Volume ratio and distribution rate in patients with orthostatic vertigo/dizziness using MR imaging: a comparison with vertiginous diseases.

Background: Orthostatic dizziness/vertigo (ODV) is characterized by lightheadedness owing to postural changes.
Aims/objectives: To measure the endolymphatic space (ELS)/total fluid space (TFS) volume ratio and the distribution rate of endolymphatic fluid (ELF) of patients with ODV and compare them with those of control subjects (CS).
Materials and Methods: This study included 22 patients (44 ears) with ODV and 52 controls (104 ears, CS). The ELS/TFS volume ratio (%) and distribution rate (%) of the inner ear components were measured using 3-dimensional magnetic resonance imaging.
Results: In the ODV group, the mean ELS/TFS volume ratios of the cochlea, vestibule, and semi-circular canals (SCCs) were 12.1%, 18.6%, and 18.1%, respectively; the mean ELS distribution rates for the cochlea, vestibule, and SCCs were 27.3%, 26.2%, and 46.6%, respectively. The ELS distribution rate of the vestibule was significantly lower ( p  < .01) and the ELS distribution rate of the SCCs was significantly higher in the ODV than in the CS group ( p  < .01).
Conclusions and Significance: The ELS distribution rate in the vestibule + SCCs among patients with ODV did not differ from that in the CS; ELF in the vestibule moved to the SCCs, and a large amount of ELF was distributed only in the SCCs.