Altered Resting-State Neural Oscillations and Functional Connectivity in Persistent Postural-Perceptual Dizziness

Background: Persistent postural-perceptual dizziness (PPPD) is a chronic functional neuro-otologic disorder marked by persistent dizziness, unsteadiness, and visual dependence. Its electrophysiological mechanisms remain unclear. This study examined resting-state EEG spectral power and functional connectivity in PPPD and their associations with postural stability and clinical symptoms. Methods: Forty patients with PPPD and 40 age- and sex-matched healthy controls were studied with an eyes-closed resting-state EEG recording. Static postural stability was measured with the Pro-Kin system. Spectral power was calculated for delta, theta, alpha, beta, and gamma bands. Functional connectivity was assessed using the weighted phase lag index. Results: Static posturography showed impaired postural stability in patients with PPPD compared with healthy controls. Spectral power analysis showed increased theta-band relative power over the frontal and left parieto-occipital regions. Connectivity analysis showed increased prefrontal-temporal and decreased temporal-occipital connectivity in the theta band, increased fronto-parieto-occipital and decreased parietal-temporal connectivity in the alpha band, and decreased cerebellar and temporal, central connectivity in the gamma band. Conclusions: PPPD was associated with frequency-specific alterations in resting-state cortical oscillations and functional connectivity involving cognitive-affective, visual, and sensorimotor networks. Resting-state EEG may help characterize network-level abnormalities in PPPD.