Abstract

Objectives
We aimed to assess the clinical significance of spontaneous nystagmus (SN) in horizontal semicircular canal benign paroxysmal positional vertigo (HC-BPPV).
Methods
Twenty-four patients who were diagnosed with HC-BPPV in our hospital from January 2015 to December 2016 were recruited. Various bed-side examinations including SN in both sitting and supine position, head roll test and bithermal caloric test was evaluated. The number of canalith repositioning maneuvers were counted in all patients.
Results
18.2% of geotropic HC-BPPV and 38.5% of apogeotropic HC-BPPV showed SN. There was no significant difference between presence of SN and the direction of initial nystagmus (p=0.386, two-tailed Fisher's exact test). The mean number of otolith repositioning maneuvers in patients with SN was 3.29±1.799 and this was significantly higher than in patients without SN (1.76±0.831) (p=0.009). Although the mean number of repositioning maneuver in patients in apogeotropic HC-BPPV and SN (3.80±1.924) tended to be higher than those who were diagnosed with apogeotropic HC-BPPV without SN (1.88±1.991) (p=0.035), the post-hoc analysis with Bonferroni correction revealed that it was not significant because it was higher than the adjusted p value (p=0.017). the initial direction of nystagmus was changed into the opposite direction in 29.17% of patient. However, this change was not different according to presence of SN (p=0.374, two-tailed faisher's exact test).
Conclusions
The presence of SN in HC-BPPV may be associated with lower treatment response. In particular, cautions are needed in patients with apogeotropic HC-BPPV.

• Keywords: Benign paroxysmal positional vertigo; Horizontal canal; Spontaneous nystagmus;