Here we present a patient with a classic clinical picture of BPPV. She experienced the same type of positional vertigo a year ago, which spontaneously passed after a couple of weeks.
Dix-Hallpike test to the left: a strong sense of vertigo, and after a long latency, a barely noticeable Ny which suits the left posterior canal (cw). I immediately perform Epley maneuver for the left ear, but in the second position, appears strong Ny, characteristic for canalolithiasis of the right posterior. Maneuver completed and control Dix-Hallpike test was completely bilateraly negative.
The next day the patient returns with worsening of symptoms and even stronger positional vertigo. DH to the right causes a very intense downbeat Ny, while on the left it has also a torsional component in ccw direction. Everything suggests canalolithiasis of the right anterior canal (Ny down and with torsional component to the rightside). However, it sounds unlikely for someone who had a canalolithiasis of the left posterior a day before to return the next day with canalolithiasis counterpart on the opposite side. So since we know that the canalolithiasis of the left posterior is in question, we ask ourselves how is it possible to manifest with downebeathing nystagmus?! However, I am not the first one to encounter this phenomenon:
Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo Presenting with Torsional Downbeating Nystagmus: An Apogeotropic Variant
Anterior canal BPPV and apogeotropic posterior canal BPPV: two rare forms of vertical canalolithiasis
The authors of these two works explain this phenomenon by stating that the otoliths got stuck in the ampular arm of the canal.
I treated this patient with an Epley maneuver for the left ear, and repeated it several times. The patient was much better, but strange feeling in the head didn’t resolved; somthing like “dizziness”, but without any positional vertigo. The patient performed exercises by Brandt-Daroff every day and she complained on discomfort when repeating the exercise on the right side. After two weeks, the patient comes in with a worsening of symptoms; a strong vertigo while going to bed the nightbefore, but sincethan constant dizziness disapeared. Now the DH test revealed characteristic nystagmus for the posterior left semicircular canal. Only one Epley maneuver was enough to completely resolve symptoms of vertigo and dizziness and since than she is cimpletely fine.
After this, how do we know whether the patient has the canalolithiasis of the anterior canal, or an apogeotropic form of the canalolithiasis of the posterior canal? In the aforementioned papers one difference was suggested: canalolithiasis of the anterior canal is downbeat component of the nystagmus is dominant where torsional component is absent or weak, since at the ageotropic form of posterior canal BPPV the torsional component of the nystagmus is more pronounced. In our case this remark wasn’t obvious. Anyhow, it’s important when you see positional downbeat nystagmus to distinguish benign lesion such BPPV from much more serious central lesion, since we know that such lesions could present with positional downbeating nystagmus!
After discard the possibility of central vestibular lesion, you can switch to repositioning maneuvers. I recommend to try with “deep head hanging” repositioning maneuver suggested for both anterior canals; if not successfull than proceed with Epley. The aim is to reposition dislodged otoconia back to utriculus and to resolve patient from vertigo.