positive when you increase the positive charge within the cell enough that it hits threshold potential that can increase your depolarization so then you depolarize the cell then if you depolarize it you trigger these things called action potentials to move down the axon and this can lead to increased action potentials represented as eps these increase action potentials if they're excessive if they're synchronous this can lead to seizure activity man we good so what happens is these cytokines during the fever in this population tend to increase the sensitivity of this nmda receptor so every time glutamate binds more cations flow in more depolarization occurs more action potentials and seizures arise okay what else can happen because man we're on a roll here well you know what was the thing that we said there has to be a fever right well these things happen but guess what these chemicals here also act on a very particular structure located within our central nervous system sitting right here let's actually draw this one here in a blue color nice beautiful color here look at this i look good that's our hypothalamus the hypothalamus is kind of like our it has a lot of different functions but one of them in this role is that it plays a role in kind of regulating or modulating our body temperature when the hypothalamus is stimulated by these cytokines it triggers the release of a very particular molecule called pge2 that then will stimulate other parts of the hypothalamus to eventually increase working through different regulatory mechanisms increase our body's temperature when you increase the body temperature that obviously is going to lead to a fever right so that obviously that can lead to a fever now the problem with this is is that fever is going to increase your basal metabolic it's going to increase the metabolism and a lot of the activity of different cells within the body what do you think one of those cells are that's going to become a little bit more hyperactive a little bit more stimulated and it can then increase depolarization increase action potentials and potentially lead to seizures and we could so fevers potentially seem to work in that particular way now another thing that happens is that fevers you know what else they tend to do let's think really smart here fevers particularly increase your basal metabolic rate so let's actually go back to this they increase your basal metabolic rate what does that mean that means that you utilize more oxygen right so you're going to increase oxygen utilization and so because of that you're going to consume more oxygen so if you increase your consumption of oxygen you're going to need to bring more oxygen into the body to compensate for that consumption because of this increased basal metabolic rate so what do you do to bring more oxygen in i'm going to breathe faster and maybe even deeper so if i increase the reaction to this increase my respiratory rate and i increase the depth of breathing what am i going to do i'm going to in this process i may bring more oxygen into the lungs if i'm breathing quicker and deeper which will help to perfuse more oxygen into the blood but at the same time what is the other gas you know there's a particular type of relationship here that whenever oxygen moves across another gas has to move across and that is co2 so whatever type of oxygen is moving there's also going to be co2 moving and that co2 is going to be exhaled so as much of oxygen that we bring in the amount of co2 that we're breathing out so if we increase the co2 expiration what happens to the co2 levels in the blood as a respect to that you're going to drop them co2 levels baby and if you drop the co2 levels what is that formula so what let's let's think about that formula with co2 let's make sense of this acid base type of problem if you see where i'm going here right so co2 plus water i know you guys know this formula it leads to carbonic acid and then carbonic acid can easily and quickly disassociate into protons and into bicarb now think about le chatelier's principle we have less of this co2 if there's less co2 on this side of the reaction the chat ladies principle says that you have to shift the reaction to the side where there's less amount of substrate and so we're going to shift the reaction this way if i shift the reaction this way what happens to the amount of protons that are going to be present within the body well i'm using them to make co2 so then the protons will drop and this will cause my ph to go up because these are inverse so this is a condition called respiratory alkalosis now here's the problem alkalosis is a trigger for seizures so if that is the case and we cause this alkalosis type of effect this respiratory alkalosis may lead to seizures as a result of this man we good so what are the three things that i want you guys to take away from this within this pathophysiology one is that the cytokines can increase the sensitivity of the nmda receptors two increasing the body's temperature leading to a fever increases the basal metabolic rate of neurons increases the firing of them and three increasing the basal metabolic rate which leads to more oxygen utilization you'll have to breathe faster deeper you bring more oxygen but you get more co2 out leads to an alkalosis and alkalosis is a trigger for seizures boom roasted let's move on to clinical features all right so now let's talk about the clinical features we talked about the triggers what can lead to these seizures but now whenever these children six months to five years of age come in with seizures how will they present and how do i know if this is a complex fibroid seizure or a simple febrile seizure so simple fibril seizures it seems paradoxical but with simple febrile seizures they tend to be more generalized so they're going to involve both cerebral hemispheres so if you get both cerebral hemisphere involvement you can develop these first off generalized seizures so generalized and what does that mean when i say generalized it means you get more symmetrical involvement and when i say symmetrical involvement how do generalized seizures usually present with that classic case that you see the tonic clonic seizures in simple febrile seizures they present technically as a tonic clonic type of seizure so a very big thing to remember there so two things i want you to take away from this is it's a generalized seizure that usually leads to a symmetrical involvement meaning you get upper and lower extremity involvement in a particular tonic clonic type of fashion the next thing that i need you guys to remember is that the time frame is also very crucial the duration of the seizure it tends to be in simple less than 15 minutes in duration it's usually no greater than 15 minutes in duration for the seizure the other thing is it's how frequent the seizures can occur so if someone has let's say