Consciousness & Coma

hey there guys this is dr. James Harrington and today we're going to talk about a decreased level of consciousness and coma and some associated symptoms so there are a lot of words that can be used to describe a decreased level of consciousness ranging from confused or agitated down to unconscious and comatose but there are some specific meanings to several of these terms that I think it's important we recognize to begin with delirium delirium is an acute confusional state that is fluctuating in course it can include attention deficits and disordered thinking it can be a product of poor focus which in the clinical sense is particularly notable when a patient can't focus on the clinical exam and this tends to connote a psychiatric process or the psychiatric quality of a process but functionally this is the same thing as encephalopathy which we'll talk about in a moment now delirious patients can have disordered thinking and they can be disoriented to time place and persons usually in that order so what will commonly see this in is an older individual so in our geriatric patients they will think that it's 10 or 20 or 30 years before the current date if you ask them who the president is they'll tend to name people like George Bush Senior or Ronald Reagan or Bill Clinton as they become more confused they'll be uncertain or disoriented to place and usually they can figure out that they're in a hospital which is often where we're examining them but they usually can't figure out where that hospital is and sometimes they won't know the state they're in and lastly as they become profoundly disoriented they will no longer recognize the people they're with sometimes they will married women in particular will revert back to their maiden name they may recognize the people around them as individuals they know but they may not remember their names or exactly how they're related furthermore they may suffer from hallucinations or delusions and this can also often cause agitation and also realize why we're talking about this that this kind of delirium can mimic a right cerebral stroke or seizure kind of depending on how this presents okay so particularly in the right parietal and temporal lobes this can mimic this altered behavior now like I just mentioned this notion of delirium is very similar to encephalopathy but the technical definition is any diffuse disease of the brain that alters brain function or structure and the hallmark here is altered Mental Status but as I mentioned a minute ago this usually carries the connotation of underlying medical illness rather than the psychiatric element of the disease so this is where we get terms like hepatic encephalopathy or encephalopathy where thought to be from ammonia but from liver failure or uremic encephalopathy okay these are all medical illnesses but this really has largely been the turn determined by the icd-10 codes so the government and I think it's not as important clinically then we know the difference kkoma so that we know the technical definition here this is a state of persistent unresponsiveness this means the total absence of arousal and awareness now realize these folks may grimace to pain their limbs may demonstrate stereotyped withdrawal responses but they will have no localizing responses and no discrete defensive movements any movement that they have is reflexive so if we're going to call this the absence of arousal and aware what does that mean well arousal means wakefulness how awake is the patient basically is the light switch on upstairs and awareness basically means responsiveness to their environment can they interact with their environment or can they at least recognize that they can interact with their environment we may not see evidence of this as we'll see when we talked about locked-in syndrome but their brain should be aware that there is an environment around them that they can interact with a few more brain death brain death is simply the irreversible loss of all brainstem function this requires a fairly thorough neurological examination which we'll review at the end of this lecture a vegetative state is arousal without awareness the lights on but your brains not sure what to do with the information it's not processing the information and a persistent vegetative state is a vegetative state for greater than one month this duration was set because of some prognostic implications but it's important to remember this now I've just mentioned locked-in syndrome locked-in syndrome is usually because of a lesion at the base of the tegmentum of the mid pons this is usually a basilar artery problem and basically what it results in is complete paralysis with the exception of vertical eye movements so that arousal and awareness are intact but the patient can't communicate with their environment with the exception of vertical eye movements or sometimes blinking and this is often how these patients communicate akinetic mutism was a kind of severe Abe you Lea in which a patient has around arousal and awareness but no motivation so that's what a Bewdley a' means it's from the Greek term meaning lack of will so these patients have no slow responses if any to verbal stimuli but with sufficient stimulation they may have seemingly normal cognitive function this is typically secondary to bilateral frontal lobe disease and basically means that they will not