Pathophysiological Variants of Horizontal Semicircular Canal Benign Paroxysmal Positional Vertigo: Toward an...

Objective: To critically synthesize the available evidence on the pathophysiological variants of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) and to propose an integrative model based on otoconial location and cupular dynamics to explain their clinical presentation and therapeutic implications. Methods: A scoping review was conducted through a search of PubMed/MEDLINE, Scopus, and the Cochrane Library for studies published between January 1996 and May 2026. Studies describing pathophysiological variants, biomechanical mechanisms, nystagmus patterns, or therapeutic maneuvers in HSC-BPPV were included. A total of 26 studies met the inclusion criteria and underwent qualitative analysis. Results: Six principal mechanical configurations of horizontal canal positional vertigo were identified: long-arm canalolithiasis, short-arm canalolithiasis, canal-side cupulolithiasis, utricular-side cupulolithiasis, canalith jam, and light cupula. The available evidence suggests that these variants represent different mechanical states determined by otoconial location, otoconia-cupula interaction, canal obstruction, or alterations in cupula-endolymph density. This model explains the direction, intensity, and duration of positional nystagmus, the findings observed during the supine roll test and the bow and lean test, as well as the variability in response to repositioning maneuvers. A practical classification integrating pathophysiology, clinical findings, and treatment is proposed. Conclusions: HSC-BPPV may be more appropriately understood as a spectrum of mechanical states in which the configuration of otoconial debris and its interaction with the cupula influence the nystagmus pattern, clinical presentation, and therapeutic response. This integrative model may improve diagnostic accuracy and guide treatment selection, although prospective validation is required.