vestibular lesion

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MudPhud20XX

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Okay so I still don't get this and would really appreciate if someone can enlighten me.

Kaplan nuero says:

"A lesion of the vestibular nuclei or nerve on the left produces a vestibular nystagmus with a slow deviation of the eyes toward the lesion and a fast correction back to the right."

So the way I understood VOR is that if you rotate your head to right, nystagmus (fast component) will be directed to the right and the slow component will be deviated toward the left. Did I get this correctly?

So with the lesion on the left, you are artificially creating a situation as if your head is rotated to the right?

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Yes.
"Jerk" Nystagmus is due to a vestibular lesion and has a slow phase and a rapid phase. Herk nystagmus can be due to an asymmetric vestibular lesion (if you have symmetric lesion on both sides, you would not get jerk nystagmus). This is compared to "pendular" nystagmus in which the oscillations in both directions are equal speed. Pendular nystagmus is due to a visuomotor feedback problem (baby who has poor visual acuity hence underdeveloped fixation reflexes) and thus is similar to a tremor, and is not due to vesitbular lesions.

You can think of it as your head moving or the world moving. I don't know if this hurts or helps but this is how I think of it.
I am sitting on a stationary train with my head turned staring out the window looking at one of the many trees (so my right ear is towards the front of the train, my left ear towards the back). If I have a lesion on the left (losing all of its tonic input), its as if the train starts moving to to my right (i.e. forward). My eyes (slowly) follow the tree to the left as it passes by and then rapidly snap back to the right to fixate on the next tree that comes, slowly follows that tree till its gone, snaps back onto the next one, etc.
 
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