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Background: In this study, we aimed to examine functional VOR values with and without optokinetic background stimulation in fHIT (functional head impulse test) in individuals with motion sickness. Methods: Forty-two individuals between the ages of 18–50 years were included in study. The lateral fHIT test was applied to the motion sickness group and the control group with and without dynamic optokinetic (OKN) background stimulation. Results: In the control group, no significant difference was observed in the correct response percentages (% CA) for fHIT and OKN-fHIT for the right and left lateral canals (p > 0.05). In the MS group, a significant difference was observed when comparing fHIT and OKN-fHIT correct response percentages for the right and left lateral canals (p < 0.05). Conclusions: It has been observed that the optokinetic background triggers the disease in individuals with MS, and there is a decrease in the percentage of correct readings in the fHIT. [ABSTRACT FROM AUTHOR]

The vestibulo-ocular reflex (VOR) is the main vision-stabilising system during rapid head movements in humans. A visual-vestibular mismatch stimulus can be used to train or adapt the VOR response because it induces a retinal image slip error signal that drives VOR motor learning. The training context has been shown to affect VOR adaptation. We sought to determine whether active (self-generated) versus passive (externally imposed) head rotation vestibular training would differentially affect adaptation and short-term retention of the active and passive VOR responses. Ten subjects were tested, each over six separate 1.5-h sessions. We compared active versus passive head impulse (transient, rapid head rotations with peak velocity ~ 150 °/s) VOR adaptation training lasting 15 min with the VOR gain challenged to increment, starting at unity, by 0.1 every 90 s towards one side only (this adapting side was randomised to be either left or right). The VOR response was tested/measured in darkness at 10-min intervals, 20-min intervals, and two single 60-min interval sessions for 1 h post-training. The training was active or passive for the 10- and 20-min interval sessions, but only active for the two single 60-min interval sessions. The mean VOR response increase due to training was ~ 10 % towards the adapting side versus ~2 % towards the non-adapting side. There was no difference in VOR adaptation and retention between active and passive VOR training. The only factor to affect retention was exposure to a de-adaptation stimulus. These data suggest that active VOR adaptation training can be used to optimally adapt the passive VOR and that adaptation is completely retained over 1 h as long as there is no visual feedback signal driving de-adaptation. [ABSTRACT FROM AUTHOR]

Background: Falls frequency increases with age and particularly in neurogeriatric cohorts. The interplay between eye movements and locomotion may contribute substantially to the occurrence of falls, but is hardly investigated. This paper provides an overview of current approaches to simultaneously measure eye and body movements, particularly for analyzing the association of vestibulo-ocular reflex (VOR) suppression, postural deficits and falls in neurogeriatric risk cohorts. Moreover, VOR suppression is measured during head-fixed target presentation and during gaze shifting while postural control is challenged. Using these approaches, we aim at identifying quantitative parameters of eye-head-coordination during postural balance and gait, as indicators of fall risk.Methods/design: Patients with Progressive Supranuclear Palsy (PSP) or Parkinson's disease (PD), age- and sex-matched healthy older adults, and a cohort of young healthy adults will be recruited. Baseline assessment will include a detailed clinical assessment, covering medical history, neurological examination, disease specific clinical rating scales, falls-related self-efficacy, activities of daily living, neuro-psychological screening, assessment of mobility function and a questionnaire for retrospective falls. Moreover, participants will simultaneously perform eye and head movements (fixating a head-fixed target vs. shifting gaze to light emitting diodes in order to quantify vestibulo-ocular reflex suppression ability) under different conditions (sitting, standing, or walking). An eye/head tracker synchronized with a 3-D motion analysis system will be used to quantify parameters related to eye-head-coordination, postural balance, and gait. Established outcome parameters related to VOR suppression ability (e.g., gain, saccadic reaction time, frequency of saccades) and motor related fall risk (e.g., step-time variability, postural sway) will be calculated. Falls will be assessed prospectively over 12 months via protocols and monthly telephone interviews.Discussion: This study protocol describes an experimental setup allowing the analysis of simultaneously assessed eye, head and body movements. Results will improve our understanding of the influence of the interplay between eye, head and body movements on falls in geriatric high-risk cohorts. [ABSTRACT FROM AUTHOR]

Background: Baseline visual acuity (VA) loss from static to dynamic head conditions assessed using the Dynamic Visual Acuity Testing (DVAT) have not been established in NCAA football players. DVAT assesses the Vestibulo-Ocular Reflex (VOR) which is measured in Logarithm of the Minimum Angle of Resolution (logMAR). Decreased VA beyond baseline measures may detect VOR impairment and impact treatment protocols and assist in return to play decisions post-concussion. Hypothesis/Purpose: To establish normative VA mean scores during a static head posture as well as dynamically during the DVAT with a head speed of 150 deg/s in the pitch (vertical) and yaw (horizontal) planes rotating 20 degrees in each direction. Study Design: Descriptive study, Diagnostic Tests. Methods: Sixty-seven, NCAA Division I College football players (age= 19.68 ± 1.53) completed static VA and DVAT assessment in the pitch and yaw planes during baseline concussion testing at the beginning of the 2014 regular football season. Comparison of VA was evaluated by calculating the difference in players' static and dynamic VA values using the DVAT. Results: Static VA for all participants (n=67) was -0.232 ± 0.109 logMAR. Dynamic VA for participants (n=67) was 0.0845 ± 0.159 in pitch and -0.007 ± 0.141 in yaw at 150 deg/sec. Mean losses in VA during pitch and yaw at 150 deg/ sec were 0.317 ± 0.140 and 0.227 ± 0.133, respectively. Conclusions: VA diminishes during head movement at 150 degrees/sec. Loss of acuity beyond established normative values from baseline may be indicative of VOR dysfunction, especially secondary to head trauma. The assessment of visual acuity function with head movements of 150 deg/sec can potentially identify concussion and subsequent sequelae. Further research is recommended. [ABSTRACT FROM AUTHOR]

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