a simple febrile seizure that last less than 15 minutes would they develop another seizure within a 24 hour period no it's usually one seizure in 24 hours no more than that if there's greater than one seizure in a 24-hour period it's not a simple febrile seizure it's more likely a complex fibrous seizure so again big things to take away simple fibril generalized tonic clonic symmetrical movement less than 15 minutes in duration and you don't have more than one in a 24 hour period let's talk about complex febrile seizures complex fibroid seizures tend to be again a little bit paradoxical here tend to be more focal so they usually have one type of hemispheric involvement not bilateral so this tends to be more of a focal type of seizure and so you get more unilateral type of involvement and again this may present with a unilateral tonic type so it may present with a unilateral tonic type it may present as a clonic it may present as a a tonic or it may present as a myoclonic type okay so these are big things to remember here now when they have this focal unilateral abnormal type of movement that's present because it's again usually one hemisphere focal in nature how long will these occur well think about it that was less than 15 what do you think this one is greater than or equal to 15 minutes so if the duration that these children are seizing and this focal type of seizure is greater than or equal to 15 minutes it points to a complex febrile seizure or if they have greater than greater than one great we can actually say greater than or equal to one one seizure in 24 hours that points to a complex febrile seizure so again simple fibroid seizures remember it is generalized tonic clonic symmetrical movement okay complex fibril it's focal unilateral abnormal movements uh simple fibril is less than 15 minutes in duration and usually you don't have more than one in a 24-hour period complex vibra greater than or equal to 15 minutes and you have more than one in a 24-hour period last thing is that both of these can develop a post-ictal type of state a post-ictal state for these are usually no greater than and this is extremely important this usually lasts about five to ten minutes and usually we characterize this as kind of being drowsy maybe even a little bit confused so their this mental status is a little bit reduced it's very important to remember the time frame it usually doesn't go more than 10 minutes if someone has drowsiness or confusion the level of consciousness is declined for more than that period of time you may want to be thinking about an alternative type of diagnosis okay so these are the big clinical features let's talk about diagnosis so diagnosis when we talk about fibro seizures the big thing is to take a look at your physical exam their history did they recently have a viral infection like a week ago did they have any kind of vaccination about a week ago did they have any family history of febrile seizures that's a quick thing within the history that we can think about physical exam findings that usually point more to an alternative diagnosis is something to quickly rule out is their level of consciousness significantly declined but it's been declined for more than how long potentially 10 minutes that points to alternative diagnosis okay so this is particularly maybe an alternative diagnosis the other thing do they have any other signs like meningeal signs what are meningeal signs because that can also point to an alternative diagnosis do they have any neck stiffness do they have any headaches do they have any photophobia or phonophobia do they have the positive kernigs or the brzezinski's test that could be pointed to an alternative sign the other thing is think about their vital signs so did they have any abnormal vital signs was there any significant hypoxemia was there any hypotension are they having a fever these are things that may point to maybe this could be a simple febrile seizure or complex fibril seizure and the last thing is look for any viral examples what does that mean you know when someone who has rosiola infantum they have a lot of that rash all over their body they have a fever they have this ration they can develop seizures that may point to that or you know in someone who has coxsackie virus which can also be sometimes a cause they may have herpetic lesions in the oral cavity so again look for any kinds of signs that may point to more of like a respiratory or some kind of viral example or viral disease that may be related here once we've done that we've gone through our physical exam we really want to think about this it's usually an infection that potentially could be the cause and once we find the infected source we may just have to like you know treat that so what is the potential things that we can look for infectious sources in a patient the first one is let's say that we want to make sure that there's no urinary tract infection especially in children if there is a urinary tract infection how would we check that do a urinalysis a ua and then you can also do a urine culture boom we just determined if there was a uti potentially present okay the other thing is what if there's some type of gastroenteritis of some kind there's some type of gi tract infection so maybe there's a git infection of some kind what can i do here we'll look for maybe any inflammation of the bowel walls you don't want to get ct scans in children so one of the best thing to do is do ultrasound so sometimes performing a abdominal ultrasound can be kind of a nice go-to test here the other thing that we don't want to miss is is there any infection like pneumonia or any kind of like viral pneumonia of some kind i don't want to miss anything like that how can i do that get a chest x-ray so these are quick little things that i can do to try to find where is if there is an infectious source where is it let me rule out any really nasty ones because then i can address that issue once we've ruled out these things the next step that you go to is you can start to have another kind of thing that you need to be thinking about simple fibril seizures don't usually like require a very thorough workup to be honest with you sometimes they won't even require this kind of workup complex febrile seizures generally require kind of a more kind of underlying evaluation for infection be the things that we talked about but a complex fibral seizure may also require some imaging some even more invasive studies so one of the quick things that we should do though is obtain some blood work when i obtain some blood work one of the things i like to look for is i like to look at the sodium okay the reason why is that if someone has low sodium hyponatremia there has been literature that suggests that this can trigger febrile seizures the other thing i like to look at is i like to look at two things i like to look at the glucose