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Course: Health and medicine > Unit 8
Lesson 11: Multiple sclerosisMultiple sclerosis signs and symptoms
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Want to join the conversation?
- But arent the symptoms kinda normal? i mean generally v all have numbnesss or difficulty in making certain decisions . so how do v actually know we hv MS?(2 votes)
- We would need to take a couple of tests on the patient, such as a nerve conduction test to test the strength of the action potentials, and the rate of axonal conduction. A slower rate of axonal conduction than normal would indicate defective myelin sheaths.(10 votes)
- What determines where lesions occur? Is there anyway to predict it?(3 votes)
- You can't predict it with out a MRI scan on the brain(3 votes)
- what is the most common area of lesions and what is the most common symptoms of MS?(3 votes)
- There really isn't a most common area. Lesions occur sporadically in the brain parenchyma and look like whitish clusters on an MRI.(3 votes)
- at 6.10 the sensory neuron is drawn to enter the spinal cord anteriorly, doesn't the sensory neuron enter the spinal cord dorsally?(1 vote)
- I see the confusion. Your thinking that the sensory neuron enters the spinal cord anteriorly seems to be based on the posterior view of the brain. But if you look carefully, you can notice that the spinal cord faces anteriorly based on the anterior location of the ventral median fissure. Therefore, the sensory neuron enters the spinal cord dorsally, the correct way. There would be no confusion if the brain had been rotated 180 degrees around.(1 vote)
- 為何多發性硬化會使其肌肉收縮?(1 vote)
Video transcript
- [Voiceover] Here we
have the brain of someone who's suffering from multiple sclerosis. You'll notice that there
are these bright spots that are found located
throughout the brain, known as plaques. These plaques are also
referred to as lesions. A lesion is really just a
piece of damaged tissue. Now, note how these plaques are forming in different parts of the brain, so the really important
thing to keep in mind, is that different parts of
the brain will be responsible for different functions. Some parts may be involved
in vision, movement, touch, cognition, and even emotion, so you can get a dysfunction
in each of these categories, depending on where the lesion formed. For example, if you have
a lesion that forms in parts that are responsible
for vision, or for seeing, then you won't really
be able to see as well. As it turns out, visual
symptoms are actually among the first symptoms that people
usually experience in MS, so I'm gonna be talking about those first. I'm gonna show you here
a picture of the eye. At the back of the eye, you
have this structure over here, called the optic nerve. The optic really just carries
all the visual information picked up from the eye,
to the rest of the brain. As it turns out, it's
actually a pretty common site for lesion formation, so
let's say we have a lesion that, you know, maybe
it forms around here. If you get lesions in the optic
nerve, then you can imagine that there will be a lot of
problems with the vision. It's not as severe as total
blindness, but, in general, your vision is impaired. Let's say you go to the eye doctor. They're gonna ask you to
read off a series of letters on a screen, across the board. Your ability to read off
of the smallest letters will be pretty badly impaired. You won't really be able to see these letters as well anymore. In addition to that, colors also appear a little bit washed out, so, let's say, you have normal, healthy color vision. You're looking at this green
box and it looks like this, but, if you have multiple
sclerosis, the green box may actually look a little
bit more washed out, so, maybe, something like this. It's not as clear, or not
as distinct, I should say. In addition to this impaired vision and this washed-out color vision, people will also just
experience general pain, cuz whenever they move their eyes around, it kinda hurts a little bit. Those are some of the major
visual symptoms that people feel when they get lesions in the optic nerve, but there are other parts of the brain where, if you get lesions there, then people may experience
other visual problems as well. I have this green nerve
coming out from somewhere, and it's innervating
the muscles of the eye, so this nerve will be responsible
for moving the eye around. Where does that nerve come from? It comes from a part of the
brain known as the brain stem. Really, there are more
nerves that come out, but this is just to simplify
our understanding of it. Now, in the brain stem,
you have these cell bodies. These cell bodies are
gonna project their axons into these nerves, then these nerves will, ultimately, innervate
the muscles of the eye. As it turns out, this is
actually a pretty common site of lesion formation, this
general area of the brain stem, or, at least, where the axons are in that region of the brain stem, so you can imagine that
you'll get a lot of problems with moving your eye around. If you ever look at the
eyes of a person with MS, what you'll notice is that they look like they're vibrating a
little bit, so, sometimes, they may have a vibration
motion horizontally, or, even vertically, as well. In addition to that, if you show a yellow bar of light maybe, it could be any image,
