Help me with Nystagmus (COWS)

[Ihateverbal]

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Warm water instilled into left ear while patient is supine elicitis nystagmus with quick phase to LEFT. Warm Water instilled into right ear elicitis no eye movements. Which of the following is the most likely site of a lesion.

E) Left veistubular apparatus
F) Right vestibular apparatus

Just to make sure I’m not completely out of the ball park, the answer would be F right?

 

[psychforme]

Of course. The right vestibular apparatus is in the right ear and it sends no signals as there is no reaction to the water test. The brain stem has gotten used to the lack of signaling from the RVA and is compensating.

 

[stickshift]

Forget the COWS mnemonic. It's confusing and inaccurate.

 

[psychforme]

And it is not applicable in this case.

 

[ENThopeful]

Forget the COWS mnemonic. It's confusing and inaccurate.

i think its an unwritten rule that the COWS mneumonic describes the fast nystagmus and not the slow one that readjusts

took me a good few years to figure that one out and im still not sure that its right

 

[psychforme]

took me a good few years to figure that one out and im still not sure that its right

How long have you been studying pre-clinical medicine 😕

 

[ENThopeful]

haha i just so happened to learn it in undergrad too.. had a teacher who liked throwing clinical stuff out there

 

[OveractiveBrain]

COWS is an annoying mnemonic, since you have to understand a whole lot just to use it.


What you are testing is cranial nerve 8. In some one who is awake, you test this by having them look at the ceiling at a fix point while you rotate their head. If their eyes stay fixed, they have intact cranial nerve 8. If their eyes move with your movements of their head ("Dolls Eyes") their cranial nerve 8 is broken.

COWS is used to assess some one who is unresponsive. It tells us two things. First, it tells us if the cranial nerve is intact. If there is a slow component towards the lesion then the cranial nerve is intact. Secondly, it tells us if the cortex is intact. If there is a fast component away from lesion then the cortex is intact. If there is no movement at all, then the cranial nerve itself is lesioned.

Lets handle the CO of cows. You inject cold water into an ear. You inject cold water onto a cranial nerve. Now, cold water makes things cold. Cold water makes things not work. So, with cold water, you induce a cranial nerve 8 lesion. That means, if the cranial nerve is intact, there is a slow movement towards the side you squirted water in. If the cortex is intact, there will be a fast movement away (following the slow towards) from the side you injected the water in. If the cortex is not intact, but the cranial nerve is, there is only a slow towards, and no away. If there is cortex, but no cranial nerve, then nothing happens.

Lets handle the WS of cows. This is harder to understand. Lets say that you have two normally functioning cranial nerve 8. By adding warm water you increase the activity of the side you squirted the water into. Warm water makes things work better. This means, relative to the side you stimulated, the opposite side represents the induced "lesion." If you followed the CO example well, you know exactly what happens. There is a slow component towards the lesion (which means away from the warm water injection) then a rapid component away from the lesion (which means towards the warm water injection).

So "COWS" actually referrs to the direction of eye movement during the fast away-from-the-lesion component following the slolw-towards-the-lesion component in someone who has an intact cranial nerve 8 and intact cortex. See why that is a confusing (and somewhat useless) mnemonic?

If you really want to take something away from COWS, and dont care to reread (or understand) my response, take this. COWS represents the direction of the rapid eye movement relative to the injected water; a cold water injection has a fast component opposite the injection while a warm water injection has a fast component that is to the same side as the injection

 

[Ihateverbal]

Got it!

 

[Knicks]

COWS is an annoying mnemonic, since you have to understand a whole lot just to use it.


What you are testing is cranial nerve 8. In some one who is awake, you test this by having them look at the ceiling at a fix point while you rotate their head. If their eyes stay fixed, they have intact cranial nerve 8. If their eyes move with your movements of their head ("Dolls Eyes") their cranial nerve 8 is broken.

COWS is used to assess some one who is unresponsive. It tells us two things. First, it tells us if the cranial nerve is intact. If there is a slow component towards the lesion then the cranial nerve is intact. Secondly, it tells us if the cortex is intact. If there is a fast component away from lesion then the cortex is intact. If there is no movement at all, then the cranial nerve itself is lesioned.

Lets handle the CO of cows. You inject cold water into an ear. You inject cold water onto a cranial nerve. Now, cold water makes things cold. Cold water makes things not work. So, with cold water, you induce a cranial nerve 8 lesion. That means, if the cranial nerve is intact, there is a slow movement towards the side you squirted water in. If the cortex is intact, there will be a fast movement away (following the slow towards) from the side you injected the water in. If the cortex is not intact, but the cranial nerve is, there is only a slow towards, and no away. If there is cortex, but no cranial nerve, then nothing happens.

Lets handle the WS of cows. This is harder to understand. Lets say that you have two normally functioning cranial nerve 8. By adding warm water you increase the activity of the side you squirted the water into. Warm water makes things work better. This means, relative to the side you stimulated, the opposite side represents the induced "lesion." If you followed the CO example well, you know exactly what happens. There is a slow component towards the lesion (which means away from the warm water injection) then a rapid component away from the lesion (which means towards the warm water injection).

So "COWS" actually referrs to the direction of eye movement during the fast away-from-the-lesion component following the slolw-towards-the-lesion component in someone who has an intact cranial nerve 8 and intact cortex. See why that is a confusing (and somewhat useless) mnemonic?

