Background:
Benign paroxysmal positional vertigo (BPPV) is a common cause of
episodic vertigo in which otoconia (calcium carbonate crystals) become
detached from their normal location on the macula of the otolith
organs.[1] They can then find their way into the semicircular canals
(SCC), become free-floating or attached to the cupula, and create
abnormal sensations of motion when the position of the head is changed
with respect to the pull of gravity. BPPV of the horizontal canal
(hcBPPV) is less commonly diagnosed than BPPV of the posterior canal
BPPV (pcBPPV), in part because most emergency department and primary
care physicians do not attempt to distinguish the canal variants.[2,
3] The supine roll test (SRT) is primarily used to diagnose hcBPPV,
while the Dix-Hallpike test is primarily used to diagnose pcBPPV.[4,
5]
BPPV is usually treated with particle repositioning maneuvers that move
the otoconia out of the SCC: the Epley or Semont maneuvers for pcBPPV
and, for example, the Gufoni, Zuma, or Lempert (barbeque roll) maneuvers
for hcBPPV.[4-7] We report here a woman with hcBPPV who came to the
emergency department with acute positional vertigo and positional
nystagmus and experienced a favorable outcome despite the wrong side and
the wrong canal being diagnosed and consequently receiving the wrong
treatment maneuver. To explain this seeming paradox, we simulated the
movement of otoconia within the labyrinth in a right-sided hcBPPV in
response to an Epley treatment maneuver for left-sided pcBPPV. Our
simulations suggest that an extended Epley maneuver (i.e., the patient’s
head being turned beyond the conventional 45o angle to
60o in the second step) caused the otoconia to leave
the horizontal SCC, resulting in this patient’s successful outcome.