but let's say we have a yellow bar of light, if you show this, they may report seeing kind of
a second yellow bar of light right next to it, so they're experiencing this double-vision effect. The reason is because, well, their eyes aren't really moving in unison anymore. Because they're not moving
in a coordinated fashion, they're not really able to converge those images that they
receive, so, because of that, you see this double-vision,
you see two of one object. The brain stem isn't really
just gonna innervate the eye, it can innervate other
parts of the body as well. Let me clear up some space here. As it turns out, the brain
stem also is gonna innervate a part of the body, something
known as your throat. You have a whole bunch of
muscles in your throat, and the muscles in your
throat are gonna be doing a whole bunch of different things. Some really important
functions would just be talking and swallowing food, so if you get lesions in the brain stem, maybe you have some lesions
that form over here, then you can have
problems doing just that. A lot of people with MS, maybe they may stutter a little bit, they may not really talk
as well as they used to. They may also have difficulty
in swallowing their food. It becomes much more painful
and much more difficult to do just that. Now, I wanna show you symptoms that are associated with lesions in another part of the
central nervous system. Let me actually just clear up a little bit of space here again. Now, I'm showing you
the picture of a brain of someone who's kinda facing towards you. Down here, we have a
picture of the spinal cord, and this is really just a
segment of that spinal cord. The spinal cord is gonna be responsible for connecting the brain
with the rest of the body, so it transmits information
about both touch and motor control between the brain and the rest of the body. Let's say you have some kind of nerve fiber ending over here. This nerve fiber ending is, basically, gonna transmit the information about touch to the spinal cord. Then, from the spinal cord, that information is just gonna be taken up to the rest of the brain, so, maybe, you have some more nerves that
go up from the spinal cord, and, then, into the brain. Then here, it's just later processed. Of course, this is a very
simplified schematic, but, in general, if you
get lesions in this area, maybe you get some kind
of lesion over here, or maybe one over here, then you can get a lot
of problems with touch. One pretty common symptom that people might feel is numbness. In addition to that, people
may have the sensation of pins and needles
prickling into their skin. This is really just the equivalent of your limbs falling asleep. We typically call this paresthesia. Finally, people may just
experience plain old pain. cuz sometimes if you look
down or you look forward, then the person may
kinda feel the sensation of like an electric shock,
moving down their spinal cord, then radiating into the
rest of their limbs, so it's not just touch
information that's transmitted between the body and the brain,
it's also motor information. Motor information can
move down from the brain into the spinal cord. Then, from the spinal
cord, that information can contact another set of nerves that'll innervate the
muscles of your hand. If you get lesions in these areas, you're gonna get some
problems with motor control. For example, a lot of people
may experience paralysis. They may not be able to use
their legs to move around, so that renders a lot of
people incapable of walking, so they need to use wheelchairs
and canes to move around. On the flip side of paralysis, they may experience spasticity. In spasticity, their
muscles are too stiff, they're too overactive, and,
because they're too stiff, they become very tense. It's as if the muscles are
just constantly contracting for some reason, and because
they're constantly contracting, this can lead to quite a bit
of pain in those muscles. In addition to that,
people may also experience problems with bladder and bowel controls. Maybe they're urinating too frequently or maybe they're finding
difficulty in urinating where there's a problem in
the control of the bladder, and there's also a
problem with the control of the bowel movements. Then, finally, people may
experience sexual dysfunction. Oftentimes, a lot of people
will have problems in initiating or maintaining arousal. They may also have problems
in achieving an orgasm. Next, let's turn this
brain around and let's talk a little bit more about some
of the cognitive symptoms that people experience in MS. Now our brain is kinda
looking to the right, and you'll see that I've already shaded in a part of the brain, and
this part of the brain is simply known as the frontal lobe. What does the frontal lobe do? Well, it's responsible for cognition. What are some cognitive behaviors? Well, there's attention, working memory, thinking, and decision making. If you get lesions in the frontal lobe, then you can experience a lot of problems in all these cognitive functions. For example, a lot of people
may experience problems with paying attention to things. They may also be a little
bit more forgetful. They may have problems thinking about and understanding certain
concepts, and, subsequently, their ability to solve problems
is pretty heavily impaired. Finally, they may also be a
little bit indecisive as well.