voluntarily perform actions but with enough command and prodding they may engage in a physical exam this is a quick review of everything we've talked about so remember lack of arousal and awareness means coma if they have intact brainstem reflexes and brain death if there are no brainstem reflexes someone with locked-in syndrome will have complete arousal and awareness but a complete and ability to interact with that environment and then you have your deliriums and dementia and psychosis and vegetative states where a patient has arousal the lights on they're awake but they're not particularly aware to varying degrees of their environment now let's talk about the anatomy related to this this is not a neuroanatomy lecture so I think we just need basics but most basically in order to have arousal and awareness you need an intact reticular activating system which is demonstrated in grey and you need the function of bilateral cerebral hemispheres you can see here that arousal is dictated more by the reticular activating system in the brainstem this is sins to the thalamus the basal ganglia and as we'll see in a moment wraps down along the basal forebrain and then up and around into the cerebral hemispheres which brings about awareness and attentiveness and more executive functions ultimately the reticular activating system I would say is probably the most definitive region of your brain responsible for your level of consciousness so you can see here how all of the nuclei that are in charge of your arousal begin in or near the brainstem and basal forebrain several are up in the hypothalamus which regulates sleep and wakefulness these all move forwards into your forebrain and then wrap around distributing axons into the parietal lobes primarily for processing of information which creates awareness so basically your alert and the brainstem aware of your surroundings because of your bilateral cerebral cortices and you're motivated because of your frontal lobes what this means from a clinical perspective is that if someone is going to come in with a decreased level of consciousness from a an organic cause they have to have a lesion in one of these places okay either bilateral cerebral hemispheres the rostral pons or the diencephalon if they don't have a lesion in one of these places and you can imagine this probably comes with other concrete neural findings then they should have intact consciousness to some degree here are some examples of brain lesions that could cause coma the first in na and the top left is a diffused hemispheric damage bilateral hemispheric damage this is like a hypoxic ischemic encephalopathy someone who wasn't breathing and turned purple and didn't get any blood flow to their brain and realized that you have about five minutes without oxygen going to your brain before you start seeing a hypoxic and and also realized that some of these patients may return to fairly fairly normal neurological function only to subsequently deteriorate over time but this is a bilateral cerebral Hemisphere injury be in the top right demonstrates a diencephalic injury so a tumor and the hypothalamus for instance and remember the hypothalamus and part governs the sleep and wake cycles which can cause a decreased level of consciousness it can cause abnormalities in your sleep patterns see demonstrates damage to the para median upper midbrain so once again we're we're rostral to the the pons and we affect the the reticular activating system this is an example of the tip of the basilar embolus so an embolus that goes and lodges in the in the rostral portion the frontal portion of the of the basilar artery and it's also worth noting here because we'll talk about stroke in a later lecture that virtually any deficit due to injury of a discrete cortical area okay so what we would think of as our normal strokes can be mimicked by injury to the thalamic relay nucleus so if you go down to the thalamus you can create a stroke that looks just like a big MCA stroke or an AC a stroke remember also that because all these relay neurone nuclei are coming together you can have a fairly small area that has a lesion whether that's a stroke or that's a mass that can cause a bilateral injury which means it can caused a decreased level of consciousness and this is the most common finding in a tip of the basilar embolus in D and E you see a hype on Team injury so a basilar artery occlusion and then in a the pontine hemorrhage which often is something here is gonna cause compression of the surrounding brainstem so you really need to bleed with the surrounding edema and compression cause a decreased level of consciousness here here are some examples of lesions that didn't cause coma despite having profound neurological effects because they don't involve the ascending arousal system bilaterally so you can see that ace pairs the dorsal lateral pons on one side and it's pairs the para median midbrain so arousal here it is intact despite dense neurological deficits B is a lower pontine and medullary lesion and this spare is consciousness in general because this is really only the more call portions of the reticular activating system so it preserves the reticular activating system in the pons which is really more responsible for our level of arousal and what we seem to find is that a critical level for consciousness is somewhere in the rostral pons and here are