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Background. Although treatments for dizziness as a result of visual-vestibular mismatch (VVM) exist, the lack of prognostic information about this population affects the quality of their rehabilitation care. Despite numerous studies showing that individuals presenting with non-specific dizziness are likely to have VVM, and despite VVM being recognized by to the international classification of vestibular disorders by the Bárány Society, it remains unknown how prevalent this condition is. The VVM diagnostic questionnaire has not yet been generally accepted as a useful tool for diagnosis. There are inadequate criteria for prescribed vestibular rehabilitation for individuals with VVM, and little evidence to support the selection of treatment programs among this population. Treatment outcomes are not particularly successful because of a lack of guidelines. Studies have been performed that address dizziness severity, but no reliable biometric measurement has been developed yet. A potential measure of VVM could be responses of the autonomic nervous system (ANS) during vestibulo-visual challenges given the anatomical relationship between the vestibular system and the ANS. Individuals with both peripheral and central vestibular dysfunction exhibit symptoms and signs of autonomic dysfunction as a result of vestibulo-autonomic interactions. Moreover, changes in postural sway are a tangible indicator of the balance during any disturbance to the vestibular system. In this dissertation the use of measures of electrodermal activity (EDA) of the ANS and postural acceleration are explored in vestibular migraine (VM) individuals both with and without VVM. Purpose. The aims of this dissertation were to examine, in VM adults: 1) the presence of VVM and visual dependency in individuals presenting with complaints of dizziness using the VVM questionnaire and the Rod and Frame protocol, respectively; 2) the potential of EDA activity and postural responses to differentiate between VM and healthy individuals when accommodating for postural instability and visual-vestibular conflict; and 3) the effect of exposure to different visual contexts of VR environments on EDA phasic and tonic responses and postural responses in identified VM adults with VVM. Participants. Seventy-four participants with dizziness were enrolled in Aim 1 (70% female, mean age 45.4 ± 14.8 years), and a total of 45 participants (23 healthy, 45.5% female, mean age 34± 9 years) and (22 VM adults, 61% female, mean age 34.4 ± 8, including 12 VM adults with VVM, 77% female, mean age 34±9) were enrolled in the experimental studies for Aims 2 and 3. Methods. In Aim 1, the VVM questionnaire and the Rod and Frame protocol were used to test the presence of VVM and visual dependency, respectively. In Aims 2 and 3, a Shimmer 3 IMU sensor accelerometer was used to assess trunk acceleration in the anterior-posterior, medial-lateral, and vertical directions with different VR environments (STREET and SPACE). EDA measurements were assessed with a wireless wearable Shimmer 3 GSR+. Clinical measures of dizziness and mobility were concurrently tested. A linear mixed model was used to examine the effect of VM with and without VVM on standing balance and EDA activity. Results. The presence of VVM, headache, and visual dependency demonstrated a strong association. EDA activity and postural acceleration significantly differed between VM and healthy individuals. Specific subjective reporting tools, including ABC, VSS-SF, VVAS, and DHI, were reliable for distinguishing between VM and healthy individuals. Lastly, VM individuals with VVM exhibited significantly greater NPL of trunk accelerations in the vertical plane than VM individuals without VVM with the STREET environment compared to the SPACE environment. Conclusion. VVM and visual dependency could be risk factors for developing vestibular migraine and should be included in the examination protocol of those populations. Combining measures of EDA and trunk acceleration may provide objective measures of the severity of dizziness related to VVM. Results of this dissertation suggest that the use of EDA measures combined with NPL-Vert could provide potential neurophysiological biomarkers in identifying VVM in adults with vestibular migraines. Further, the correlation between the characteristics of the visual environment and the subjective dizziness outcome measure may contribute to establishing a threshold-tolerance basis for designing a vestibular rehabilitation program that will more precisely target symptom severity. / Physical Therapy

Virtual reality (VR) is becoming increasingly important in balance training. However, the influence of VR generated visual perturbation, through the novel virtual moving room paradigm, is unknown. Thirty healthy individuals had their static balance assessed on a BTrackS balance plate under eight different conditions: baseline eyes open and eyes closed with and without VR, unexpected toward and away moving VR perturbation, and expected toward and away moving VR perturbation. Multiple statistical analyses were conducted, and the results revealed significantly higher postural sway variables in the unexpected moving toward trials compared to the other moving room conditions; significantly higher postural sway variables in the eyes open no VR compared to VR; and significantly higher postural sway variables in the eyes closed no VR compared to VR. This study provides evidence that VR can be used as a safe and low-cost balance training tool by exposing individuals to fall-prone situations and increasing their balance confidence.

While it has been established that postural control is affected by executive function, research is lacking in identifying if specific executive function components are most responsible or if certain aspects of postural control are more affected than others (e.g., proprioception, vestibular, visual). The current study examined the role of inhibition, processing speed, and visuospatial ability in postural control under conditions affecting visual, proprioceptive, and vestibular sensory input. Cognitive assessments consisted of the Flanker Inhibitory Control and Attention Test, Digit Symbol Substitution Test, Clock Drawing Test, Trail Making Test – Part B, and simple reaction time. Standing Balance was used to assess postural sway. Analyses revealed that average balance was significantly associated with simple reaction time (r(88) = -0.31, p < .01) and the clock drawing test (r(88) = -0.25, p< .05). Further analyses revealed a significantly stronger relationship between pose #1 (eyes opened, firm) and average balance (r(88) = -0.845, p< 0.1) when compared to pose #2 (eyes closed, firm), and pose #3 (eyes opened, foam) and average balance r(88) = -0.8015, p< 0.1) when compared to pose #4 (eyes closed, foam). The significantly stronger relationship between these two measures demonstrates that visual input in both conditions #1 and #3 was associated with better postural control. The findings of this study demonstrate that reaction time and visuospatial abilities are associated with overall postural control in healthy older adults. Results suggest that reaction time should be more thoroughly researched to determine the extent of its influence on EF and physical function.

