The clinical significance of direction-fixed mono-positional apogeotropic horizontal nystagmus

Epley's Influence on Horizontal Canal BPPV Variants

Dr. Epley has been instrumental in defining the mechanisms and treatment of BPPV variants, including those of the horizontal canals. Cupulolithiasis is a horizontal canal BPPV variant usually defined as direction-changing apogeotropic nystagmus. In recent years, the favored cupulolithiasis mechanism of otoconia adhering persistently to the cupula has been called into question. Epley was the first to propose mechanistic theories which better match the most recent evidence. From the beginning, he has demonstrated mastery over the semicircular canal pathology and otoconial mechanics.

Less talked variants of benign paroxysmal positional vertigo

The diagnostic criteria were established for benign paroxysmal positional vertigo (BPPV), the most common vestibular disorder worldwide, by the Barany Society in 2015. This marked an important milestone in the diagnosis and treatment of BPPV. However, there still remain uncertainties and ambiguities regarding the clinical features and pathophysiology of BPPV, and its clinical variants. In this manuscript, we will discuss 1) the emerging and controversial syndromes of BPPV (i.e., canalolithiasis of the anterior canal, cupulolthiasis of the posterior canal, and lithiasis of multiple canals) with updates, 2) atypical nystagmus according to the canal involved (e.g., nystagmus induced by head position changes in the pitch plane in horizontal canal BPPV, and positional downbeat nystagmus in posterior canal BPPV), 3) persistent geotropic positional nystagmus. Consideration of these uncommon types and manifestations of BPPV would broaden our understanding of BPPV pathomechanisms and allow differentiation from central vertigo and nystagmus.