The Head-Bending Test in Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo

Objectives: This study aimed to investigate clinical significance of a head-bending test in benign paroxysmal positional vertigo (BPPV) involving the posterior semicircular canal (PC-BPPV).Methods: We retrospectively recruited 256 patients with unilateral PC-BPPV between January 2016 and December 2021, and assessed the clinical characteristics of patients showing head-bending nystagmus (HBN).Results: Of 256 patients, 138 (53.9%) showed HBN. Most patients (n=136, 98.6%) had downbeat nystagmus with (n=38) or without (n=98) torsional component. The remaining two patients had pure upbeat and torsional nystagmus, respectively. The torsional component was directed to the contralesional side in all. Between patients with and without HBN, there were no significant differences in clinical characteristics such as age, lateralization, types of BPPV (canalolithiasis or cupulolithiasis), and success rate of repositioning maneuver.Conclusions: Head-bending test may be useful in predicting the diagnosis and lateralization of PC-BPPV.