“BPPV is estimated to affect roughly 50% of all people at some time in their lives and becomes progressively more common with age. During periods when attacks are not occurring, the diagnosis is made from the characteristic history and by the exclusion of other disorders that can cause similar dizzy symptoms. When attacks are occurring, the Hallpike positional test is diagnostic. In the commonest form of BPPV the Hallpike test is positive (i.e. induces vertigo and nystagmus) when the affected ear is down most. Up to 10% of cases may involve both ears.”

Menieres Society (https://www.menieres.org.uk/information-and-support/symptoms-and-conditions/bppv)