# Spatial Orientation Impairment in Patients With Bilateral Vestibulopathy and Persistent Postural–Perceptual Dizziness

## TL;DR

Patients with BVP and PPPD show impaired spatial orientation, even when their vestibular function is normal, suggesting central processing issues.

## Contribution

This study demonstrates that PPPD, despite normal vestibular function, is associated with spatial orientation impairments, possibly due to central suppression of vestibular input.

## Key findings

- PPPD patients showed significantly lower spatial orientation accuracy compared to healthy controls.
- Both BVP and PPPD patients reported higher spatial orientation discomfort despite similar self-assessed spatial abilities.
- The impairment in PPPD suggests central suppression of vestibular input, not just peripheral dysfunction.

## Abstract

Two chronic forms of dizziness—bilateral vestibulopathy (BVP) with a loss of vestibular input, and functional dizziness with normal vestibular function—present with the key symptom of postural and gait imbalance. In BVP, this is associated with spatial disorientation. Here, we investigated whether persistent postural–perceptual dizziness (PPPD) in patients with normal vestibular function also affects spatial orientation, because there is evidence that central multisensory misintegration plays a crucial role in PPPD.

Thirty‐two patients with BVP (mean age 52.44 ± 12.00 years; 17 females), 43 patients with PPPD (mean age 45.93 ± 11.72 years; 25 females), and 32 healthy controls (HC, mean age 44.78 ± 14.40 years; 15 females) participated in a clinical bedside test investigating spatial orientation abilities (three‐dimensional real‐world pointing task, 3D‐RWPT). This test includes a cognitive (mental rotation) and a vestibular paradigm (body rotation around yaw axis with eyes closed). Participants reported their perceived spatial abilities and levels of spatial anxiety /orientation‐related discomfort through standardized questionnaires.

Patients with BVP and PPPD showed significantly lower accuracy (i.e., larger angular deviations) in the 3D‐RWPT compared to HC (BVP: 9.62° ± 3.21°, PPPD: 9.16° ± 3.85°, HC: 7.77° ± 2.86°; p = 0.03), especially in the subtasks that rely on vestibular function (BVP: 8.11° ± 5.51°, PPPD: 6.62° ± 4.46°, HC: 4.45° ± 2.33°; p < 0.01). All cohorts had comparable levels of self‐assessed spatial abilities, while both BVP and PPPD patients showed higher levels of spatial orientation discomfort.

This impairment of spatial orientation in PPPD patients with normal vestibular function could be a sign of (potentially anxiety‐driven) central suppression of vestibular input, which is required for the continuous updating of the internal representation of body motion and position relative to the environment.

When asked to point at remembered targets before and after passive whole‐body rotations, patients with bilateral vestibular loss (BVP) and persistent postural–perceptual dizziness (PPPD) showed substantially decreased accuracy compared to healthy controls. In BVP patients, this is due to the complete vestibular loss; in PPPD patients, it could be a sign of disease‐dependent central suppression of vestibular input during head movements and locomotion.