Caloric Testing Explained

caloric testing for medical students
USMLE, NBME
Physiology review, pathway
Neurology, Anatomy, Physiology
the brain stem, medulla
Cranial nerves

[@SH-on1gn]

Caloric test intent to induce horizontal nystagmus. Nystagmus is characterised by the slow movement of the eyes to one direction followed by fast saccade towards the opposite direction. The direction of nystagmus is usually determined by the direction of this fast saccade (and not by the direction from the initial slow movement). When cold water is inserted into the left ear, the eyes will move slowly to the left, but followed by a fast saccade movement to the right. The reason for COWS is hence because the direction to where the eyes quickly move to (in this case towards the right) to correct for the initial left movement determined the final direction of the nystagmus. Hence Cold - Opposite

[@inshafarooqi4136]

Can you tell me which will be the diseased vestibular system in this case?? Will it be the right vestibular system??

[@aminat7490]

Thank you! Helped me put all the pieces together

[@emanfazal5106]

So finalllyyy after watching thousands of videos on the same concept! This one helped. A BIG THANKSS!

[@arielmandelblum]

My neuro exam is in a few days, and your explanation FINALLY made this concept make sense. THANK YOU!

[@ri7265]

Thank you for explaining everything so clearly. And special thanks to explaining the acronym (which made no sense to me until you explained it)

[@Irmina08]

Thank you for this clear explanation, I've been reading and searching it everywhere and finally understood it here. So, thanks

[@star0178]

Finally, FINALLY understood this concept. Thanks so much

[@aravindnair6270]

Thank you sir for this really convincing explanation of such an intricate mechanism

[@ruynana]

You make it so easy to understand. Thank you so much!

[@pingpongwegjong]

Your explanation was really clear and helpful, thank you

[@chaithrijayasooriya717]

thank you so much!! you explained the concept so clearly :D

[@neelppatel007]

Thanks a lot this cleared my confusion. In harrison they have not elaborated it properly made me even more confused. COWS is for nystagmus CSWO for eye movement.

[@g.ioanaeliza7886]

Thanks for the video! Very well explained ! NISTAGMUS has 2 components : 1.slow phase and 2. fast phase ❄❄❄ ᙅ〇ᒪᗪ WATER ❄❄❄ when we inject with a syringe some COLD WATER in one ear ----the EYES will move SLOWLY to the SAME side as the syringe. (phase1) Then , the FAST phase will happen which will move the eyes in the OPPOSITE side of the syringe.(phase 2) So for COLD water, we get slow phase on tha same side , and fast phase on the opposite side, this is why the mnemonic says "CO" ,...cold-opposite actually refers to phase 2, to the fast phase of the nistagmus! (which is usually more easily observed when you look at the patient,because well it's sudden and it's fast and you say woaaa ! ) -------------------- ----------------- ------------------ ---------------------- 🔥🔥🔥🔥ᗯᗩᖇᗰ water when we inject warm water, phase 1 - aka the slow phase is moving the eyes OPPOSITE to the syringe with warm water. and phase 2 - the fast -phase is moving the eyes towards the syringe, to the SAME side as the syringe with warm water. So you notice the fast phase, beating to the same side as the syringe. WS- warm -same-refers to the phase 2 , the fast phase. _____________________________________- SO acronym COWS makes you remember in which direction is the PHASE 2 -THE FAST phase ! 🐮 COWS are fast, man ! I tell ya ! __________________________________ But we must always keep in mind that initially there is a slow phase(which is ..well slow, and smooth and not so spectacular and noticeable-, aka phase 1 that is actually remembered by the acronym CSWO.... The fast phase (phase 2) is under the control of the cerebral hemispheres and it requires the patient to be conscious.... .WHY IS THIS IMPORTANT ? I found this : The effect of the cold water in the ear is to fool the hair cells of the ampulla into thinking that the head is being turned to the opposite side. If this test is performed with cold water in an awake patient, the eyes will still tend to drift to the tested ear. The awake patient will try to compensate for this with fast sacchades back to midline, or some other point of fixation. This has given rise to the COWS mnemonic: Cold - Opposite, Warm - Same. COWS refers to the direction of fast nystagmus in the awake patient. In the comatose patient, there will be little or NO nystagmus, and the deviation of the eyes will be completely opposite (Warm- Opposite, Cold - Same). In fact, the presence of nystagmus on cold caloric testing in the apparently unconscious patient suggests that they are in fact conscious, and only pretending to be comatose. TAKEN from :derangedphysiology.com/main/required-reading/neurology-and-neurosurgery/Chapter%204.6.7/oculocephalic-and-cold-caloric-reflexes-cn-iii-iv-vi-and-viii I wrote this to make myself undestand hope it will help others too !𝔾𝕆𝕆𝔻 𝕃𝕌ℂ𝕂 with your studies folks !!!

