Motion sickness and postural control among Danish adolescents

Results of the switchgrass co-firing tests conducted at the Ottumwa Generating Station in Chillicothe, Iowa as part of the Chariton Valley Biomass Project. After several years of planning, the Chariton Valley Biomass Project successfully completed two months of switchgrass co-fire testing at the Ottumwa Generating Station (OGS) in Chillicothe, Iowa. From November 30, 2000, through January 25, 2001, the switchgrass team co-fired 1,269 tons (1,151 tonnes) of switchgrass at rates up to 16.8 tons/h (15.2 tonne/h), representing about 3% heat input to the 725-MW power plant. Stack testing was completed when co-firing switchgrass and when burning only coal. Fuel and ash samples were collected for analysis, and boiler performance and emissions data were collected. Numerous improvements were made to the feed-handling equipment during testing. The co-fire testing was completed with no environmental incidents, no injuries to personnel, and no loss in electricity output from OGS. The goals of the this--the first of three rounds of co-fire tests--were: to identify the effects of co-firing on boiler performance, to measure any changes in emissions during co-firing, and to gather information to improve the design of the switchgrass handling equipment. All three of these goals were met. The design target for the switchgrass handling system was 12.5 ton/h (11.3 tonne/h), which we exceeded after a redesign of the secondary grinder in our system. We had hoped to burn over 3,000 tons (2,722 tonnes) of switchgrass during this first round of testing, but because of poor equipment performance in December, we were unable to meet this target before the planned boiler shutdown in January. There were, however, several days in January when we burned more than 100 tons (91 tonnes) of switchgrass.

Motion sickness is defined as a sensation of uneasiness that occurs during physical motion, such as transportation by bus, plane, car or train. Postural control is one of the multisensory processes that has been examined in individuals susceptible to motion sickness. Indeed, postural control relies on visual, somatosensory and vestibular information. While studies suggest normal-like postural control during quiet standing, others suggest that individuals with motion sickness show increased postural instability during sensory perturbations, namely during visual and somatosensory disturbances. The impact of vestibular stimulation on postural control in individuals with motion sickness has yet to be determined. Therefore, the aim of the present exploratory study was to examine the effects of sinusoidal electrical vestibular stimulation on postural control in individuals with varying degrees of motion sickness. Fifty participants were divided into three groups based their susceptibility to motion sickness. Participants were initially tested at baseline in the four postural conditions of the modified Clinical Test of Sensory Integration and Balance protocol (mCTSIB): eyes open on firm surface, eyes closed on firm surface, eyes open on foam surface, eyes closed on foam surface. These four conditions were then repeated during sinusoidal electrical vestibular stimulation (EVS) of 1mA at 1Hz. In baseline conditions, no significant group differences in postural control were found. Data in experimental (EVS) conditions, however, suggests that individuals with high susceptibility to motion sickness are more impacted by vestibular stimulation, specifically in the eyes closed on firm surface condition. It has been suggested that motion sickness could be the result of an altered multisensory integration process. While the present data do not allow us to answer this question, it would remain important to examine all types of sensory perturbations and combinations thereof in a larger group of individuals.

Static posturography is a simple non-invasive technique commonly used in contemporary labs and clinics to quantify the central nervous system adaptive mechanisms involved in the control of posture and balance. Its diagnostic value, however, is quite limited due to the lack of posturographic standards for the stable posture. To solve this problem, in this research, we aimed to establish reference values for the stable human posture using our novel parameters of static posturography including the sway anteroposterior directional index (DIAP), the mediolateral directional index (DIML), the stability vector amplitude (SVamp), and the stability vector azimuth (SVaz). Towards this end, in a population of young (mean age 22 yrs), healthy able-bodied volunteers (50 males and 50 females), trajectories of postural sway, based upon the center-of-pressure (COP), were assessed. The experiment consisted of ten 60 s trials that were carried out 5 times while subjects were standing quietly on the force plate with eyes open (EO test) and 5 times with eyes closed (EC test). Results showed that in young healthy subjects, regardless of gender, the basic variables of COP remained at the following levels: SVamp = 9.2 ± 1.6 mm/s, SVaz = 0.9 ± 0.1 rad, and directional indices DIAP = 0.7 ± 0.05, DIML = 0.56 ± 0.06. Some of the measures were sensitive to visual input (EC trials), and showed a weak to moderate correlation with anthropometric features. These measures can be recommended as reference values that characterize the most stable erect posture.

