Department of Otolaryngology Head & Neck Surgery, Faculty of Medicine, Niigata Univ. Niigata, Niigata, Japan
Objective: To examine the fixation stability in patients with Persistent Postural-Perceptual Dizziness (PPPD) when presented with moving visual stimuli that may exacerbate their vestibular symptoms.
Study Design: Cross-sectional study.
Setting: Tertiary referral center.
Patients: 25 patients with PPPD and 7 with unilateral vestibular hypofunction (UVH) showing chronic vestibular symptoms (> 3 months).
Main Outcome Measures: Three different moving visual stimuli ((1) checkerboard stimulus reversed in contrast at 12 Hz, (2) optokinetic stimulus by black-and-white vertical stripes, (3) radial optic flow stimulus with white dots expanding, and stationary white screen as the control) were presented on a PC screen for 30 seconds each. The subjects were instructed to fixate on the center of the screen, and their fixation stability was measured using a computed eye tracking system. Mann-Whitney U tests were conducted on the number of fixations, mean duration of fixation, saccades count, and bivariate contour ellipse area (BCEA) between the two groups. The BCEA represents the area of the ellipse where the fixation point is detected with a certain probability, thus lower BCEA-values indicate higher/better fixation stability.
Results: The BCEAs during checkerboard and optokinetic stimulation were significantly higher in the PPPD group than those in the UVH group. There were no significant differences in fixation stability during optic flow stimulation and stationary white screen between the two groups.
Conclusions: Patients with PPPD cannot fixate on the center of the screen during checkerboard and optokinetic stimulation, which would result in an exacerbation of vestibular symptoms by moving visual stimuli in PPPD. Professional Practice Gap & Educational Need: The core vestibular symptoms of PPPD are exacerbated by upright posture/walking, active or passive movement, and exposure to moving or complex visual stimuli, with exacerbation by visual stimulation being the most characteristic. However, the mechanism of exacerbation by visual stimuli is not known. In the first place, there are no reports that have examined the fixation stability in patients with PPPD.
Learning Objective: To learn about the fixation stability unique to PPPD when compared to UVH, which is considered difficult to differentiate from PPPD.
Desired Result: 1. To gain a better understanding of the pathogenesis of PPPD. 2. To improve the ability to differentiate and accurately diagnose PPPD from other chronic vestibular disorders.
Level of Evidence - Level Ⅳ - Historical cohort or case-control studies
Indicate IRB or IACUC: This study was approved by the IRB of Niigata University
Medical and Dental Hospital on September 14, 2020. (#2020-0242)