Body sway in tilting condition

〔目的〕パーキンソン病患者における立位時足圧中心の前後移動量と足圧分布の関連について調べた．〔対象〕パーキンソン病患者8名と健常高齢者8名が参加した．〔方法〕足圧分布計上で体幹前後動揺を行った．足趾部・中足骨部・踵部の荷重圧変化を独立変数，足圧中心の移動変化を従属変数とした重回帰分析を行い，偏回帰係数を算出した．〔結果〕パーキンソン病患者は健常群と比較して足長に対する足圧中心の移動比率が前後共に低下し，偏回帰係数は足趾部で有意に低く，中足骨部で有意に高かった．〔結語〕パーキンソン病患者における立位時の随意的な前方への足圧中心移動量の低下は，足趾部への荷重量低下に起因する．

Following a lesion in the vestibular system visual, proprioceptive and residual vestibular information is integrated by the brain, to enable a patient to attain equilibrium. The basis of vestibular rehabilitation is to encourage these adaptive and compensatory mechanisms. Another form of rehabilitation is to provide some form of mechanical aid, and walking sticks are often used for this purpose in patients with balance disorders. There are no reported studies objectively assessing the use of walking sticks in patients with balance disorders. In this study we used the Sway Weigh balance platform (Raymar) to determine the efficacy of a walking stick in 25 patients with peripheral vestibular balance disorders. Patients were tested with their eyes opened and eyes closed whilst they were standing on a flat surface and on an air-filled bed (to alter limb proprioception) on the Sway Weigh balance platform. All the tests were carried out with, and without, a walking stick. The results demonstrate that a walking stick significantly reduces lateral body sway in patients with peripheral vestibular balance disorders.

In 1983, the board of the Japan Society for Equilibrium Research presented a standard of stabilometry, but some problems remain.In order to determine the test conditions, we performed the following examination with a standard stabilometer.1 . For visual target testing, the distance from the subject to the target and the illumination of the peripheral visual field were studied.2. For the standing posture, body sway in the military standing posture was compared with that in natural standing.3. For foot position, body sway while standing with both feet together was compared with that feet in the fan-shaped position and with feet apart but parallel.4. For recording time, body sway while standing for 30 seconds was compared with that while standing for 60 seconds.5. To elimilinate transitional sway after standing erect with eyes closed, the time when the recording should start was studied.The parameters for stabilometry are as follows ; unit locus lengh, forward-backward and right-left diameters, area, rejection ellipse, center of sway, standard deviation, skewness and kurtosis of amplitude probability density distribution, velocity, vector of velocity, power spectrum.1. When the visual target was placed one meter from the subject and the peripheral field of vision was lighted, the mean and standard deviation of all parameters in stabilometry were the smallest.2. Standard deviations of the unit locus length, area and velocity during military posture standing were lower than during natural standing. However, maintenance of military standing for 60 seconds was difficult. Therefore, stabilometry with natural standing was considered more suitable for clinical examinations.3. Body sway while standing with feet 10 cm apart was less than when standing with the feet close together or in the fan-shaped position. However, standing with the feet close together was suitable for detecting slight equilibrium disturbances.4. Body sway observation for 60 seconds clarified the pattern of the body sway more definitely than did observation for 30 seconds.5.Irregular sway was recorded after the subject stood erect with eyes closed for 10 seconds. To eliminate transitional sway, the recording should be started when the body movements of the standing subject are stabilized.

This study examined the interrelationships between various parameters evaluating body sway from the center of foot pressure (CFP) during a static standing posture, and gender difference by domain. The subjects were 220 healthy young males and females. CFP was measured 3 times with a 1 min rest, and the mean of trials 2 and 3 was used for the analysis. The measurement device was Anima's stabilometer G-5500. Data sampling frequency was 20Hz. Sixty parameters with higher reliability were selected from the following 7 domains: distance, center average, distribution of amplitude, area, velocity, power spectrum, and body sway vector.Several parameters showed a significant gender difference, but the degree was not large. The correlation coefficients between parameters in each domain of distance, center average, distribution of amplitude, area, velocity, and body sway vector were very high, and they tended to relate closely to some parameters in the other domains. Gender difference in the correlation coefficient was insignificant. Therefore, the relationship between parameters in both genders was judged to be very similar.After examining the interrelationship between parameters, 36 parameters were selected. We judged that the body sway can be synthetically evaluated by these rather than 60 parameters.

Viewing angle effects from wide field video projection images on the human equilibrium

The body sway of the patients with unilateral and bilateral Meniere's disease was recorded by using a cephalograph and a stabilometer, and analyzed with a microcomputer.The results show that the locus type, locus area and locus length traced by the head's center and the body's center of gravity (abbreviated to CG) are useful parameters of the body sway, representing the characteristics of peripheral vestibular disorders. The noteworthy characteristics are shown in the left and right type in statokinesigram, the significant differences of locus area and/or locus length between the head movement and the CG movement, high degree of cross-correlation between the head movement and the CG movement, and the change of the averaged divisional frequencies of the body sway with eye-closing.

