unidirectional nystagmus

[Deepa100]

😡
I don't understand what this means. Nystagmus has a slow and fast component, which I understand. Unidirectional nystagmus is defined as "fast component always beats in the same direction". I don't understand that. Is this saying as you ask the pt to move his eyes to follow and object to Left or Right, his fast component will always point to the direction of deficit (vestibular, for example?)
Thanks for any help!

 

[lildave2586]

What you've stated is essentially Alexander's law, the nystagmus will increase when gazing toward the direction of the fast phase. Here is a good video that shows some examples of rotary nystagmus, which is seen in BPPV. This is a non-unidirectional nystagmus. The video also shows some good examples of unidriectional horizontal nystagmus.

http://www.youtube.com/user/peterjohns84#p/a/u/0/cZlXvRlxrRE

 

[Deepa100]

Excellent! Thanks!