Objective: To demonstrate that a single therapy is effective for treating all subtypes of horizontal canal benign paroxysmal positional vertigo (HC-BPPV).
Study design: Prospective study.
Methods: Patients with HC-BPPV (n = 89) were diagnosed when the supine to the head-lateral test resulted in geotropic or ageotropic bilateral horizontal nystagmus. Three subtypes of HC-BPPV were defined by their characteristic patterns of nystagmus as well as by their speculative mechanism. Canalolithiasis (Can) denotes geotropic nystagmus induced by free-moving otoliths in the HC. Two forms of cupulolithiasis, characterized by otoliths attached either on the utricle-sided (Cup-U) or the canal-sided (Cup-C) cupula, were identified by whether ageotropic nystagmus resolved or changed to geotropic nystagmus on follow-up tests. Forced prolonged position (FPP), lying on the healthy side for 12 hours to easily move free otoliths to the utricle, has proven successful in treating Can. Although Cup-U and contralateral Cup-C were associated with the same positional nystagmus pattern, FPP with lying on the side of the weaker nystagmus was found to be effective treatment, as well as consistent with the speculated underlying mechanism.
Results: All HC-BPPV patients including 49 with Can, 11 with Cup-C and 29 with Cup-U had complete resolution of symptoms and positional nystagmus after less than four treatment sessions.
Conclusions: FPP with lying on the side of the weaker nystagmus, combined with careful observation of nystagmus evolvement, was found to be effective treatment for all subtypes of HC-BPPV in this series.