[@sanketshirsolkar4247]

Thankyou man..grt help 🙌💯

[@kikicucci1910]

very clear explanation that made me finally understand the whole COWS thing!

[@ATA-wi2lh]

Thank you, can you do more? A lot of resources/professors just tell us what the test indicates but doesn't explain the circuit like this. This helps a lot.

[@step_zero]

sure thing

[@williamferreira3119]

Excellent explanation! thanks !

[@miancu3]

Great video

[@akshayshirur6096]

thankyou sir for making this concept crystal clear.

[@obscurer18]

This video is really helpful thank you so much. Can you make a video on what will happen if there is a lesion on the Vestibular nuclei or Vestibular nerve.

[@nugurimanideep]

Thank u that hepled me a lot.u made my day

[@mariaalthiadaffon9131]

this just made me understand the whole concept of the caloric test!!!! TY sir! ur a life saver

[@step_zero]

Happy to help!

[@komakid796]

thanks a ton. this really helped out.

[@rickybp2259]

Great work (y)

[@sophiaujeriksson]

wow this was so great thank you seriously

[@saraisa633]

Amazing explanation 👍🏼

[@josemanuelfuentesdelpozo9572]

thank you!! perfect explanation

[@Alphaparticles1000]

great job explaining it so simply. Thank you!

[@step_zero]

happy to help :)

[@nikkib837]

What a great video!! thank you

[@AbhishekChauhan-jq4qb]

Thanks...very....useful...👍🏻

[@mjclaudianava5397]

Thanks! Easily understood

[@10swastiksai37]

Best explanation 🙏🏻🙏🏻🙏🏻 Thanx

[@32_rahilchataiwalla74]

Great Explanation !

[@davonsworld1]

Thanks bro. You are a life saver!👊

[@step_zero]

no problem bro !

[@tawhidakhan6051]

Perfectly explained 🌺

[@ehe3653]

thank you, this helps so much~!

[@kknoppel1]

THANK YOU!

[@doctorh5413]

So what I understood from this video is: initially->CSWO, when the test is done->🐄. COWS. Thanks for correcting the misconception.

[@miancu3]

Doctor H there is no misconception. Cold opposite or warm same refers to the nystagmus, not the direction of gaze

[@wr44]

Agreed. There's not so much a misconception as a discordance with what people are talking about. COWS is referring to direction of nystagmus, which is opposite to the slow phase drift. Cold inhibits the canal, and causes a drift towards the tested ear and a fast phase saccade (nystagmus) away - or towards the opposite side (CO), whereas warmth causes a stimulation, subsequent slow phase away from the tested ear, but a corrective saccade (nystagmus) back to the same ear (WS). Hence COWS. The author was just referring to the slow phase rather than the saccade, so as long as you have the connection of COWS = nystagmus (or WOCS = slow) , then either way is a correct way to conceptualise it.

[@happylok5109]

Great 😎

[@kourasall7253]

Thanks a lot :)🙏🏾

[@rimy_3]

Thank you very much:)

[@martamovchan6752]

something difficult made so easy to understand!

[@supathidajiamsawad3828]

Thank you very much

[@namrataahuja5014]

Perfect.

[@leigh92]

Thank u!🙏

[@fatboy117]

thx so clear now

[@nafjach]

CSWO Is normally initial eye movement. Vestibular ocular reflex? And COWS is for nystagmus?

[@niharnayak6417]

Yes. CSWO for SACCADIC MOVEMENT ie the initial eye movements and COWS is for the nystagmus that follows it.

[@prathameshkhobragade8760]

Yes

[@opoppo6413]

beautiful!

[@harsimrankaur1815]

Thank u sir

[@bweerasooriya5020]

Thank u very much❤️❤️❤️

[@HamzaAli-om6fl]

Awesome

[@simkesims6345]

This video is awesome, great explanation. I have one question tho. Cold water sinks and warm water rises, I didnt really get how that affects the movement of endolymph. Can you elaborate please? Does that mean that cold water makes endolymph more dense and dense doesnt move as fast as warm endolymph? even if so, why does it make a change if we dont actually move, because endolymph doesnt move unless acceleration occurs right? How will warm endolymph start to move with no change in heads position. Im sorry if this is a stupid question, Im not good with physics xD

[@jedijooj]

thanks

[@sugaplumalex]

anyone had this test done and have vertigo for days after? mine isnt severe but ive got a rotating sensation, floor moving, fatigue..... its been 4 days im so scared its permanent

[@shvan98]

please tell me .. COWS is right for normal person ( without nystagmus) or for a patient who suffers with nystagmus ???

