Teasing Out The Torsional Nystagmus with BPPV

Do you ever find it difficult to see the torsional component of nystagmus with the Dix-Hallpike test? At times we have, and it can be concerning given the possibility of the  vertical nystagmus being indicative of a central vestibular disorder. There is, however, a clinical trick to help tease out any torsional component. 

It's All About Semicircular Canal Orientation

As the video in this blog reviews, the nystagmus with BPPV is in the same plane as the semicircular canal that is affected. So, with being able to understand the orientation of the canals we can bias the nystagmus to reveal the torsional component and if need be the vertical component.

To see more of the torsional component with BPPV affecting either the posterior or anterior canal, all the patient needs to do is simply look in the direction perpendicular to the plane of the affected canal.  

The below chart outlines the effect of lateral gaze with Dix-Hallpike testing. 

So, with BPPV affecting the right posterior canal the torsional nystagmus will be more noticeable with Dix-Hallpike testing to the right and right gaze. 

With BPPV affecting the right anterior canal the torsional nystagmus will be more noticeable with Dix-Hallpike testing (can actually be to either side) and left gaze. 

What Happens If There Is No Torsional Nystagmus?

If lateral gaze in either direction does not elicit torsional nystagmus, then a central vestibular disorder should be considered.

Signs & symptoms of a central vestibular disorder include, but are not limited to:

• Pure down or up beat nystagmus (i.e. with the vertical nystagmus there is no torsional component).
• Nystagmus that is just as prevalent in room light then when the individual cannot see anything (visual fixation is removed with infrared or Frenzel goggles).
• Direction changing nystagmus when looking for gaze evoked nystagmus. 
• Nystagmus that does not fatigue with repeat positional testing (Dix-hallpike and/or Roll testing). With BPPV the nystagmus with positional testing will fatigue or become less prevalent with repeat testing. 
• Non-conjunct eye motion (i.e. the eyes do not move together as a pair) or other positive cranial nerve findings.
• Spontaneous and gaze evoked nystagmus (these are positive with peripheral vestibular disorders as well).
• Positive saccadic eye motion testing  and other coordination testing. 
• Positive long tract signs.
• Ataxia.
• Slurred speech.
• Drop attacks.
• Double vision.
• Problems swallowing/choking.
• Severe, unrelenting headaches. 

We hope that this gives you a simple tool to help you tease out any torsional component of the nystagmus. That being said, any test should not be used alone, but rather compliment the history and other findings. 

If you have any questions regarding the above, please feel free to contact us at North 49. 

(E) [email protected]

(T) 306.343.7776