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No description available.

Human upright posture exhibits an everlasting oscillatory behavior of complex nature, called as human postural sway. Variations in the position of the Center-of-Pressure (CoP) were used to describe the human postural sway. In this study / CoP data, which has experimentally been collected from 28 different subjects (14 males and 14 females with their ages ranging from 6 to 84), who were divided into 4 groups according to their ages has been analyzed. The data collection from each of the subjects was performed in 5 successive trials, each of which has lasted for 180-seconds long. Linear analysis methods such as the variance/standard deviation, Fast Fouri&eacute / r Transformation, and Power Spectral Density estimates were applied to the detrended CoP signal of human postural sway. Also the Run test and Ensemble averages methods were used to search for stationarity and ergodicity of the CoP signal respectively. Furthermore, in order to reveal the nonlinear characteristics of the human postural sway, its dynamics were reconstructed in m-dimensional state space from the CoPx signals. Then, the correlation dimension (D2) estimates from the embedded dynamics were calculated. Additionally, the statistical and dynamical measures computed were checked against any significant changes, which may occur during aging. The results of the study suggested that human postural sway is a stationary process when 180-second long biped quiet stance data is considered. In addition, it exhibits variable dynamical structure complex in nature (112 deterministic chaos versus 28 stochastic time series of human postural sway) for five successive trials of 28 different subjects. Moreover, we found that groups were significantly different in the correlation dimension (D2) measure (p&amp / #8804 / 0.0003). Finally, the behavior of the experimental CoPx signals was checked against two types of linear processes by using surrogate data method. The shuffled CoPx signals (Surrogate I) suggested that temporal order of CoPx is important / however, phase-randomization (Surrogate II) did not change the behavioral characteristics of the CoPx signal.

Bakgrund: Nacksmärta är ett vanligt förekommande besvär och en av de främsta orsakerna till att söka vård hos fysioterapeut. Nackbesvär kan leda till förändringar i proprioception, både medveten och omedveten, vilket kan leda till en nedsatt balans. Undersökning av omedveten proprioception har gjorts genom att mäta posturalt svaj vid stimulering av muskelspolar via lokala muskelvibratorer i tidigare studier. Ingen studie har dock undersökt reliabiliteten vid stimulering av nack- och vadmuskler hos personer med respektive utan nacksmärta   Syfte: Studiens syfte var att utvärdera inter-day reliabilitet för posturalt svaj hos personer med eller utan nacksmärta genom att mäta CoP på WBB där deltagarna ges vibrationer på vader, nacke respektive underarmar.   Metod: 50 deltagare deltog i studien, 25 deltagare med nacksmärta och 25 friska kontroller. Deltagarnas CoP mättes på en WBB där deltagarnas förändring av CoP mättes innan, under och efter att vibrationer getts på vader, underarmar respektive nacken. Deltagarna testades vid två tillfällen med 7 dagars mellanrum. ICC2,1 användes för att beräknade relativ reliabilitet. Ett ICC-värde ≥ 0,75 bedöms som god reliabilitet. Absolut reliabilitet beräknades med SEM. Beroende t-test utfördes för att undersöka eventuell systematisk bias såsom adaptioner eller inlärningseffekter mellan testtillfälle 1och 2.   Resultat: Studiens resultat uppvisade en måttlig till utmärkt relativ reliabilitet (ICC = 0,69 - 0,89) för A/P amplituden för hela gruppen och SEM-värden var mellan 0,51 - 1,17 vilket utgör ca 20 - 30% av medelvärdet för de flesta svajvariablerna. En signifikant inlärningseffekt kunde ses för både A/P och M/L amplituden vid vibration av vadmuskulaturen (p = 0,015 - 0,017).   Slutsats: Studiens resultat visar på en acceptabel reliabilitet och testmetoden kan användas i såväl forskning som klinisk användning vid undersökning av posturalt svaj med eller utan vibration. / Background: Neck pain is a common occurrence and one of the main reasons for seeking care at a physiotherapist. Neck disorders can lead to changes in proprioception, both conscious and unconscious, which can lead to a reduced balance. Investigation of unconscious proprioception has been done by measuring postural sway in the stimulation of muscle spindles via local muscle vibrators in previous studies. However, no study has investigated the reliability of stimulation of neck and calf muscles in people with or without neck pain   Purpose: The purpose of the study was to evaluate inter-day reliability on postural sway in people with or without neck pain by measuring CoP on WBB where participants receive vibration on the calf, neck and forearms.   Method: 50 participants participated in the study, 25 participants with neck pain and 25 healthy controls. Participants change of CoP was measured before, during and after vibration was given to calf, forearm and neck. Participants were tested on two occasions at 7-day intervals. ICC2,1 was used to calculate relative reliability. An ICC value ≥ 0.75 is considered to be good reliability. Absolute reliability was calculated with SEM. Dependent t-test was performed to investigate any systematic bias such as adaptations or learning effects between test 1 and 2.   Results: The results of the study showed a moderate to excellent relative reliability (ICC = 0.69 - 0.89) for the A/P amplitude and SEM values ​​were between 0.51 - 1.17 which represents about 20-30% of the mean for most sway variables. A significant learning effect could be seen for both the A/P and M/L amplitude in vibration of the calf muscles (p = 0.015-0.017).   Conclusion: The results of the study demonstrate acceptable reliability and the test method can be used in research and clinical to investigate postural sway with or without vibration.

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No description available.