some examples of lesions that cause a decreased level of consciousness and you can see that as you get down into the medulla there are several lesions particularly along the ventral surface here where we would expect the reticular activating to sit oh the reticular activating system to sit that cause a decreased level of consciousness but you see a lot more so up in the orange and the red and the pons that cause a decreased level of consciousness this is what the reticular activating system looks like you can see that it stretches right along the ventral surface of the cerebral aqueduct so this goes back to the picture that we just saw a moment ago here we're just on the ventral surface of that cerebral aqueduct or where we see damage causing a decreased level of consciousness and here you can see why this would happen so you can see the ascending reticular system as it courses just eventually to the cerebral aqueduct there and just eventually to the fourth ventricle also importantly to notice here I think pay attention to the structure surrounding this so you can see just near this reticular area there's the medial longitudinal fasciculus there are the vestibular nuclei there's the solitary nucleus as we go a little further north again you see the medial longitudinal fasciculus this is a very important Association you can see the abducens nucleus so you can you can imagine how any damage so the reticular activating system here is likely to result in abnormal eye movements because these sit right next door to each other moving a little further north again you can see the reticular nucleus they are just ventral to the cerebral aqueduct once again riding just alongside the medial longitudinal fasciculus you can see here the superior cerebellar peduncle once again right next door moving a little further north you can now see the trochlear nucleus once again we're seeing evidence of a close association between consciousness and the nuclei involved in eye movements so remember when we think about these things how closely tied caudally the the nuclei for dizziness and hearing are but remember we talked about how it's unusual for that to cause a complete alteration in level of consciousness unless there is a bleed and their subsequent pressure applied to the brainstem there but probably far more importantly is the close association of the circuitry involved in extra ocular movements regarding circulation to this area remember this is posterior circulation and as I've mentioned several times remember this is largely supplied directly from the basal er artery which makes sense of all these small little arteries around here okay that is the biggest one it's by no means a big artery but for this area it is the biggest artery and it makes sense an evolutionary perspective that you're going to supply the area associated with consciousness with one of the most durable arteries in the territory right so all the penetrating arteries that come off your supply this do remember that the AIC A&P ica can supply areas of this although these tend to be in the southern portions of the brain so the more caudal portions of the brain and remember that tip of the basilar artery embolus so you can see where that would affect you up at the rostral palms right there just before it branches off so for patients who have a decreased or altered level of consciousness what's your differential and how do you separate this out well most easily you can separate it into those who have trauma to their head which is a very simple workup and those who have no trauma to their head it's also worth splitting these folks into younger patients and older patients although that's a fairly subjective split no one would argue that a 90 year old and a 20 year old would have different causes where in the middle you draw that line is under some debate so to begin trauma what we're primarily looking for here are bleeds and here are several examples of several kinds of bleeds so you have subarachnoid hemorrhage as well as an epidural on the left and remember blood is white on an unannounced you can see blood of the ventricles on the bottom right this demonstrates the separation but in a non traumatic patient so you've got your non traumatic patient with focal signs without focal signs and then with mini jism arm images meninges inés the meningeal signs are the easiest of the bunch you either have subarachnoid hemorrhage or meningitis but you can see that there's a large list of possibilities for those without which includes things like encephalitis and meningitis and subarachnoid hemorrhage because those are not perfect findings they're not perfectly sensitive we're gonna go over the important ones so with focal findings clearly vascular is one of the more common that we tend to think of and this can include stroke vascular insufficiency so like a carotid artery thrombosis even if it's not complete and subarachnoid hemorrhage or bleed infection is another cause of focal findings so meningitis encephalitis or brain abscess can all cause an altered level of consciousness with vocal findings sometimes this is as in with an abscess because of direct pressure applied from the abscess and and local inflammation but sometimes this is because increased intracranial pressure okay and that can cause herniation of the contents of the of the cranial vault and as you can imagine with