4.外側半規管型BPPV

抄録

The horizontal semicircular canal (HSCC) type of benign paroxysmal positional vertigo (BPPV) (H-BPPV) is caused by either canalolithiasis or cupulolithiasis and affects the horizontal semicircular canal. When the patient with HSCC canalolithiasis performs a lateral head turn toward the affected ear, free-floating debris will create an ampullopetal endolymph flow. As a result, a geotropic nystagmus (fast phase toward the ground) will be present (GH-BPPV). When the patient turns away from the affected side, free-floating debris will create an ampullofugal flow. When the patient with HSCC cupulolithiasis performs a lateral head turn toward the affected ear, the cupula undergoes an ampullofugal deflection causing apogeotropic nystagmus. A head turn to the opposite side creates an ampullopetal deflection. The natural history of H-BPPV is good and several positioning techniques to treat H-BPPV have been developed, but a few patients with refractory H-BPPV exist. In this review, I explain how to diagnose H-BPPV, how to diagnose the affected side in H-BPPV, and how to treat H-BPPV with canalith repositioning maneuvers. I show two types of GH-BPPV. One type shows transient positioning geotropic nystagmus, and the other type shows continuous positional geotropic nystagmus. Finally, I explain how to deal with refractory H-BPPV and the surgical treatment of H-BPPV.