Effects of assistive devices on postural control following a balance disturbance along the anterior-posterior direction.

We performed two experiments to investigate the relationship between motion sickness and active or passive posture control. Experiment 1: Coriolis stimulation evokes not only motion sickness but also nystagmus and body sway. Eight subjects were asked to execute head tilt with eyes open or eyes covered while standing on a force-platform attached to a turntable. Eye movements were recorded using an infrared CCD camera. The center of pressure was recorded simultaneously. While gaze and posture became passive conditions and motion sickness was evoked with eyes covered, the subjects could maintain active control of posture and motion sickness was not evoked with eyes open. Experiment 2: Head tilt angle while riding in a car recorded on videotapes was quantitatively evaluated by computer analysis. While head movements of passengers became unstable and motion sickness was evoked, the head of the driver always tilted in the same direction as the curve and motion sickness was not evoked. Motion sickness appeared when the head returned from the tilted position to the original position. These results suggest that spatial orientation (the perception of the spatial relationship between self and the outer world) determines whether posture control will be active or passive, and whether motion sickness will be evoked.

Aging is associated with impairment in postural control in humans. While dogs are a powerful model for the study of aging, the associations between age and postural control in this species have not yet been elucidated. The aims of this work were to establish a reliable protocol to measure center of pressure excursions in standing dogs and to determine age-related changes in postural sway. Data were obtained from 40 healthy adult dogs (Group A) and 28 senior dogs (Group B) during seven trials (within one session of data collection) of quiet standing on a pressure sensitive walkway system. Velocity, acceleration, root mean square, 95% ellipse area, range and frequency revolve were recorded as measures of postural sway. In Group A, reliability was assessed with intraclass correlation, and the effect of morphometric variables was evaluated using linear regression. By means of stepwise linear regression we determined that root mean square overall and acceleration in the craniocaudal direction were the best variables able to discriminate between Group A and Group B. The relationship between these two center-of-pressure (COP) measures and the dogs’ fractional lifespan was examined in both groups and the role of pain and proprioceptive deficits was evaluated in Group B. All measures except for frequency revolve showed good to excellent reliability. Weight, height and length were correlated with most of the measures. Fractional lifespan impacted postural control in Group B but not Group A. Joint pain and its interaction with proprioceptive deficits influence postural sway especially in the acceleration in the craniocaudal direction, while fractional lifespan was most important in the overall COP displacement. In conclusion, our study found that pressure sensitive walkway systems are a reliable tool to evaluate postural sway in dogs; and that postural sway is affected by morphometric parameters and increases with age and joint pain.

Plegic limb classification using cluster analysis

Neurodevelopmental treatment (NDT) and Dynamic neuromuscular stabilization (DNS)-based exercise is effective for improving core stability and postural control in stroke patients. To compare the effects of DNS and conventional NDT exercises on diaphragm movement, abdominal muscle thickness, and postural control in stroke patients. The participants were randomly allocated into DNS (n = 16) and NDT (n = 15) for 30 minutes each per day, 3 days a week for 4 weeks. Diaphragm movement and abdominal muscle thickness were determined using ultrasonography. The trunk impairment scale (TIS) and Berg Balance Scale (BBS) were used to measure postural control. The functional ambulation category (FAC) was used to evaluate gait ability. Analysis of covariance (ANCOVA) was used to evaluate post-test differences in the DNS and NDT exercise groups. ANCOVA revealed the superior effects of DNS in diaphragm movement and abdominal muscle thickness (transversus abdominis, internal oblique), as well as clinical BBS and FAC tests, compared with those of NDT (p < 0.05). This novel clinical trial suggests that DNS training was more effective than NDT training in improving postural movement control and gait ability via a balanced co-activation of the diaphragm and TrA/IO in stroke patients.

