Subjective Visual Vertical Tilt Attraction to the Side of Rod Presentation: Effects of Age, Sex, and Vestibular Disorders.

Objective: The aim of this study was to evaluate the effect of initial rod position on the subjective visual vertical (SVV) tilt and to investigate the effect of sex and age on the SVV tilt induced by this initial position.
Study Design: Prospective cross-sectional study.
Setting: Tertiary referral center.
Patients: The study included 6598 consecutive patients with a large range of vestibular disorders and 333 control subjects. The mean age was 55 years (range, 3-97), and the sex ratio was 0.6.
Intervention: SVV was measured by presenting a phosphorescent rod 12 times in total darkness with a 45-degree deviation from the vertical alternatively on the right and left. The patient was asked to replace the bar vertically with a remote control.
Results: On average, SVV at each iteration was tilted to the side of the rod presentation. It was stronger in female subjects, in younger individuals (<20 years) and seniors (>50). It was also higher in patients with a left vestibular loss in comparison to those with a right involvement.
Conclusions: These effects suggest that short-term visual memory and multisensory cortical processing interfere with SVV measurements.