Short-arm型後半規管BPPVが疑われた4症例の検討

抄録

Benign paroxysmal positional vertigo (BPPV) is one of the most common causes of vertigo, and the posterior canal is the most frequently involved structure because of its anatomical position. In the majority of posterior canal BPPV cases, a particle-repositioning maneuver, such as the Epley maneuver, is effective, since the otoconia is thought to be located in the long arm of the posterior canal. However, Oas et al. has proposed a subtype of posterior canal BPPV, known as short-arm type BPPV, in which the otoconia is assumed to be located not in the long arm of the posterior canal, but in the short arm (between the utricle and the cupula). Here, we present four cases of BPPV that presumably involve the short-arm type posterior canal. The duration of nystagmus was extended in all four cases when the head was moved as in the Dix Halllpike test. Furthermore, when the head was moved back to a sitting position, the reversal of nystagmus was not or very faintly observed. As a treatment, the Epley maneuver was initially attempted, but this treatment was not effective. However, vibration methods (involving the application of vibration to the mastoid process of the affected ear with the intact ear positioned downwards) were effective in all four cases.