Influence of Otoliths on the Vestibulo-Ocular Reflex in Horizontal Canal Benign Paroxysmal Positional Vertigo

Abstract

Objectives: The aim of the study was to evaluate the possible alteration of the vestibulo-ocular reflex (VOR) in patients with horizontal canal benign paroxysmal positional vertigo (h-BPPV) using the video head impulse test (vHIT).Methods: This was a prospective case-control study of BPPV patients. We include-ed 133 patients with h-BPPV who underwent the vHIT prior to the positioning test. The control group consisted of 76 normal subjects who also underwent the vHIT. The vHIT parameters of gain and asymmetry were assessed, and clinical parameters such as treatment duration, number of canalith reposition maneuvers executed and recurrence rates were evaluated. The VOR and clinical parameters were compared between the h-BPPV and control group. The VOR parameters of h-BPPV canalolithiasis were also compared with those of cupulolithiasis.Results: The mean age of the patients was 56.5 years and the male to female ratio was 1:2.02. Of the patients, 75 were diagnosed as having the canalolithiasis type of h-BPPV, while the other 58 had the cupulolithiasis type. The mean vHIT gains of the ipsi-lesional horizontal canal plane were 1.13 and 1.15 in the h-BPPV and control group, respectively (p=0.564). However, the asymmetry of the VOR was significantly higher in the h-BPPV than the control group (p=0.013), while the gains and asymmetries of the vHIT in the canalolith and cupulolith types were not significantly different (p=0.454, p=0.826).Conclusions: The asymmetry of VOR is significantly elevated in the cupulolith type of hBPPV.