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Common stroke signs and symptoms

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Vishal Punwani.

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Video transcript

- [Voiceover] You can develop all sorts of symptoms after having a stroke because if something's happened to your master control center, your brain, then all sorts of stuff, all sorts of functions can be compromised and that will manifest as you having symptoms, right? That makes sense. But there are certain groups of symptoms that happen the most frequently and I want to take a look at these. These happen the most because, well, remember strokes happen when blood flow is compromised, right? These groups of symptoms are the result of common blockages in certain arteries. And we'll explore this. The first one we'll look at is sudden numbness or weakness of the face, the arm or the leg. Immediately, a few questions pop into your mind, right? Why would you develop numbness or weakness? Why commonly the face, the arm and the leg? Also, does this happen on both sides of the body or is it just one side of the body? These are all great questions. Oh, thank you. Let's look at each one in turn for some possible reasons. Why would you develop numbness or weakness? The numbness might happen if you developed a stroke in this area here called the Primary Somatosensory cortex, right? As its name implies, it's the key part of your brain that allows you to feel stuff so if it gets damaged, you might end up with a change in your sensation. For example, numbness. The weakness could happen if you developed a stroke next door, in this Motor cortex area here, right? Again, the name, kind of, lets you know it's a major player in controlling your movements. Damage could result in weakness of your movements. Let me just clarify that it's a little bit more complicated than just the Sensory cortex is in charge of your sensation and your Motor cortex is in charge of your movements, there's a lot more bits of your brain that have inputs to all these things but we won't worry about those for now because I just want to focus on some of the concepts here. Now, why the face, the arm, the leg, why? Why different parts of the body? The short answer is that it depends on which part of the Motor or the Sensory cortex gets damaged. Let me put it to you this way, the different parts of the body are, sort of, represented on the Motor and Sensory cortices in different places. This isn't perfect but conceptually a common way to think of it is as this guy, sort of, draped over, right? through a line down on the brain with his legs dangling in the longitudinal fissure and his arms, sort of, about here and his face down here. It turns out that the neurons in roughly this area supply the Motor and Sensory for the legs and neurons in roughly this area supply Motor and Sensory for your body. The ones in this area here control the bulk of your upper limbs and then these ones here, for your face. You might, actually, notice that the lips and the face and the hands aren't proportional to the rest of the body here. That's because more sensitive parts of the body, like your lips and your face and your hands, they get dibs on more neurons to supply them so this is usually drawn to reflect that. You can probably see where I'm going with this but if you get some compromise of your end to your cerebral artery, your ACA, which supplies this part of your brain here, you'd get possible Motor or Sensory symptoms in your legs. If you get some compromise of your Middle Cerebral Artery, your MCA, which supplies all of this area here, you'd end up with symptoms affecting your face and your upper limbs, right? Finally, one or both sides of the body. Most of the brain is setup in this interesting way where, and actually we'll go into details, but it's setup so that this Motor and Sensory cortex on say the left side, are controlling and interpreting sensations for the opposite, the right side of the body and vice versa. That just has to do with the way that their neurons are connected up to send and receive signals. The neurons, actually, cross from one side of the body to the other. That happens either in the spinal cord, in the brainstem or in the brain itself. You get this crossing over. But I digress. If you have damage to one side, you'd end up with symptoms on the opposite side. If you have damage to both sides, then you get symptoms on both sides of the body, savvy? I just watched 11 hours of Pirates of the Caribbean so I might use pirate speak a lot, savvy? All right, so that's one major set of symptoms, sensory changes or weakness. What's next? Sudden trouble speaking or understanding others. Why would this happen? The most common reason you might have trouble with your speech is that the stroke has affected some of the key parts of your brain that deal with your speech which are served by the Middle Cerebral Artery. Actually, almost 40% of people who have a stroke end up with some problems with expression of their language. Let me give you an example here of two important areas. You got his area of the brain here in your frontal lobe called your Broca's area which is involved in nice, fluid speech productions. If this gets damaged, you might end up with, sort of, slow and poorly articulated speech. You've got this area right here near the junction of your temporal and parietal lobes called your Wernicke's area which is important in your ability to understand what people say to you. It's, actually, also really important in producing nice, meaningful, specific speech so if you damaged this area, you'd end up with poor comprehension of what people are saying to you and when you speak, you wouldn't really be able to pick the right words to express what you want to say. You, kind of, just end up rambling a bit, unfortunately. Next up, we have sudden trouble seeing in one or both eyes. Here's a top-down view of the brain to help us understand this. Up here is the front and back here is the back. This is the left eye and this is the right eye. There's really two, sort of, overarching parts to proper vision. You need a healthy set of eyes, to bring in the visual information, and you need a healthy brain to process and interpret that information, right? If you had some stroke-related damage to one of the parts of the brain that manage your vision, right? let's say you had a blockage in your Posterior Cerebral Artery, your PCA, which supplies your occipital lobe, that's the major lobe that allows you to have vision, you could, actually, end up with some vision loss. The occipital lobe is also wired up in an interesting way where... Actually, let me just draw out the two fields of vision to make this really clear. Here's your left field of vision from your left eye and here's your right field of vision from your right eye. If you sustain some damage to this left side of the occipital lobe, you, actually, end up with loss of vision in the right halves of both your left and your right visual fields. That's weird, right? That just has to do with the way your neurons are connected up from your eyes to your occipital lobe. Similarly, if you have a stroke affecting your right side of your occipital lobe then you'd lose vision in both your left visual fields, right? Very interesting. All right, what's next? Another common set of symptoms are ones to do with balance. You get this sudden feeling of dizziness or loss of balance or coordination. You might have trouble, say walking. This can happen if you have a stroke in your Cerebellum. A substantial enough blockage in at least one of the three main arteries that supply it with blood. Why would this result in dizziness or loss of balance? Well, because the Cerebellum is the major coordinator of our movements, if something happens to it, we start to get imprecise and uncoordinated and we end up having poor timing to out movements. Okay, so the last symptom I'll cover is just a sudden severe headache with no known cause, no cause that you can, sort of, think of. You might remember that there's a subtype of stroke called the Hemorrhagic stroke which is where a blood vessel in the brain, actually, bursts and causes a stroke by loss of blood from the cerebral circulation. This is probably not so surprising but when a blood vessel bursts in your head, it hurts a lot. You get a sudden severe headache with no explanation. There you go, those were five of the most common stroke signs and symptoms.