Benign paroxysmal positional vertigo and migraine-associated dizziness are common. The prevalence of benign paroxysmal positional vertigo seems to be higher in patients with migraine-associated dizziness than in those without migraine.

A database of 508 patients seen at the primary author's balance clinic was analysed to determine the prevalence of migraine, as defined by International Headache Society criteria, in patients with benign paroxysmal positional vertigo.

The percentage of patients with dizziness or vertigo who met criteria for migraine was 33.7 per cent, with a prevalence of benign paroxysmal positional vertigo of 42.3 per cent. When excluding patients with migrainous vertigo, patients with migraine frequently had benign paroxysmal positional vertigo (66.7 per cent vs 55.8 per cent), although this finding was not statistically significant.

The results for the entire sample suggest that, after excluding patients with migrainous vertigo, patients with migraine seem more likely to have benign paroxysmal positional vertigo; however, this association was not significant, probably because of the small sample size.

Using American bullfrog models under normal conditions and under vestibular dysfunction, we investigated whether mechanical vibration applied to the ear could induce otoconial dislodgement.

Vibration was applied to the labyrinth of the bullfrog using a surgical drill. The time required for the otoconia to dislodge from the utricular macula was measured. Vestibular dysfunction models were created and the dislodgement time was compared with the normal models. The morphology of the utricular macula was also investigated.

In the normal models, the average time for otoconial dislodgement to occur was 7 min and 36 s; in the vestibular dysfunction models, it was 2 min and 11 s. Pathological investigation revealed that the sensory hairs of the utricle were reduced in number and that the sensory cells became atrophic in the vestibular dysfunction models.

The otoconia of the utricle were dislodged into the semicircular canal after applying vibration. The time to dislodgement was significantly shorter in the vestibular dysfunction models than in the normal models; the utricular macula sustained significant morphological damage.

To investigate what kinds of stimuli are effective in detaching otoconia from the cupula in three experimental models of cupulolithiasis.

Three experimental models of cupulolithiasis were prepared using bullfrog labyrinths. Three kinds of stimuli were applied to the experimental models. In experiment one (gravity), the labyrinth preparation was placed so that the cupula-to-crista axis was in the horizontal plane with the canal side in the downward position. In experiment two (sinusoidal oscillation), the labyrinth preparation was placed 3 cm from the rotational centre of a turntable, which was sinusoidally rotated with a rotational cycle of 1 Hz and a rotational angle of 30°. In experiment three (vibration), mechanical vibration was applied to the surface of the bony capsule around the labyrinth using a surgical drill.

In experiments one, two and three, the otoconial mass was respectively detached in 2 out of 10 labyrinth preparations, none of the labyrinth preparations, and all of the labyrinth preparations.

Vibration was the most effective stimulus for detaching the otoconia from the cupula in these experimental models of cupulolithiasis.