Brain activation in persistent postural-perceptual dizziness (PPPD) in response to various visual motion stimuli...

Patients with persistent postural-perceptual dizziness (PPPD) perceive unsteadiness associated with abnormal ego- or visual motion perception. We tested for altered functional brain activation of PPPD patients and healthy subjects (HC) while applying various visual motion stimuli (VS).

Functional brain activation of 32 PPPD patients and 35 age- and gender-matched HC was examined using 3 types of VS-videos: a rollercoaster front row ride (rollercoaster, ROL), optic flow (flowfield, FF), and a silent black-and-white movie (movie, MOV). Fixation of a centered target was used as REST condition. After each trial, the level of visually induced egomotion perception was recorded.

Patients rated VS-induced egomotion larger than HC (ROL > FF > MOV). Brain activation differed between the 3 types of VS for all participants: ROL elicited activation in the Rolandic operculum (OP) and insula, FF in the cerebellum, and MOV in the cingulate cortex and frontal operculum. Whole brain activation for all VS was larger in the patients' visual cortex. Region of interest (ROI) analysis revealed opposite group-related activation patterns in vestibular processing areas: patient's activation was larger during ROL and FF but lower during MOV. Activation in OP2, insula, and uvula became larger with increasing PPPD-handicap and postural sway (FF). VS-evoked brain activation was not correlated with egomotion perception.

The larger activation in the patients' visual cortex during VS supports the notion of abnormal visual dependence, a core feature of PPPD. However, it does not seem to be related to abnormal egomotion perception. Activation patterns of vestibular processing areas suggest that patients differentiate between VS types stronger than HC. VS-related activation in these areas became larger with PPPD-related disability, supporting an abnormal readiness to respond to visual egomotion-inducing stimuli.