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

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.