The Liberatory Manoeuvres for Posterior Canal Benign Paroxysmal Positioning Vertigo

Abstract

Canalolithiasis with a freely floating heavy clot of otoconia in the posterior semicircular canal can explain the direction, latency, duration, and fatiguability of the nystagmus of typical p-BPPV. Canalolithiasis also explains the efficacy of positioning “liberatory manoeuvres” when the head is quickly positioned from the challenging head position to the opposite side in the spatial plane of the affected posterior canal. If the clot is washed out of the canal a “liberatory nystagmus” that beats toward the affected now uppermost ear indicates success because of ampullofugal stimulation of the cupula. If the clot gravitates back toward the cupula a positioning nystagmus that beats downward toward the unaffected ear indicates failure because of ampullopetal stimulation of the cupula. Complete recovery after a single manoeuvre is achieved in about 50 to 60%, and after repetitive manoeuvres in more than 90%, of the cases. The recurrence rate is approximately 50% of cases within years, mostly (20%) within the first two weeks. Recurrences are due to re-entry of the debris into the canal and should be treated with the same manoeuvre.

• benign paroxysmal positioning vertigo
• posterior semicircular canal
• canalolithiasis
• cupulolithiasis
• liberatory manoeuvre