[@step_zero]

COWS refers to the nystagmus not the eye movement seen in the test.

[@margothaegemans1267]

Very nice explanation! Is it possible to receive the source or reference of the images used?

[@step_zero]

not sure where I put the file. Screenshot and reverse google image search is your best bet.

[@ahmedabdulwahab6421]

I love you man

[@ksk3139]

So the initial movement which is CSWO wasnt a Nystagmus, but the second corrective movement is a Nystagmus with COWS mnemonic, and it moves with fast saccadic movement ?

[@step_zero]

yup

[@andreasvoldstad4516]

So this is testing the Vestibular Ocular Reflex, and CSWO refers to this, while COWS refers to the nystagmus? How does this relate to the terms "left-beating" and "right-beating nystagmus"?

[@step_zero]

left and right beating just refers to the initial deviation the nystagmus is the corrective movement.

[@lilypotter3011]

Thanksssssss

[@step_zero]

your weeeeelcome

[@firstleader9115]

Hi after this test i have pain in my ear 7days untill now ?

[@step_zero]

see your doctor

[@bahiatid6841]

oh i finally get this

[@hemantjain9157]

How water reaches inner ear , i mean there is a tympanic membrane in between? Can someone explain plz

[@step_zero]

the water does not reach the inner ear it just heats or cools the fluid already there

[@BoredT-Rex]

skip to 5:10 for explanation

[@mb-3faze]

Seems you're going to get the same results as with a well performed head impulse test.

[@doctorn4240]

Thanks brother

[@shvan98]

Nimesh Parmar can you tell me the COWS is right for normal person of for a patient with nystagmus ?

[@doctorn4240]

Shvan Jalal cows basically stands for the nystagmus, the fast component, which means when I use cold water to normal person the eyes will deviate to the side of irrigation , now right after deviation it will go back to midline (NYSTAGMUS) , that’s why they say cold linked with opposite , the opposite is nystagmus , not the initial eye movement keep in mind . So cows for normal person for the NYSTAGMUS

[@shvan98]

Dear,I understood it ,thank u for repetition, but My question was that (If the COWS is using for testing the normal person to see what happen in nystagmus patient ) or ( COWS is using for nystagmus patient ) ,, I think it must use for normal person 🌹

[@doctorn4240]

Shvan Jalal we don’t use cows generally to a normal person but , a person is comatose then this maneuver is performed to see cranial nerve 3-6 , if patient cranial nerves are damaged then it would be CSWO for the nystagmus.

[@doctorn4240]

That indicates brainstem lesion as there is a impairment of cranial nerve 3-6 , used for extraoccular muscles. If person is comatose , and this maneuver is showing CSWO for the NYSTAGMUS then you suspect lesion in brainstem :)

[@mohammedbilal1147]

The direction of nystagmus is defined by the fast component. Thus COWS hold true.

[@step_zero]

that's what I said in the video

[@asmaajo1913]

🌹

[@lgalina997]

So this test would not be appropriate or necessary for a conscious patient, correct?

[@step_zero]

yes

[@Deadsoulcutie]

Wait what.. why?

[@usmle6947]

You don't need subscribe only , you have to be paid , thanks a punch

[@user-ne6uk8zm2s]

한국말로 해석좀해주실분..

[@step_zero]

내가 그것을 시도하고 번역 할 때 youtube는 돈을 요구한다 :(

[@MultiKarzi]

Cows is too confusing Thanks for explanations

[@step_zero]

yup there are plenty of silly terms in medicine that make no sense

[@miancu3]

Cold opposite, warm same refers to the direction of nystagmus.

[@tarendranikhra3447]

Treatment also apprise

[@justinchop5531]

Can you explain why a physician does this rather than a nurse? Is it simply because a nurse cannot diagnose brain death? Or can you cause harm by doing this on someone? I’m guessing it is the former and not the latter.

[@step_zero]

Nurses can diagnose brain death. Usually, it's under the supervision of a physician. The diagnosis of brain death can be done by others than just a doctor but the law varies on where you are. This is more of a legal thing.

[@pimppaul27]

hey guy. thank you....freaking COWS.

[@step_zero]

np friend

[@fawz9955]

Thank you very much