Twenty-nine individuals (41.43%) presented an affected unilateral posterior canal. Fifteen patients (21.43%) presented a pure horizontal direction-changing positional nystagmus consistent with a diagnosis of horizontal canal BPPV. Twelve individuals (17.14%) presented a unilateral down-beating nystagmus, suggesting possible anterior canal BPPV. In addition, 14 patients (20%) showed multiple positional nystagmus during the examination corresponding to simultaneous multi-canal BPPV, 5 had bilateral posterior canal BPPV and 2 presented a positional down-beating nystagmus in both left and right Dix-Hallpike manoeuvres and the head-hanging manoeuvre, which is highly suggestive of anterior canal BPPV. However, seven individuals showed positional horizontal and vertical side-changing nystagmus that could not be explained by single-canal BPPV. These patients with multiple positional nystagmus showed changing patterns of positional nystagmus at follow-up.

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Canal paresis is not associated with a lower outcome to repositioning.

Maximum SPV of vertical HSN was higher in BPPV patients with posterior canal BPPV (n = 10) than in controls (p = 0.04). Moreover, the time constant of vertical HSN was significantly lower for posterior canal BPPV when compared with controls (p < 0.02).

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