This study indicates that head position during sleep is likely to contribute to the pathogenesis of benign paroxysmal positional vertigo (BPPV). Seventy-two patients, consisting of 54 with posterior semicircular canal BPPV and 18 with lateral semicircular canal BPPV, were examined (BPPV group). Seventy-six healthy individuals of statistically the same age and sex as those of the BPPV group were also examined (healthy group).
This study revealed that the percentage of people who always sleep in the same head position, particularly with the right side or left side down, amounted to 61 % of the BPPV group and 24% of the healthy group, which was significantly different (p<0.005). In 39 BPPV patients, (mean follow-up of 7.7 years) the recurrence rate was 41%, and the persistence rate was 13%. When patients were consulted to avoid having a fixed head position during sleep, the recurrence rate decreased to 18%, and the persistence rate decreased to 3%. In addition, almost all recurrent patients were ones who could not avoid a fixed head position during sleep. There was no correlation between the affected side of BPPV and the particular head position during sleep. In patients with latent inner ear disorders and/or utricular damage of unknown origin, habitually sleeping with the head position down on the right side or left side might induce otoconial detachment, causing BPPV and recurrence or persistence of BPPV. As an important possible cause of BPPV, the head position during sleep should be taken into consideration.