Context-dependent coupling of posture, gait, and functional mobility under cognitive and sensory demands in Parkinson's disease.

This study aimed to determine if pain and balance control are related to meteorological modifications in patients with knee osteoarthritis (OA). One hundred and thirteen patients with knee OA (mean age=65±9years old, 78 women) participated in this study. Static posturography was performed, sway area covered and sway path traveled by the center of foot pressure being recorded under six standing postural conditions that combine three visual situations (eyes open, eyes closed, vision altered) with two platform situations (firm and foam supports). Knee pain score was assessed using a visual analog scale. Balance control and pain measurements recorded in the morning were correlated with the meteorological data. Morning and daily values for temperature, precipitation, sunshine, height of rain in 1h, wind speed, humidity, and atmospheric pressure were obtained from the nearest data collecting weather station. The relationship between postural control, pain, and weather variations were assessed for each patient on a given day with multiple linear regressions. A decrease of postural stability was observed when atmospheric pressure and maximum humidity decreased in the morning (p<0.05) and when atmospheric pressure decreased within a day (p<0.05). Patient's knee pain was more enhanced when it is warmer in the morning (p<0.05) and when it is wetter and warmer within a day (p<0.05). The relationship between weather, pain, and postural control can help patients and health professionals to better manage daily activities.

This case report aims to raise a physiotherapy intervention for subjects with SMS. The basis is an active work, based on postural control and balance training. Physiotherapists can play an important role in the management of these subjects. Smith-Magenis syndrome (SMS) is a genetic alteration that encompasses a series of psychophysical repercussions that interferes with postural control and the autonomous functionality of the subjects who suffer from it. In this study, a clinical case of an 18-year-old adolescent with a genetic diagnosis of an SMS mutation is presented. This work proposes a physiotherapy intervention, adapted to the individual conditions and agreed upon with his family. The goal would be to analyze the effectiveness of postural control and balance training in a subject with SMS. A physiotherapy intervention based on postural control and balance was proposed. This approach is combined with the strengthening and readaptation of the antigravity muscles, through strength training, mobilization exercises, gait and transfers reeducation. An initial assessment was carried out. The interventions were developed at the home of the clinical case. The main variables were balance and postural control. For this, the following measurement scales and tests were used: Face Scale, Gross Motor Function Scale, Berg Balance Scale, Romberg Test, Barthel Index, and Functional Assessment of Sitting (SATco scale). After the intervention, the case presented under observation greater postural control in the transfers, less imbalances, and introduced new positions during their development, which allow more functional and autonomous movement. This was also extrapolated to gait, which was optimized in its development. This observation was not reflexed in test scores, which remained the same than the initial assessment. The intervention had a positive effect on the development of trunk control, transfers, and gait.

BackgroundPostural instability is a debilitating cardinal symptom of Parkinson’s disease (PD). Its onset marks a pivotal milestone in PD when balance impairment results in disability in many activities of daily living. Early detection of postural instability by non-expensive tools that can be widely used in clinical practice is a key factor in the prevention of falls in widespread population and their negative consequences.ObjectiveThis study aimed to investigate the effectiveness of a two-dimensional balance assessment to identify the decline in postural control associated with PD progression.MethodsThis study recruited 55 people with PD, of which 37 were men. Eleven participants were in stage I, twenty-three in stage II, and twenty-one in stage III. According to the Hoehn and Yahr (H&amp;amp;Y) rating scale, three clinical balance tests (Timed Up and Go test, Balance Evaluation Systems Test, and Push and Release test) were carried out in addition to a static stance test recorded by a two-dimensional movement analysis software. Based on kinematic variables generated by the software, a Postural Instability Index (PII) was created, allowing a comparison between its results and those obtained by clinical tests.ResultsThere were differences between sociodemographic variables directly related to PD evolution. Although all tests were correlated with H&amp;amp;Y stages, only the PII was able to differentiate the first three stages of disease evolution (H&amp;amp;Y I and II: p = 0.03; H&amp;amp;Y I and III: p = 0.00001; H&amp;amp;Y II and III: p = 0.02). Other clinical tests were able to differentiate only people in the moderate PD stage (H&amp;amp;Y III).ConclusionBased on the PII index, it was possible to differentiate the postural control decline among the first three stages of PD evolution. This study offers a promising possibility of a low-cost, early identification of subtle changes in postural control in people with PD in clinical practice.

