Background: Persistent postural-perceptual dizziness (PPPD) is a common functionalvestibular disorder characterized by persistent symptoms of non-vertiginous dizzinessand unsteadiness that are exacerbated by upright posture, self-motion, and exposureto complex or moving visual stimuli. Recent physiologic and neuroimaging data suggestthat greater reliance on visual cues for postural control (as opposed to vestibular cues—aphenomenon termed visual dependence) and dysfunction in central visuo-vestibular networksmay be important pathophysiologic mechanisms underlying PPPD. Dysfunctionsare thought to involve insular regions that encode recognition of the visual effects ofmotion in the gravitational field.Methods: We tested for altered activity in vestibular and visual cortices during selfmotionsimulation obtained via a visual virtual-reality rollercoaster stimulation using functionalmagnetic resonance imaging in 15 patients with PPPD and 15 healthy controls(HCs). We compared between groups differences in brain responses to simulated displacementsin vertical vs horizontal directions and correlated the difference in directionalresponses with dizziness handicap in patients with PPPD.results: HCs showed increased activity in the anterior bank of the central insular sulcusduring vertical relative to horizontal motion, which was not seen in patients with PPPD.However, for the same comparison, dizziness handicap correlated positively with activityin the visual cortex (V1, V2, and V3) in patients with PPPD.conclusion: We provide novel insight into the pathophysiologic mechanisms underlyingPPPD, including functional alterations in brain processes that affect balance controland reweighting of space-motion inputs to favor visual cues. For patients with PPPD,difficulties using visual data to discern the effects of gravity on self-motion may adverselyaffect balance control, particularly for individuals who simultaneously rely too heavily onvisual stimuli. In addition, increased activity in the visual cortex, which correlated withseverity of dizziness handicap, may be a neural correlate of visual dependence.
Altered Insular and Occipital Responses to Simulated Vertical Self-Motion in Patients with Persistent Postural-Perceptual Dizziness
Chiarella G;
2017-01-01
Abstract
Background: Persistent postural-perceptual dizziness (PPPD) is a common functionalvestibular disorder characterized by persistent symptoms of non-vertiginous dizzinessand unsteadiness that are exacerbated by upright posture, self-motion, and exposureto complex or moving visual stimuli. Recent physiologic and neuroimaging data suggestthat greater reliance on visual cues for postural control (as opposed to vestibular cues—aphenomenon termed visual dependence) and dysfunction in central visuo-vestibular networksmay be important pathophysiologic mechanisms underlying PPPD. Dysfunctionsare thought to involve insular regions that encode recognition of the visual effects ofmotion in the gravitational field.Methods: We tested for altered activity in vestibular and visual cortices during selfmotionsimulation obtained via a visual virtual-reality rollercoaster stimulation using functionalmagnetic resonance imaging in 15 patients with PPPD and 15 healthy controls(HCs). We compared between groups differences in brain responses to simulated displacementsin vertical vs horizontal directions and correlated the difference in directionalresponses with dizziness handicap in patients with PPPD.results: HCs showed increased activity in the anterior bank of the central insular sulcusduring vertical relative to horizontal motion, which was not seen in patients with PPPD.However, for the same comparison, dizziness handicap correlated positively with activityin the visual cortex (V1, V2, and V3) in patients with PPPD.conclusion: We provide novel insight into the pathophysiologic mechanisms underlyingPPPD, including functional alterations in brain processes that affect balance controland reweighting of space-motion inputs to favor visual cues. For patients with PPPD,difficulties using visual data to discern the effects of gravity on self-motion may adverselyaffect balance control, particularly for individuals who simultaneously rely too heavily onvisual stimuli. In addition, increased activity in the visual cortex, which correlated withseverity of dizziness handicap, may be a neural correlate of visual dependence.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.