these this can apply pressure on primarily the reticular activating system which can decrease your level of consciousness tumors and masses can also do this and lastly something that is always worth remembering with an altered patient blood sugar this is one of the unusual causes of a systemic insult a metabolic insult that can cause focal findings is hypoglycemia low blood sugar these folks can look like a stroke and they can have a decreased level of consciousness and this can be resolved with d50 with focal without focal findings as you can imagine it's more commonly endocrine and metabolic causes so things like hypothyroidism which in this case is called mix edema coma sepsis so severe sepsis particularly at ICU patients can cause a kind of delirium once again infection can cause as you can imagine things like encephalitis or meningitis which typically span the entire brain can cause a decreased level of consciousness without focal findings and the other thing is posterior circulation stroke now as you can imagine this typically and classically will cause focal findings and the classic findings are going to be dizziness diplopia although many people won't complain of diplopia but you will uncover it on physical exam a change in their ability to swallow and speak and the kicker here is cross findings so one side of the face will be numb the other side of the body okay one side of the face will be weak and the other side of the body will be weak these people also often have headache and vomiting and as we talked about in the dizziness lecture these people can also have a Horner syndrome so remember the five DS of a posterior circulation stroke so dizziness diplopia this are threa or difficulty speaking dysphasia difficulty swallowing and dysmetria dysmetria difficulty with movements okay or ataxic movements this is an example of what you might see with a posterior circulation hemorrhagic stroke so on the top right well this actually says dim demonstrates a large pontine infarction okay but these can be bleeds as well and remember the pressure from the surrounding edema as well as bleeding into these and around these can cause pressure on the structures in in the brainstem that can cause a decreased level of consciousness as well as these other syndromes remember what sits down there so you can see the facial nerve sits down there the facial nucleus the medial lemniscus sits down there okay your cortical spinal tracts sit down there just underneath the basilar artery your vestibular nuclei tend to sit out laterally so they may be spared in this unless it's a large bleed or their significant edema primarily in these you're going to see an all are decreased level of consciousness and particularly you may see coma because of the facial nucleus and it's it's you're gonna get a unilateral facial weakness and because the abducens nucleus sits right there once again very nearby and it projects its nerve through this area you may see a lateral gaze palsy misdiagnosis in this condition can include locked-in syndrome remember that tip of the basilar artery embolus can cause a complete paralysis with the exception of vertical eye movements and without careful physical examination you may miss this remember Gyan beret syndromes so an ascending motor paralysis can ultimately present much like locked-in syndrome these people can eventually have complete motor paralysis and without EEG it can be difficult to determine the cause of their seeming coma severe Parkinson's and then also psychogenic unresponsiveness can also cause similar syndromes moving on to evaluation how do we evaluate patients who have a decreased level of consciousness well you use family you use friends you ask the EMS personnel police officers or caseworkers you find anybody that may be associated with the patient and try to get information because remember these patients if they're comatose won't talk at all if they have a decreased level of consciousness they may be confused particularly if you think about some of the reasons that caused this like meningitis and encephalitis when brain stem strokes or hypoxic injuries these patients may not be reliable in a previously young healthy individual with a sudden onset decreased level of consciousness you have to be thinking drug poisoning whether that's recreational drugs or overdose on medications a subarachnoid hemorrhage or be looking for signs of head trauma if it's a gradual onset change if they've gradually gotten worse over days or weeks and now they're beginning to have severe alterations in their level of consciousness thing metabolic if they had perimetry signs they had focal weakness so they were dragging an arm or leg or they had sensory complaints and this is not uncommon and prickly not uncommon to be missed when they complained they had tingling particularly unilateral tingling it's easy to disregard a young otherwise healthy appearing patient until they come in altered you need to think about a central cause complaints like diplopia or blurry vision once again particularly unilateral tend to portend a central cause something else worth remembering is pupillary pathways are the most resistant to metabolic insult so always check the pupils there are clearly some exceptions to this rules to this rule things like narcotics and anticholinergic swill caused classic changes in the pupils but in general metabolic