Partial or total unilateral vestibular loss is the third most common cause of peripheral vestibular dysfunction. Dysfunction of one or both of the vestibular mechanisms can manifest physically as abnormalities of posture, balance, and/or visual acuity. This case report describes physical therapy examination and individualized intervention with vestibular rehabilitation for a patient with unilateral vestibular hypofunction. The patient was an 80-year-old male with electronystamographically confirmed unilateral vestibular loss of 98.3%. He demonstrated altered balance and gaze stability classifying him as having an increased risk for falling. After 5 weeks of individualized vestibular rehabilitation, the patient significantly decreased his fall risk from 11 to 20 of 24 on the Dynamic Gait Index. His gaze stability also improved from a 4 to 1 line disparity with dynamic visual acuity testing. The patient also had a decrease in perceived disability on the Dizziness Handicap Inventory from 30/100 at evaluation to 12/100 at discharge. Individualized vestibular rehabilitation decreased fall risk and improved gaze stability for a patient with significant unilateral vestibular hypofunction.

Multiple Sclerosis is a chronic autoimmune disease affecting the central nervous system, leading to progressive motor dysfunction and balance deficits. Balance impairments were evident as one of the earliest signs of the disease with a substantial majority of Multiple Sclerosis (MS) patients, between 50% and 80%, exhibiting signs of abnormalities in postural control and gait shortly after diagnosis. Although disease-modifying therapies have advanced, there remains an unmet need for effective treatments that target motor and cognitive impairments. The Purpose of the study: was to investigate the impact of cerebellar high frequency repetitive Transcranial Magnetic Stimulation in improving postural control, balance and functional ambulation in individuals with Multiple Sclerosis. Of the 40 patients with multiple sclerosis, the group receiving cerebellar Real repetitive Transcranial Magnetic Stimulation (rTMS) showed significant reduction in the Expanded Disability Status Scale and the International Cooperative Ataxia Rating Scale. This group also showed significant improvement in balance performance and gait speed, evident by the results of Center of Pressure measurement under both eyes open and eyes closed conditions, assessed by static posturography. The 10-meter walk test also showed significant improvements in comparison to the control group who received sham rTMS. Cerebellar rTMS is a promising therapeutic tool for addressing motor and balance dysfunction in MS. Its inclusion in comprehensive rehabilitation programs may enhance the functional independence for patients affected by this challenging condition.

ObjectiveForce platforms are widely used to assess postural stability and fall risk in older adults. However, traditional parameters often capture overlapping phenomena and fail to fully reflect underlying control mechanisms. This study evaluated combining of six partly independent parameters to distinguish sex and age-related differences in postural control among community-dwelling elderly.MethodsA total of 4,588 adults aged 65–95 years were assessed using static posturography under non-visual conditions. Six time-domain parameters, reflecting torque control, positional control and anticipatory control of the center point of force. Romberg’s quotient was included for comparison.ResultsFemales exhibited greater stability, whereas males relied more on corrective force moments and showed larger sway amplitudes. Classification trees predicted sex with 71% accuracy using three parameters. Aging was associated with increased anteroposterior sway amplitude and a reduction in the critical time for transition between open- and closed-loop control. Additional age-sensitive parameters included mediolateral velocity zero-crossing rate and steady-phase duration. Age could be predicted within ±5 years for both sexes. Romberg’s quotient could discriminate age in 30% and sex differences in 60% of participants, only.ConclusionPostural stability is influenced by both sex and age. The identified combination of parameters provides a framework for estimating the “biological age” of postural control and investigate balance impairments. Age-related decline appears consistent within a 5-year range, bur does not exclude the effect of lifestyle or comorbid factors. This study demonstrates that use of multidimensional data vectors with the implementation of AI-modeling can improve the predictive accuracy and clinical applicability of posturography.