Characterization of Vestibular Perception in Patients with Persistent Postural-Perceptual Dizziness

Objective: To assess vestibular (i.e., passive self-motion) perception in patients diagnosed with persistent postural-perceptual dizziness (PPPD).Study Design: Case-controlled, cross-sectional, observational investigation.Setting: Single-center laboratory-based study.Patients: Thirteen patients with PPPD, 13 age-matched healthy control volunteers. Of those with PPPD, eight had co-occurring vestibular migraine (VM).Interventions: All participants completed a vestibular threshold test battery reflecting perception with predominant inputs from (a) the otoliths (1-Hz interaural y-axis translation, 1-Hz superior-inferior z-axis translation), (b) the semicircular canals (2-Hz yaw rotation, 2-Hz tilts in the planes of the vertical canal pairs), and (c) and canal-otolith integration (0.5-Hz roll tilt).Main Outcome Measures: Direction-recognition thresholds for each vestibular threshold test condition.Results: Across all patients with PPPD, higher thresholds for superior-inferior z-translations thresholds in comparison to age-matched healthy control participants were identified (p < 0.001). Those patients with co-occurring VM and PPPD (PPPD/+VM) displayed significantly higher z-translation thresholds (p = 0.006), whereas patients with PPPD without VM (PPPD/-VM) displayed significantly higher roll tilt thresholds (p = 0.029).Conclusions: Patients with PPPD did not display a global worsening of passive self-motion perception as quantified by vestibular perceptual thresholds. Instead, patients with PPPD displayed elevated thresholds for only roll tilt and z-translation thresholds, with the relative change in each threshold impacted by the co-occurrence of VM. Because both z-translation and roll tilt motions are reliant on accurate gravity perception, our data suggest that patients with PPPD may exhibit impaired processing of graviceptive cues.