Last week we reviewed a post discussing the occasional finding of downbeat vertical nystagmus when bringing the patient back up to the seated position after performing canalith repositioning (AKA the Epley maneuver) for posterior canal BPPV. Well, last week, I saw a particularly unusual presentation of that particular unusual presentation. I had a referral from a local Otolaryngologist that was comfortable that this particular patient had BPPV, but he wasn’t sure which canal was involved and decided to send him to us for a second opinion. The diagnosis was complicated by the fact that the patient had amblyopia (lazy eye) in his left eye.
On exam, his initial Dix-Hallpike to the right elicited classic right posterior canal nystagmus, both in direction and duration. On rolling the patient’s head away from the affected side (position #2 of the Epley maneuver), he had a short burst of rotary nystagmus in the same direction. This is considered a good sign as it means the otoconia are continuing to travel in the same direction, and have not receded back in to the posterior canal. In position #3 (nose down) we got no response. Then, on rising to the sitting position (Position #4) we got a burst of downbeat vertical nystagmus. At this point, I felt confident that the particles had exited the posterior canal.
There is controversy over what downbeat nystagmus on rising to position #4 means. Because there is a distinct change in nystagmus pattern, most practitioners agree that the particles are no longer stimulating the posterior canal. There is disagreement as to whether those particles are now in the vestibule stimulating the utricle, or whether they have migrated into the anterior canal. In my experience, patients report feeling like they are being thrown forward or backward (not spinning), and virtually all of these patients are better the next day. Because of these two facts, my belief has been that down beat nystagmus on rising from position #4 represents the particles entering the vestibule, where they are dissolved.
Back to the patient: after resting for about five minutes and explaining what I perceived to be going on, we did a second right Dix-Hallpike. It was negative as expected. I typically take patients through at least a second round of repositioning. When rolling the head to the left (position #2) we saw a sharp burst of upbeat vertical nystagmus, in position #3 (nose down) we got no response, and in rising to position #4, we got the same short burst of downbeat nystagmus.
At this point, I had to make a decision. Were the particles in the vestibule stimulating the utricle, or had they migrated in to the right anterior canal? My decision was to stop for the day, and if the particles were in the vestibule, they would dissolve and the patient would be a lot better in 48 hours. Also, by this time, if the particles were in the anterior canal, they were likely scattered and not primed for repositioning.
We asked the patient to return after the weekend for a progress check. Come back next week to see how this played out.
Photo courtesy of John Epley