Abstract
IntroductionFunctional dizziness comprises a class of dizziness disorders, including phobic postural vertigo (PPV), that cause vestibular symptoms in the absence of a structural organic origin. For this reason, functional brain mechanisms have been implicated in these disorders.MethodsHere, functional network organization was investigated in 17 PPV patients and 18 healthy controls (HCs) during functional magnetic resonance imaging with a visual motion stimulus, data initially collected and described by Popp et al. (2018). Graph theoretical measures (degree centrality [DC], clustering coefficient [CC], and eccentricity) of 160 nodes within six functional networks were compared between HC and PPV patients during visual motion and static visual patterns.ResultsGraph theoretical measures analyzed during the static condition revealed significantly different DC in the default‐mode, sensorimotor, and cerebellar networks. Furthermore, significantly different group differences in network organization changes between static visual and visual motion stimulation were observed. In PPV, DC and CC showed a significantly stronger increase in the sensorimotor network during visual stimulation, whereas cerebellar network showed a significantly stronger decrease in DC.ConclusionThese results suggest that the altered visual motion processing seen in PPV patients may arise from a modified state of sensory and cerebellar network connectivity.
Highlights
Functional dizziness comprises a class of dizziness disorders, including phobic postural vertigo (PPV), that cause vestibular symptoms in the absence of a structural organic origin
We found that brain networks of PPV patients are connected differently in the two conditions studied, compared to healthy controls (HC)
We found that the sensorimotor network initially displayed decreased degree centrality (DC) and clustering coefficient (CC) during static visual stimulation, but that these measures increased to a greater extent in PPV patients during visual motion
Summary
Functional dizziness comprises a class of dizziness disorders, including phobic postural vertigo (PPV), that cause vestibular symptoms in the absence of a structural organic origin. For this reason, functional brain mechanisms have been implicated in these disorders. Functional dizziness includes phobic postural vertigo (PPV) (Brandt, 1996), chronic subjective dizziness (Ruckenstein & Staab, 2009), visually induced dizziness (Bisdorff, Von Brevern, Lempert, & Newman-Toker, 2009; Bronstein, 1995), and space and motion discomfort (Jacob, Lilienfeld, Furman, Durrant, & Turner, 1989). Because PPPD is a recent classification and less well established in the literature, we use the term functional dizziness to discuss previous literature using patient populations described having chronic subjective dizziness, visually induced dizziness, or space and motion discomfort
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