insults don't affect the pupils central causes do in older patients near geriatrics you need to be thinking cerebral hemorrhage or infarction and remember with all those bridging veins they're more likely to have a subdural this can be slowly progressive so they can have how to fall weeks ago and have gradually developed a decreased level of consciousness over that time secondary to a subdural hemorrhage slowly compressing their brain they have more room for that to move as well they can have an infarction older folks may have an infarction so they may have a stroke that causes a decreased level of consciousness more in the sense of the delirium it causes any insult to a geriatrics system may cause a kind of delirium where they become confused and more difficult to arouse ok old folks don't necessarily follow the same rules that young folks - so anybody who's older with a decreased level of consciousness you need to do a great neuro examination and you really need to think about doing a CT of the brain to make sure they're not bleeding and physical exam you need to really check vital signs here that can give you clues in particular as to whether or not this is an endocrine or metabolic cause whether this is a drug overdose clearly you need to do a good neurological examination but there are really five parts of it that you need to do we'll talk about in a moment you need to try to do a good fun to scopic exam trying to rule out increased intracranial pressure by identifying papilledema or the lack thereof and then you want to do a good secondary exam looking for signs of trauma or other signs of infection signs of track marks to suggest IV drug use okay inner ear infection to suspect potentially a source causing something like meningitis right so the five key components of the neurological examination include clearly number one level of consciousness number two you're going to look at the pattern of breathing and basically at this point all you need to know is if it's not a normal pattern of breathing you need to be concerned about a central cause particularly if it's a if they have a decreased respiratory drive but there are certain classic patterns of breathing chance tokes breathing for instance that suggests a central cause of a decreased level of consciousness you always want to check the size of the activity of the pupils particularly if they are not breathing effectively and you're going to have to intubate them because if you're going to give them a paralytic you want to have an initial neurological examination at least the best you can do in a rush and knowing in their pupillary size are they equal are they reactive is incredibly helpful since they're going to be paralyzed particular if you're using something like rock you're owning a rocuronium or vecuronium that are longer-lasting paralytics you may not have a good neurological examination for an hour or two hours if they're alert enough you can try to tech detect spontaneous extraocular movements if not and you can clear their cervical spine you can try to test their ocular vestibular responses there oculocephalic response and then lastly there's get a skeletal motor responses you want to check their babinski's you want to check their DTRS you want to check their response to pain if they have a non focal neurological examination you need to be thinking about toxic or metabolic causes they did a trick a drug is this a Patek encephalopathy liver failure okay is this severe kidney failure is this an infectious cause like encephalitis okay or meningitis or is is this hypoxic ischemic which usually you'll get to the bottom of because they look like a smurf when they come in or they have a history of narcotic use or they're just hypoventilating if it's a focal neurological examination you need to think about an intracranial lesion like intracranial mass or tumor and your cranial shift caused by increased pressure from something a bleed in their head a bad stroke with edema from an evaluation standpoint CT brain in the acute phase is the most important test you do because it can at least give you a general idea about the structure of their brain are there are there large masses is it causing midline shift so is it pushing the brain over to one side which can potentially compress the brainstem is there evidence of a bleed okay as with most neurological complaints you need to check a finger stick blood sugar because as we discussed a low blood sugar can cause a decreased level of consciousness and it can cause a non focal exam or a focal exam that looks like a stroke and then because infection is so high on our list here you need to think about doing a lumbar puncture particularly clearly in an altered patient with a fever or somebody with a recent headache and vomiting treatment for the decreased level of consciousness patient so in the acute setting what are the basics manage the airway here because remember they may not be breathing effectively try to decide if they need fluids lots of these people do and establish your safety net get to IVs get them on the cardiac monitor even people with a subarachnoid hemorrhage actually have a higher risk of having dysrhythmias make sure you catch them so that you can treat them then from a medication standpoint the shotgun approach includes thiamine glucose and naloxone so what do these treat well thiamine protects against