within the blood and maybe blood cultures and the reason why is we're going to talk about that right here if you obtain glucose and you obtain blood cultures you probably are going to compare this to a lumbar puncture again lumbar puncture unless this is a complex fibral seizure or you suspect an alternative diagnosis like meningitis or encephalitis of some kind then you should perform a lumbar puncture and run through these cultures run through at the glucose level you're going to check the proteins you're going to do all of that stuff you may even run a viral panel the whole nine yards on this just to make sure that you rule out any meningitis rule out any encephalitis or any other kinds of negative events here when you do that you generally like to take the lumbar puncture and compare like the glucose to the glucose in the blood generally if it's a bacterial infection glucose within this area will be lower and then it will be much much lower compared to the serum glucose okay also blood cultures was there any infection that was in the actual blood and maybe it spread to the central nervous system comparing to that culture is there okay so again look for the infected source ua urine culture we can do an ultrasound of the abdomen we can do a chest x-ray we can get checking glucose and blood cultures and using that to help with our assessment of the lumbar puncture looking for hyponatremia the last thing is what if we want to rule out any structural lesions what if there's some type of structural lesion here present well then that's where a ct or an mri can come in handy and the last thing and probably one of the most important ones that you need to obtain some with a complex febrile seizure is an e e g an electroencephalogram to look to see if there's any electrographic representation of these seizures okay so that covers our diagnosis so the last thing that i want us to talk about here is treatment so we've gone through we've figured out the potential triggers we've talked about the clinical features we've gone through our diagnostics we've come to the point where we said okay this is a simple fibral seizure or a complex febrile seizure usually these seizures will not require treatment usually they'll abort on their own in about five minutes but if this is greater than or equal to five minutes or it's a complex type of febrile seizure it's probably going to require some abortive therapies what is the first line they ask you on an exam what is the first line thing for someone who has a fibroid seizure it's been seizing for more than five minutes or it is complex in nature you say lorazepam so giving them a particular type of benzodiazepine called lorazepam is your first line alternatives include midazolam you can give this if you don't have any like iv access or diazepam okay how do these drugs work they're very simple they're acting on gaba receptors you know on these actual neurons here let's say that this is the neuron that's you know triggered here and it's the one that's triggering a lot of these like action potentials and seizures well if we shut down these seizures what we can do is we can have this neuron you know it releases a molecule called gaba so this is a gaba neuron it releases lots of gaba these drugs here lorazepam midazolam and diazepam will act on particular sites on these gaba a receptors and make these gaba-a receptors more sensitive and so whenever gaba binds onto these actual receptors they open up more intensely and allow for chloride ions to flow in to this actual neuron that leads to lots of negative ions coming into the cell lots of negative ions lead to what hyperpolarization it makes the cell super negative if you hyper polarize the cell will you lead to action potentials no it's going to decrease the action potentials aps which may decrease the seizure man we good all right the last thing that i want us to talk about here is if you've aborted the therapy okay you've given a board of therapy because they've seized for more than five minutes or a complex febrile seizure is present the other thing is addressing the fever generally these are viral infections it's primarily a viral infection that's why generally this diagnostic workup this may be overboard you may not have to perform a lot of these things it may just be looking at the history in the physical exam if it's complex fibroid seizure you may have to do this workup or if you have an alternative diagnosis that you're thinking about you may have to do this but generally these are viral infections that will respond well without any antibiotics without any antivirals all they need is just some drugs that are going to reduce their fever what are drugs that reduce fever guys insteads right avoid aspirin why do you avoid aspirin and viral infections because of the risk of rye syndrome so you avoid aspirin but you can give things like other types of nsaids right so ibuprofen ketorolac you can give naprox and things like that another drug that's preferred really is acetaminophen okay so this is kind of like the preferred one that's your tylenol that's the preferred one but either way how do these drugs work simply put virus we said triggers these immune system cells they released all of those cytokines the interleukin-1 the interleukin-6 tumor chronic factor alpha that stimulated the hypothalamus the hypothalamus released some chemicals like pge2 that reset the body's thermostat and lead to a fever well we got to kind of zoom in on that hypothalamus really quickly and see what happens you know within the hypothalamus there's some endothelial cells so this is kind of like a this is a part of the hypothalamus right it's kind of like the endothelium or like the epithelial cells of the hypo thalamus from here there's a membrane within the hypothalamus and what happens is it break it breaks down the membranes break down and then the lipids are get metabolized by this molecule called phospholipase a2 phospholipase a2 will break down this into what's called arachidonic acid and you know arachidonic acid it uses this enzyme called cyclooxygenase abbreviate a cox keep your minds clear this will convert arachidonic acid into what's called prostaglandins and you know one of the prostaglandins that we talked about was prostaglandin e2 if we give these drugs nsaids or we give acetaminophen they inhibit the cycle oxygenase enzyme you can't convert arachidonic acid into prostaglandins you drop their pge2 level can you trigger a fever now no there should be a reduction in the fever and that is all we need to know about febrile seizures all right ninja nerds in this video we talk about febrile seizures i hope it made sense i hope that you guys enjoyed it as always until next time [Music] you

Channel: Ninja Nerd

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Id: LDvPlEi2DwE

Length: 27min 37sec (1657 seconds)

Published: Mon Aug 09 2021