Interpreting Roll Test for Horizontal Canal BPPV

[Kaitlyn Sevilla]

In the vestibular lecture, it says the following:

Roll test tests for horizontal canal BPPV
Direction of horizontal nystagmus:

– Geotropic (toward the earth): canalithiasis affecting most symptomatic side

– Ageotropic (away from the earth):
– >1 minute duration: cupulolithiasis affecting least symptomatic side
– <1 minute duration: canalithiasis affecting least symptomatic

I’ve never learned that ageotropic nystagmus can indiate canalithiasis if it lasts <1 minute… I’ve always learned ageotropic nystagmus indicates cupulolithiasis.

Can you provide the resource for this?

Thanks!

[Chrissy Durrough Lugge]

Hi Kaitlyn! Sometimes the displaced otoconia sneak onto the other side of the cupula (the “anterior arm” of the semicircular canal). In that case, they are not stuck to the cupula but cause ageotropic/apogeotropic nystagmus. This type of canalithiasis is relatively rare, though it does constitute around 50% of people with ageotropic nystagmus. It’s probably more in the vestibular weeds than you need for the NCS exam – knowing big picture for BPPV is more critical!

https://pmc.ncbi.nlm.nih.gov/articles/PMC6766685/

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