Wernicke's and stuff and Wernicke's encephalopathy is comes from b1 thiamine deficiency right and we typically see this in alcoholics or those who are malnourished whether that's hyperemesis gravidarum they're pregnant in the can't keep food down that they had a bariatric surgery or they're anorexic okay for whatever reason they're not getting their vitamins give them glucose check a finger stick first okay and then give glucose if you're concerned about Wernicke's encephalopathy give thiamine first and then the lock cylinder versus opiates so this is in particular for the decreased level of consciousness who is hypoventilating right who I'm concerned about and opiate overdose remember as a side note this is shorter acting than many opiates out there so that if you reverse this they may wake up only to later fall asleep again when the naloxone wears off but their opiates are still in their systems particularly with a large overdose because remember it can slow gut motility to review Wernicke's encephalopathy remember this is from thiamine deficiency so vitamin b1 this results in encephalopathy so altered or decreased mental status oculomotor dysfunction so funny looking eyes and eight axia a third of these are from alcohol the rest come from anorexic so they're simply not eating enough vitamins bariatric surgery because they can't absorb enough the chronically malnourished like hyperemesis the pregnant gals that can't eat dialysis patients because they can actually lose water-soluble vitamins and this is thought to contribute to some of the delirium associated with these folks and then systemic illnesses folks with sepsis because they have increased metabolic requirements and you have to keep up specifically what we can see clinically with these people is disorientation so we talked about delirium early these people can be disoriented usually first to time then to place and then to the people around them they can be indifferent to their environment this is much more common in severe illnesses and they can be inattentive oculomotor front dysfunction can spam from nystagmus to a lateral rectus palsy and remember we can see this in an brainstem stroke to conjugate gays palsies and then they can have a taxi on remember hypoglycemia may present with altered Mental Status decreased level of consciousness and focal neurological deficits if you're concerned about Wernicke's which we once again don't tend to see as often anymore but if they've got risk factors give thiamine first it's cheap it's easy and it could protect their brain the other note here is if you have a patient who is hypoglycemic particularly severe enough to cause these problems start asking why are they hypoglycemic did they overdose on something like glyburide so supplying urea did they take too much insulin was this an accident was it intentional is there a severe illness going on that caused their blood sugar to drop right ask questions the opiate problem has been in the news a lot lately if anybody's seen this story this was a husband and wife who had gotten narked out of their minds they were swerving all over a road a police officer pulled him over and their son was buckled in the backseat and they passed out pretty much immediately I'm parking the car this is a big deal and we're seeing a lot more heroin now that the government's making it harder to distribute prescription opiates and these can be really bad overdoses particularly because a lot of people who get them don't actually know what they're taking and there's you know fentanyl and sufentanil and all these other synthetic opiates that sometimes have significantly more potent effects than heroin so remember opiate overdoses are reversed with narcan or naloxone we're starting to actually see this as a this is can be given I am it can be given intranasally increasingly okay remember it doesn't last as long as several of these medications so they may become unresponsive and need multiple doses now moving on the Glasgow Coma Scale this is important this was originally created by traumatology trauma surgeons to assess people with head injuries it has been used in non trauma patients since then because it provides kind of agreed upon way to assess people with the decreased level of consciousness but realize it doesn't hold the same significance in the non trauma patients other than giving us a way to talk about them there's a scale called the AVP you say at scale which stands for alertness verbal response pain response and unresponsive which is just about as good as this and basically you just say they're alert they're responsive to verbal stimuli painful stimuli or unresponsive but this is classically used you're gonna see this throughout your career it hasn't changed since it was created and so it's important you know it there are three elements to the GCS there is a opening there is verbal response and there is motor response i opening includes four factors either they spontaneously open their eyes they open their eyes when you tell them to when you hurt them bad enough or not at all if they open them not at all they still get one point just for participating so remember that the verbal response this includes are they coherent are they confused are they using inappropriate words but fluent are the incomprehensible so moaning and making sounds or are they not talking at all coherent is pretty