Crosstalk opposing view: Fear of falling does not influence vestibular-evoked balance responses.

Optic flow-induced sway in anxiety disorders associated with space and motion discomfort

In previous studies, many evaluation parameters for the center of foot pressure (CFP) in a static standing posture have been proposed, but their reliability and inter-relationships have not been sufficiently examined.The purposes of this study were to examine trial-to-trial reliability and the inter-relationships of various evaluation parameters and to propose useful ones. Thirty healthy young adults were selected as subjects. The measurement of CFP for 1 minute was carried out 10 times with 1 minute rest for each subject. The measurement device was an Anima's stabilometer G5500. The data was recorded every 20 msec. Seventy-six evaluation parameters, excepting composite parameters from 114 parameters proposed in previous studies, were selected from the following domains: distance, center of pres-sure, distribution of amplitude, area, velocity, power spectrum, and vector for body sway. The intraclass correlation coefficients (ICC) for 10 trials were 0.7 or over for all parameters excepting for the X-axis and the Y-axis distribution for body sway, and skewness and kurtosis for body sway speed, but a significant difference between the first trial and the other trials was found in many parameters. Therefore, the ICC was recal-culated by excluding the first trial. As a result, no significant difference was found other than that of the distance of the root of the mean square and the area of the root of the mean square. The ICC was 0.7 or over, excepting for the following parameters: the X-axis and the Y-axis distribution for body sway and skewness and kurtosis for body sway speed, the cross correlations for body sway and body sway speed, the C ratio of the power spectrum area on the X-axis, the A ratio of the power spectrum area on the Y-axis and the root of the mean square-axis. Inter-correlation coefficients between parameters in each domain of distance, center of pressure, distribution of amplitude, area, velocity, power spectrum, and vector for body sway were mostly high values of 0.9 or over. Thus, it was considered that there is a close relationship between theoretically similar parameters and any of them could be selected as useful parameters.Based on the above-stated examination, 60 evaluation parameters shown in Table 5 were finally selected.

This study was done to examine age-stage (preschool children, young adults, and elderly people) differences in the center-of-pressure sway using body-sway factors (unit-time sway, front-back sway, left-right sway, and high frequency-band power), power-spectrum distribution, and relative accumulation of power frequency (25%, 50%, and 75% RAPF) of the center-of-pressure spectrum. The center-of-pressure movement for 1 min. was measured twice using Anima's stabilometer. Data-sampling frequency was set at 20 Hz. Significant age-stage differences were found for 3 factors except for left-right sway, which was larger for preschool children and elderly than for young adults. The power spectrum of body sway in any age-stage was noted mainly in low frequency bands. A marked age-stage difference was found at 75% RAPF. Body-sway characteristics in each age-stage differ, and differences of postural-sway frequency are marked in the low frequency bands.

Postural stability is an important measure for many medical diseases such as Parkinson. In the last years, research focused on using inexpensive and portable devices to measure postural stability, while the visual targets were physical objects in the environment. Sensing balancing boards were used to measure stance forces, while movements of the upper body were not taken into account. Within this paper, postural stability was measured using the HTC Vive. A variation of a virtual fixation point's distance was analyzed and compared to a reference condition with closed eyes. It is shown that body sway in the VR conditions is increased in the anterior-posterior and decreased in the medial-lateral direction.

In recent years, an increasing number of university students are found to be at high risk of depression. Through a large scale depression screening, this paper finds that around 6.5% of the university postgraduate students in China experience depression. We then investigate whether the gait patterns of these individuals have already changed as depression is suggested to associate with gait abnormality. Significant differences are found in several spatiotemporal, kinematic and postural gait parameters such as walking speed, stride length, head movement, vertical head posture, arm swing, and body sway, between the depressed and non-depressed groups. Applying these features to classifiers with different machine learning algorithms, we examine whether natural gait analysis may serve as a convenient and objective tool to assist in depression recognition. The results show that when using a random forest classifier, the two groups can be classified automatically with a maximum accuracy of 91.58%. Furthermore, a reasonable accuracy can already be achieved by using parameters from the upper body alone, indicating that upper body postures and movements can effectively contribute to depression analysis.

