Journal of Vestibular Research-Equilibrium & Orientation最新文献

Background: Patients with vestibular loss have reduced wayfinding ability, but the association between vestibular loss and impaired steering spatial navigation is unclear.

Objective: To evaluate whether vestibular loss is associated with reduced steering navigation performance in a virtual reality (VR) environment containing obstacles.

Methods: 17 ambulatory adults with vestibular loss were age/sex-matched to healthy controls. Participants traversed a VR hallway with obstacles, and their navigation performance was compared using metrics such as collisions, time, total distance travelled, and speed in single and multivariate analysis.

Results: In univariate analysis there was no significant difference in collisions between vestibular patients and controls (1.84 vs. 2.24, p = 0.974). However, vestibular patients took more time, longer routes, and had lower speeds to complete the task (56.9 vs. 43.9 seconds, p < 0.001; 23.1 vs. 22.0 meters, p = 0.0312; 0.417 vs. 0.544 m/s, p < 0.001). These results were confirmed in multivariate analysis.

Conclusions: This study found that patients with vestibular loss displayed slower gait speeds and traveled longer distances, though did not make more collisions, during a VR steering navigation task. Beyond the known influence of vestibular function on gait speed, vestibular loss may also contribute to less efficient steering navigation through an obstacle-laden environment, through neural mechanisms that remain to be elucidated.

Background: Hypoxia influences standing balance and vestibular function.

Objective: The purpose here was to investigate the effect of hypoxia on the vestibular control of balance.

Methods: Twenty participants (10 males; 10 females) were tested over two days (normobaric hypoxia and normoxia). Participants stood on a force plate (head rotated leftward) and experienced random, continuous electrical vestibular stimulation (EVS) during trials of eyes open (EO) and closed (EC) at baseline (BL), after 5 (H1), 30 (H2) and 55-min (H3) of hypoxia, and 10-min into normoxic recovery (NR). Vestibular-evoked balance responses were quantified using cumulant density, coherence, and gain functions between EVS and anteroposterior forces.

Results: Oxyhemoglobin saturation, end-tidal oxygen and carbon dioxide decreased for H1-3 compared to BL; however, end-tidal carbon dioxide remained reduced at NR with EC (p≤0.003). EVS-AP force peak-to-peak amplitude was lower at H3 and NR than at BL (p≤0.01). At multiple frequencies, EVS-AP force coherence and gain estimates were lower at H3 and NR than BL for females; however, this was only observed for coherence for males.

Conclusions: Overall, vestibular-evoked balance responses are blunted following normobaric hypoxia >30 min, which persists into NR and may contribute to the reported increases in postural sway.

Background: Naturalistic head accelerations can be used to elicit vestibular evoked potentials (VestEPs). These potentials allow for analysis of cortical vestibular processing and its multi-sensory integration with a high temporal resolution.

Methods: We report the results of two experiments in which we compared the differential VestEPs elicited by randomized translations, rotations, and tilts in healthy subjects on a motion platform.

Results: An event-related potential (ERP) analysis revealed that established VestEPs were verifiable in all three acceleration domains (translations, rotations, tilts). A further analysis of the VestEPs showed a significant correlation between rotation axes (yaw, pitch, roll) and the amplitude of the evoked potentials. We found increased amplitudes for rotations in the roll compared to the pitch and yaw plane. A distributed source localization analysis showed that the activity in the cingulate sulcus visual (CSv) area best explained direction-dependent amplitude modulations of the VestEPs, but that the same cortical network (posterior insular cortex, CSv) is involved in processing vestibular information, regardless of the motion direction.

Conclusion: The results provide evidence for an anisotropic, direction-dependent processing of vestibular input by cortical structures. The data also suggest that area CSv plays an integral role in ego-motion perception and interpretation of spatial features such as acceleration direction and intensity.

The Barany society published recently the consensus document for the diagnostic criteria of persistent postural perceptual dizziness (PPPD). In this commentary we highlight the benefits of this new diagnosis and possible problems that can arise during the use of the criteria in day to day clinical practice at a University Clinic for Psychosomatic Medicine. The diagnostic criteria of PPPD are compared to those of somatic symptom disorder and bodily distress disorder. We think that a discussion from a psychosomatic point of view is important to improve the understanding between different specialties and how PPPD fits into the broader framework of psychosomatic medicine.