self-explanatory confused means they're still fluent but they may be disoriented they may not know where they are or who they're with okay inappropriate words it's kind of like Lewis Carroll's Jabberwocky so twas brillig and the slit Toves did gyre and gimble in the wave like inappropriate words theologians okay this is a three two is incomprehensible speech sorry for the political little joke I thought it was too good to pass up and one is nothing they're not talking they're not making sounds moaning gets you too no sound gets you one lastly motor response gives you six so you get four points for a perfect i opening you get five points for your verbal response and you get six points for your best motor response if you can follow commands so if you're moving spontaneously and a meaningful way if you can't do that but you can localize the pain you get five and if you think about it that makes good sense because your body has to process the information of where you hurt to direct a hand to go to the painful spot that's a complicated movement it makes sense that that would get you the next most points if you can't do that we're now getting into reflexive behavior right if you touch something hot you reflexively draw away from it to protect yourself that is a protective brainstem function so you may see that in a comatose patient but not a brain-dead patient that gets you 4 4 3 & 2 these are commonly confused so how do you tell the difference between decorticate and the cerebrate positioning well decorticate involves flexion of the arms the cerebrate involves extension of the arms so you get three four decorticate and two four de cerebrate posturing I do realize that the leg the leg movements here are extension for both there's something called a triple flexion response it's a spinal cord mediated movement and that's something different to kind of help you remember to quartic it and de serra de Britt will do a quick history lesson so the creators of the Glasgow Coma Scale which makes sense from Glasgow in Scotland found that head-injured Scottish drunks with decorticate posturing recovered about a third of the time whereas the dis cerebral drunks only recovered a tenth of the time leave it up to the Scots to come up with an injury score based on drunks falling down but what this can help you remember is for the pugnacious Scots if you think about the the fighting position the guy that's left standing with his arms flexed is in better shape than the guy he just knocked out with his arms extended okay so the guy with his arms flexed gets three the guy with his arms extended okay Dussehra Britt gets it too and the guy that doesn't move at all gets a one so here's your four four eye movement your five four verbal response and your six four your movement to review this table does not open its eyes and so it gets one for eye opening it does not respond to you so it gets a one on the verbal score and it does not move and so it gets a one for best movement that gives this table a GCS of 3 for practice on a patient the patient's eyes open to pain so it gets they get one for nothing and two for pain correct so they get to they're speaking incoherently so one for none two for incoherent gives them two for their verbal response and may withdraw so remember this is reflexive you get one for no movement two for Dussehra Britt when you extend because you've just got knocked out three for decorticate because you're still standing with your arms flexed and four because you withdraw okay so you get four for motor response this gives you a GCS of 8 which is an important number because in trauma in the trauma world they say a GCS of 8 means intubate so eight or less means you intubate because this is a critically injured person who is unlikely to protect their airway realize this does not translate into the medical world there are plenty of people who get so drunk they have a GCS of less than eight and are still protecting their own airway and a lot of endocrine emergencies people can still protect their airway with a lower level of consciousness but in the trauma world this gives you a good rule of thumb and an incidentally it rhymes now let's get into some brainstem reflexes because this is when we're really starting to evaluate this severely decreased level of consciousness patient okay this is part of the brain death exam as well you're trying to rule out any brain stem reflexes so the vestibulo-ocular reflex now we've talked about this in the dizziness lecture as a function of the hit the head impulse exam or the head impulse test in an awakened alert patient this is the circuitry that you're evaluating but in the comatose patient you're going to use cold calorics to evaluate the same because they can't spontaneously look at you so what you're going to do is you're gonna squirt cold water into a patient's ear and in an unconscious patient they're going to look towards the affected ear now realize in a patient with an intact vestibular nucleus they will look towards the ear there will be no corrective saccade they'll be known as Stagg miss they will simply look towards that ear if the reflex is intact you will see them slowly look towards the ear and then their eyes will try to snap back towards midline and this is just like we talked about with the head impulse test what you can imagine some annoying person is sitting next to you or in this case