Objective: One of the problems in the management of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) is the difficulty in determining the affected ear using Ewald's second law. The purpose of this study is to develop the new "bow and lean test (BLT)" to easily determine the affected ear of HSC-BPPV and evaluate its efficiency.
Methods: We compared the efficiency between the classic method and BLT in 26 patients with HSC-BPPV. The classic method is based on Ewald's second law comparing the intensity of nystagmus or symptoms in the head roll test. BLT is based on the direction of both "bowing nystagmus" and "leaning nystagmus" at the head's bowing and leaning state in a sitting position. The affected ear is the same direction of bowing nystagmus in canalolithiasis and the same direction of leaning nystagmus in cupulolithiasis.
Results: In 26 patents (15 canalolithiasis, 11 cupulolithiasis), 3 (11.5%) patients did not show a prominent affected ear in the classic method, and 7 (26.9%) patients showed the different affected ear between the two methods. All 10 patients were successfully treated with just one trial of barbecue rotation based on the affected ear in BLT. Three patients did not show any bowing or leaning nystagmus. The side with canal paresis in all four patients, who showed significant canal paresis in bithermal caloric tests, was equal to the affected ear based on BLT.
Conclusions: The "bow and lean test" (also called "Choung's test") is a new method that can easily determine the affected ear of HC-BPPV.