Cases of recurrent benign paroxysmal positional vertigo (BPPV) were evaluated retrospectively to examine the affected semicircular canal, the pathophysiology (canalithiasis or cupulolithiasis), and the affected side. The subjects were 152 patients with recurrent BPPV out of 571 consecutive BPPV patients treated at one clinic over a period of 10 years and 5 months. The subjects had up to 5 BPPV recurrences and there were 260 recurrences in total. Of these, 97 (37%) affected the same ear and the same canal and were caused by the same pathophysiology; 93 (36%) occurred on the same side, but affected a different canal and/or were caused by a different pathophysiology; 11 (4%) occurred on the same side, but affected a different canal and were suspected to have been caused by a different pathophysiology; 43 (17%) affected the contralateral side; and 16 (6%) were suspected to have affected the contralateral side. The affected side was defined as the side on which a deposit of otoliths detached from the utriculus. The affected canal and the pathophysiology were also defined based on a lesion with otolith deposits. Our results showed that about 75% of recurrent BPPV cases occur on a fixed side on which otoliths are likely to be detached, while 25% may have a general risk factor such as osteoporosis that can cause detachment of otoliths from the utriculus on both sides. About one-third of recurrent BPPV cases affected the same ear and canal, and were caused by the same pathophysiology; and another one-third occurred in the same ear and affected different canals and/or had a different pathophysiology. These findings suggest that a preference for head position during sleep may be related to the lesion site in which otoliths are deposited.