my adorable son he squirts water in your ear and you slowly look towards that ear because the cold water slows down the movement in the it slows down the resting tone from that ear the signal that it's sending to your brainstem which makes you think that your head is turning that way your eyes slowly moves towards that side and then snaps back to midline when your reflex overcomes that stimulus remember that it's named for the direction of the fast component so in this case would be a leftward nystagmus but it's caused by a problem on the right I'm squirting cold water into your right ear the other reflex we check to evaluate brainstem function is called the oculocephalic reflex and remember we talked about the hortence of the eyes because of the nearness to the reticular activating system and this takes advantage of the neurons projecting into the cervical spine to help you fix your eyes on an object when you're moving your head when you're rotating your head and flexing and extending in an intact reflex okay so the brainstem is intact the eyes should stay put on the examiner if you're staying in front of standing in front of them okay the eyes should move in their head so when you moved when you rotate the patient's head to the right their eyes will move left when you rotate their head left their eyes will move right if you wrote if you extend their head their eyes will move down if you flex their head their eyes will move up they will stay fixed like a doll's eyes this suggests that the reflex is intact and they have an intact brainstem function the cause of their decreased level of consciousness is not because of brainstem death if their eyes stay fixed in their face like they're painted on that means this reflex is not intact and there is a brainstem problem regarding outcomes what helps you prognosticate in a patient with a decreased level of consciousness well for one decorticate positioning or posturing is a bad sign okay this suggests significant brain damage particularly down in the brainstem myoclonic jerks so these are the quick rapid jerks and in the muscles that you'll see sometimes tend to have a bad prognosis and fixed and dilated pupils are a very bad prognosis now you have to rule out ingestion because once again there are certain medications there are certain overdoses that can cause this so like an anticholinergic syndrome typically these people have a syndrome that you can figure out what's going on otherwise fixed and dilated pupils in the absence of some other syndrome is a bad prognosis so declaration of brain death for those of you who will work in ICUs or on the floor and have to do these exams remember brain death is the irreversible cessation of all brain functions including the brain stem so including things like the vestibular ocular reflex including the oculocephalic reflex and we talked about why that's important because they run right next to the reticular activating system usually if one is damaged they are both damaged this has to be an irreversible coma with loss of all brainstem reflexes because remember coma does not necessarily mean loss of brainstem reflexes and you have to have an absent respiratory drive which means if I disconnect you from the ventilator and I wait for the carbon dioxide to build up to give itself a chance to initiate any breathing you still don't breathe now remember you can't have a paralyzed patient here they have to be able to breathe on their own so you have to let paralytics wear off if they're on paralytics so non paralyzed patient co2 builds up that's one of the most potent respiratory stimuluses we have and they still don't breathe also remember you have to correct for all these things so we're severe electrolyte imbalances acid-base disorders if you can hypothermia so make sure you warm the patient hypoglycemia we've talked about this again and again and again always check blood sugar hypotension and drug intoxication now if left long enough a brain-dead patient will eventually develop these and they become increasingly hard to resuscitate and this may be unavoidable but in an otherwise stable patient you want to correct for all these last thing I want to mention something called the Lazarus sign some people are unaware of this but after a patient has died and when we tend to see this is when we've completed a we stopped working a code either for medical futility or because we've done a bedside ultrasound their hearts just not beating anymore for whatever reason they've died and a few minutes afterwards there's this process where the arms abduct a B duct or the shoulders a B duct and the arms flex much like a zombie in fact and this is called the Lazarus sign this is thought to be secondary to hypoxia and basically dying brain cells this does not indicate and intact anything that brain is still dead this is neurons dying but it can it can scare families and it can scare physicians if you've never seen this before so it's it's worth knowing it's also worth remembering when you have family come in either to have them wait or just be around to address this so that's the end of this hopefully this was helpful as always please let me know if you have any questions and until next time

Channel: James Herrington

Views: 13,172

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Id: wb62W6wAvRQ

Length: 51min 46sec (3106 seconds)

Published: Thu Sep 21 2017