If you really want to take something away from COWS, and dont care to reread (or understand) my response, take this. COWS represents the direction of the rapid eye movement relative to the injected water; a cold water injection has a fast component opposite the injection while a warm water injection has a fast component that is to the same side as the injection

Even though I already knew this (no show-off), I just gotta say that THAT was the best explanation I've ever read about COWS.
👍

 

[neil100]

Warm water instilled into left ear while patient is supine elicitis nystagmus with quick phase to LEFT. Warm Water instilled into right ear elicitis no eye movements. Which of the following is the most likely site of a lesion.

E) Left veistubular apparatus
F) Right vestibular apparatus

Just to make sure I’m not completely out of the ball park, the answer would be F right?

Well duh man! Seriously. I am technically a pre-med but I even knew that. I am not trying to be condescending or what not. You know sometimes it is just better to step back from the narrow space that you are in and look at things in a general way. This helps out a lot in critical thinking scientific exams. Trust me. It really does.

 

[dbth77]

Well duh man! Seriously. I am technically a pre-med but I even knew that. I am not trying to be condescending or what not. You know sometimes it is just better to step back from the narrow space that you are in and look at things in a general way. This helps out a lot in critical thinking scientific exams. Trust me. It really does.

you sound like a huge douche. however, i'm not trying to be condescending or what not

 

[Captopril]

COWS is an annoying mnemonic, since you have to understand a whole lot just to use it.


What you are testing is cranial nerve 8. In some one who is awake, you test this by having them look at the ceiling at a fix point while you rotate their head. If their eyes stay fixed, they have intact cranial nerve 8. If their eyes move with your movements of their head ("Dolls Eyes") their cranial nerve 8 is broken.

COWS is used to assess some one who is unresponsive. It tells us two things. First, it tells us if the cranial nerve is intact. If there is a slow component towards the lesion then the cranial nerve is intact. Secondly, it tells us if the cortex is intact. If there is a fast component away from lesion then the cortex is intact. If there is no movement at all, then the cranial nerve itself is lesioned.

Lets handle the CO of cows. You inject cold water into an ear. You inject cold water onto a cranial nerve. Now, cold water makes things cold. Cold water makes things not work. So, with cold water, you induce a cranial nerve 8 lesion. That means, if the cranial nerve is intact, there is a slow movement towards the side you squirted water in. If the cortex is intact, there will be a fast movement away (following the slow towards) from the side you injected the water in. If the cortex is not intact, but the cranial nerve is, there is only a slow towards, and no away. If there is cortex, but no cranial nerve, then nothing happens.

Lets handle the WS of cows. This is harder to understand. Lets say that you have two normally functioning cranial nerve 8. By adding warm water you increase the activity of the side you squirted the water into. Warm water makes things work better. This means, relative to the side you stimulated, the opposite side represents the induced "lesion." If you followed the CO example well, you know exactly what happens. There is a slow component towards the lesion (which means away from the warm water injection) then a rapid component away from the lesion (which means towards the warm water injection).

So "COWS" actually referrs to the direction of eye movement during the fast away-from-the-lesion component following the slolw-towards-the-lesion component in someone who has an intact cranial nerve 8 and intact cortex. See why that is a confusing (and somewhat useless) mnemonic?

If you really want to take something away from COWS, and dont care to reread (or understand) my response, take this. COWS represents the direction of the rapid eye movement relative to the injected water; a cold water injection has a fast component opposite the injection while a warm water injection has a fast component that is to the same side as the injection

you, sir, are awesome.👍

 

[Captopril]

Warm water instilled into left ear while patient is supine elicitis nystagmus with quick phase to LEFT. Warm Water instilled into right ear elicitis no eye movements. Which of the following is the most likely site of a lesion.

E) Left veistubular apparatus
F) Right vestibular apparatus

Just to make sure I’m not completely out of the ball park, the answer would be F right?

I feel like there are alot of questions on UW where they make it seem complicated, and give a lot of answer choices to make you think that it is an extremely difficult question and you should just guess and move on. This would appear to be one of those (esp. if the answer choices go down to F). The thing with these is, most of the time some common sense can get you out of a jam pretty quick.

UW wants you to sit there and reason out COWS and then freak out when you've spent 2 minutes doing it and just guess an answer. But if you use the following concept, this question should take about 6 seconds:

If you are physically stimulating something, and it is providing absolutely no response, that thing is messed up.

So in this case, you are stimulating the right side's CNVIII, and gettin nothing back. Therefore, CNVIII on the right is jacked.

Of course, you should probably learn COWS anyway just in case, but just know that UW (and I assume USMLE) will never give you something that can't be solved instantly with a little background knowledge and some common sense.

 

[nadk9f]

http://en.wikipedia.org/wiki/Caloric_reflex_test

Is wikipedia wrong? It seems like whoever edited it wrote that the fast phase is to the same side with cold water, and vice versa for warm water.

Thanks

 

[JaySten]

Thanks OveractiveBrain, my professor was absolutely useless at explaining that the "same" and "opposite" part of the mnemonic pertained to the fast component, rendering me very confused.

 

[georgeissa7]

Conventionally, Nystagmus direction is considered to be the fast component direction.

COWS does work fine.