Variants of benign paroxysmal positional vertigo in relation to head position during sleep

Patients with posterior- and lateral-(canal)-benign paroxysmal positional vertigo (BPPV)-canalolithiasis sleep in the affected-ear-down head position. Posterior-BPPV-canalolithiasis typically affects the right than left ear; sleeping in the right-ear-down head position may be causal.

To investigate the relationship between habitual head position during sleep and the onset of BPPV variants.

Among 1,170 cases of BPPV variants with unknown etiology, the affected ears, habitual head positions during sleep based on interviews, and relationships among them were investigated.

Posterior-BPPV-canalolithiasis and lateral-BPPV-canalolithiasis-geotropic affected the right ear significantly more often. Significantly more patients with posterior-BPPV-canalolithiasis and lateral-BPPV-canalolithiasis-apogeotropic habitually slept in the right-ear-down head position. Patients with posterior- and lateral-BPPV-canalolithiasis and light cupula were more likely to sleep habitually in the affected-ear-down position than in the healthy-ear-down head position; no relationship was observed in patients with posterior- and lateral-BPPV-cupulolithiasis. In patients with posterior-BPPV-canalolithiasis and lateral-BPPV-canalolithiasis-geotropic, the proportion of right-affected ears in those sleeping habitually in the right-ear-down head position was significantly greater than that for the left-affected ear.

A habitual affected-ear-down head position during sleep may contribute to BPPV-canalolithiasis and light cupula onset, but not BPPV-cupulolithiasis onset. However, habitual sleeping in the right-ear-down head position cannot explain the predominance of right-affected ears.