Treatment of Apogeotropic Horizontal Canal Benign Paroxysmal Positional Vertigo

Inclusion Criteria: * a history of brief episodes of positional vertigo, * direction-changing horizontal nystagmus beating toward the uppermost (apogeotropic nystagmus) or undermost (geotropic nystagmus) ear in both the lateral head turning positions, * no spontaneous nystagmus during upright sitting position, and * absence of identifiable central nervous system disorders that could explain the positional vertigo and nystagmus. Exclusion Criteria: * central positional nystagmus with identifiable CNS lesions that could explain the positional nystagmus