Subjective visual vertical in posterior canal benign paroxysmal positional vertigo patients before and after Canalith repositioning maneuvers

Background: The subjective visual vertical (SVV) is a measure of otolith-mediated verticality perception. The aim of this study was to test otolith function using the SVV in patients with posterior canal (PC) benign paroxysmal positional vertigo (BPPV) before and after Epley’s Canalith repositioning maneuver (CRM). Methodology: This study included 20 PC BPPV patients and 20 healthy control subjects. SVV was tested using special equipment, at the time of BPPV diagnosis, then after CRM, and then 1 week after the resolution of vertigo and nystagmus. SVV was determined from clockwise (CW) and counter-clockwise (CCW) directions. The absolute average and the conventional numerical average was calculated. Results: Using the conventional method, there was no statistically significant difference between BPPV and their controls regarding either the CW or the CCW-SVV or the average slope. There was no statistically significant difference between CW and CCW-SVV in the patients. There was no statistically significant difference in the mean SVV values or the distribution of normal and abnormal results or the distribution of the SVV tilt between both-sided BPPV. Using the absolute average, SVV tilt was significantly higher in the patients than the controls. The preset angle affected the result. The mean SVV was significantly lower after resolution of BPPV than before treatment. Conclusion: Absolute SVV average was more accurate than numerical SVV average. There was a reduction of the SVV tilt after the CRM in BPPV patients. So, the SVV test can be used as a prognostic test for BPPV improvement after treatment.