Brain Dynamics of Persistent Postural-Perceptual Dizziness at Rest Reveal Alterations in Multisensory and Motor Areas

Background

Persistent Postural-Perceptual Dizziness (PPPD) is a chronic functional disorder with unsteadiness and postural instability, attributed to altered multisensory integration and visual dependence. fMRI studies report altered connectivity in several regions, however, dynamic connectivity remains unexplored.

Objectives

We characterized resting-state brain dynamics in 17 patients with PPPD and 20 matched healthy controls (HC), and their relationship to clinical and postural measures.

Methods

Co-Activation Patterns (CAPs) were derived from resting-state fMRI scans for four seeds relevant to multisensory integration, motor output and vestibular processing – right temporo-parietal junction (rTPJ), caudate nucleus, hippocampus and operculo-parietal area 2 (OP2) – and their temporal metrics compared between groups. Partial Least Squares Correlation (PLSC) related CAPs to mood, vertigo, stress, and visual dependence for gait and postural control.

Results

Patients with PPPD showed altered dynamics seeded from rTPJ (decrease of a salience-coupled CAP, increased entries into a visual/dorsal-attention-coupled CAP), caudate nucleus (increased time in a default mode-coupled CAP, decrease of a salience/visual-coupled CAP) and hippocampus (increase of a default-mode-coupled CAP), but not OP2. PLSC yielded two significant latent components: the first linked rTPJ, OP2 and hippocampal CAPs sharing visual network co-deactivation to stress, mood, vertigo and visual dependence for gait; the second linked all caudate and two rTPJ CAPs to postural sway with eyes closed (visual dependence). Individual brain-behavior scores correlated in both groups.

Conclusion

Resting-state dynamics are altered in multisensory and motor regions in PPPD, but preserved in OP2, the core vestibular cortex. Brain-behavior organization appears shared across groups, with shifted dynamics in patients.

Curved arrows indicate dynamic functional connectivity patterns (Co-Activation Patterns) differing between patients with PPPD and HC (the direction is indicated by the small straight arrows). Dashed arrows indicate latent components of brain-behavior coupling identified through PLSC analysis. (rTPJ: right temporo-parietal junction; OP2: parietal operculum area 2; AP: antero-posterior).