• Several lines of evidence suggest a possible role of 5-HT(6) receptor antagonists in dementia or cognitive dysfunction of schizophrenia. SB-742457 is a potent 5-HT(6) antagonist and has shown efficacy in different animal models of cognitive impairment. It is currently in development as a cognitive enhancer. Risperidone, commonly used to control agitation and psychotic features in both schizophrenia and Alzheimer's disease, is a D(2)/5-HT(2A ) antagonist with low affinity for 5-HT(6) receptors and limited effects on cognitive parameters. • As the combination of risperidone and SB-742457 may constitute a reasonable combination in cognitively impaired patients, pharmacodynamic interaction effects were investigated in this study. The only significant drug-drug interaction was a small increase of electroencephalogram (EEG) alpha and beta bands, which might suggest mild arousing activity of SB-742457 on the central nervous system-depressant effects of risperidone. The clinical relevance of these findings in patients remains to be established. Additionally, this study provided an extensive multidimensional pharmacodynamic profile of risperidone in healthy volunteers, showing that this antipsychotic suppresses motor performance (eye-hand coordination, finger tapping and postural stability), alertness, memory and neurophysiological functions (saccadic eye movements and EEG power spectrum). Several lines of evidence suggest a possible role of 5-HT(6 ) receptor antagonists in cognitive dysfunction of schizophrenia. Atypical antipsychotics, such as risperidone, are currently used in these disorders. Therefore, the pharmacological interactions between the 5-HT(6) antagonist SB-742457 and risperidone were investigated in the light of possible co-medication. A randomized, double-blind, two-way crossover design was used to study the interaction between multiple doses SB-742457 50 mg and a single dose risperidone 2 mg in 18 healthy subjects. Treatment was well tolerated. The most common adverse event was somnolence in 83% during the combination vs. 50% of subjects after risperidone, 32% after placebo and 11% after SB-742457. Combination treatment produced a statistically significant increase in the maximum plasma concentration of risperidone and had no effect on SB-742457 pharmacokinetics. Risperidone decreased saccadic peak velocity, finger tapping, adaptive tracking, subjective alertness, delayed word recognition and body sway and increased electroencephalogram (EEG) theta power and prolactin. The only pharmacodynamic interaction of risperidone and SB-742457 was an increase of absolute EEG alpha (ratio = 1.25, 95% CI = 1.11, 1.40, P= 0.0004) and beta power (ratio = 1.14, 95% CI = 1.03, 1.27, P= 0.016). No significant effects of SB-742457 alone were found. The pharmacokinetic interactions between SB-742457 and risperidone detected in this study were not clinically relevant. The increase in EEG alpha and beta power is incompatible with enhanced risperidone activity, but could point to mild arousing effects of the combination. Most pharmacodynamic changes of risperidone are consistent with previously reported data. The potential cognitive effects of SB-742457 remain to be established.

Seiza is one of the most commonly used sitting postures in various enrichment lessons of Japanese origin. It is reported that Seiza with large knee flexion produces harmful effects on the cartilage of knee joints and hemodynamics of the lower legs. This study aimed at examining the influence of Seiza on tissue oxygenation kinetics of the lower limbs, plantar somatic and cutaneous sensation, and the center of foot pressure (COP) sway using 10 young adults. COP sway was measured for 1 min just after sitting on a chair for 10 min (pre-test), after 30-min Seiza (post-test 1), and 5 min after Seiza (post-test 2). To evaluate the COP sway, we used 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3) and high frequency band power spectrum factor (F4). Physiological parameters (i.e., tissue oxygenation kinetics in the lower legs and sensation on the sole) were measured during 30-min Seiza (continuously on tissue oxygenation, and at 1 min intervals on sensation), and for 1 min just before each COP test (pre-test, post-test 1 and 2). Oxygenated hemoglobin/myoglobin (Hb/Mb) concentration decreased markedly and deoxygenated Hb/Mb concentration increased markedly, resulting in reaching a plateau state at around 7 min. Tissue Hb/Mb index changed little during Seiza. Proprioceptive perception thresholds increased rapidly about 17 min after Starting Seiza. Means of 3 COP sway factors of F1, F2 and F4 were significantly higher in post-test 1 than in pre-test and post-test 2. In conclusion, a marked decrease in tissue oxygen concentration of the lower legs within 4-5 min, and an increase of proprioceptive perception thresholds in the sole at about 17 min are induced by Seiza. Although wiggle and quick body sway in the antero-posterior axis increases markedly in an upright posture just after maintaining Seiza for 30 min, sway recovers after sitting on a chair for 5 min.

Serrations, which imitate the sawteeth-like structures in the leading edge of owl wing, enable to reduce noises and alter the aerodynamic performance. However, the mechanism is not yet completely understood because the flow fields have three-dimensionality. In this study, in order to investigate three-dimensional mean flow structures on a flat plate with leadingedge serrations, flow fields viewed from the spanwise and vertical directions were measured by two-dimensional time-resolved PIV and stereo PIV at the Reynolds number of 5.0×10. When the angle of attack was 6 degree, the interval of the flow pattern was equal to the width of one sawtooth of the serrations. Whereas the flow over the trough was separated, and the flow over the vertex passed along the surface of the flat plate. This is because pairs of longitudinal vortices induced by the serrations suppress the flow over the vertex on the uppersurface of the flat plate. When the angle of attack was 14 degree, several flows over the vertexes were gathered, and specific flow patterns were formed. The flow over the vertex passed along the surface of the flat plate, so that separation points viewed from the spanwise direction moved to the downstream side. Reverse-flow regions behind the troughs could be divided into two categories, “open” and “closed” ones. Pairs of longitudinal vortices were seen in the closed reverse-flow regions only, and growth of the open reverse-flow regions forces the vortices to move upwards.