No description available.

The somatosensory system has been implicated in the compensatory response of the nervous system to postural perturbations in humans and cats. The approach elicited - dubbed the Force Constraint Strategy - through a possible combined action of proprioceptive and cutaneous feedback, determines, and adjusts for, horizontal disturbances in various directions of a supporting surface. To understand the mechanisms underlying this strategy, we asked whether the response patterns of muscle proprioceptors correspond to those of electromyographic recordings (EMG) in the aforementioned Force Constraint experiments. The mechanical properties of the musculoskeletal system may also play a role in the restoration of stability. Thus, we also hypothesize that a proximal muscle would be relatively tightly tuned spatially whereas the distal muscle would exhibit a more diffuse spatial response distribution. To this end we selected the medial gastrocnemius (MG) and biceps femoris (BF) muscles to serve as our proximal and distal models respectively. Cats anesthetized using pentobarbital were set in a stereotaxic frame with the right leg positioned on a servo-controlled platform. The platform was shifted horizontally in 16 different directions according to a ramp-and-hold waveform. Intra-axonal recordings of activity from Ia afferents of BF and MG muscles were taken. Results indicate that the strategy makes use of information from the muscle proprioceptors. However, there is no differential response in tuning breadth with respect to muscle architecture. By characterizing the role of muscle proprioceptors in the mediation of corrective responses to perturbations of balance and stability, the results from this experiment can be used to verify biomechanical models, as well as further elucidate the underlying mechanisms of motor control.

Developmental delays are known to exist in children with autism when compared to their typically developing peers. Foundations of these delays stem from the cognitive and motor performance realm, but information regarding specific characteristics, such as postural stability and sensory integration, are less defined. In this study, postural stability differences were investigated between children with autism and neurotypical children. Past research has shown the role of sensory integration during postural sway has been a strong indicator in showing developmental progress. Due to the focus of the protocol being on static balance, the Modified-Central Test of Sensory Interaction for Balance was used to measure postural stability. The age range for this study is set between 3 and 5 years of age and follows CTSIB protocol to assess 32 neurotypical developing children and compare their results to an archived data set containing CTSIB results from a sample of children with autism. Results from the study indicate that when the autism and neurotypical groups were compared, no significant main effect was found. Developmental differences were found across age groups in that 5 year olds displayed more stability than 4 year olds, but there was no difference between 3 and 4 year olds or 3 and 5 year olds. Further analyses of these developmental results indicated that children in the neurotypical group follow an expected developmental progression while children in the autism group display a divergence from this typical progression. Findings of this research add to the existing literature that children with autism display inconsistent developmental patterns which have a strong relationship with the delayed activity levels of these children. The knowledge and understanding of these delays will allow practitioners to implement specially designed programs to ensure that these children receive the activity that they need and deserve. / text

Os estudos realizados até o momento demonstram que os instrumentos descritos na literatura possuem pouca capacidade de identificar os indivíduos em risco de quedas e portanto, existe a necessidade do desenvolvimento de novos testes ou de uma bateria de testes para essa população. Este estudo teve como objetivo traduzir e validar a Escala de Equilíbrio e Marcha (GABS) para aplicação em pacientes com doença de Parkinson (DP), determinar as características clínicas que estariam associadas ao maior risco de quedas em pacientes com DP e sujeitos saudáveis e analisar a utilidade do teste de Estabilidade Postural para avaliar o risco de quedas nos pacientes com DP. Foram selecionados pacientes do Ambulatório de Distúrbios do Movimento (AEXP) do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, com diagnóstico de DP e controles saudáveis. Os participantes foram avaliados por meio da versão motora simplificada da UPDRS, escalas de HY, SE, FOGQ, FES-I, BBS e GABS. Fizeram parte do estudo 107 pacientes com DP e 80 controles e pode-se verificar que a versão brasileira da GABS mostrou ser válida e confiável, com ótima consistência interna e boa confiabilidade inter e intraexaminador. Além disso, obteve validade convergente consistente, com correlações boas com outros instrumentos que avaliam o mesmo conceito. Somado a esses resultados, a GABS teve boa acurácia, sensibilidade, especificidade, valor preditivo positivo e valor positivo negativo considerável. Quando a GABS foi comparada com a BBS, as duas escalas tiveram resultados semelhantes. Entretanto, a GABS mostrou ser uma escala mais completa que a BBS, pois avalia diversos aspectos relacionados ao risco de quedas, como a instabilidade postural, alterações na marcha, o freezing e o medo de quedas, mostrando ser um instrumento mais interessante de ser utilizado em futuros ensaios clínicos e estudos prospectivos de evolução clínica da doença. Com relação às quedas, o principal ambiente relacionado às quedas nos pacientes com DP foi o doméstico e a marcha a principal causa, já nos controles o principal local das quedas também foi o doméstico e a principal causa de quedas foram os obstáculos presentes no ambiente. Além disso, maior tempo de doença e maior medo de quedas foram os fatores que mais contribuíram para explicar as quedas da população com DP. O teste de Estabilidade Postural conseguiu diferenciar os indivíduos com DP que sofreram quedas dos que não sofreram quedas, obteve correlações significativas com outros instrumentos que avaliam o equilíbrio e teve boa confiabilidade interexaminador. / Most studies to date have shown that the instruments available for the assessment of fall risk are inadequate for the identification of vulnerable individuals. Therefore, new tests assessing fall risk are strongly needed. This study aimed to translate and validate the Gait and Balance Scale (GABS) for use in patients with Parkinson\'s disease (PD), describe the clinical characteristics of a sample of patients with PD and controls that are related to the fall risk and analyze the Postural Stability test and it validity for assessing fall risk in patients with PD. We selected 107 PD patients at the Movement Disorders Outpatient Clinic of the School of Medicine of Ribeirão Preto - Universidade de São Paulo (USP) and 80 healthy controls. Participants were evaluated using the simplified version of the UPDRS motor scale, HY, SE, FOGQ, FES-I, BBS, and GABS. The Brazilian version of the GABS showed to be valid and reliable, with excellent internal consistency and good test-retest reliability. Furthermore, satisfactory convergent validity with other instruments that assess the same construct was found. In addition to these results, the GABS had good accuracy, sensitivity, specificity, positive predictive value, and negative predictive value. When the GABS was compared with the BBS, the two scales had similar results. However, the GABS showed to be more complete and could analyze more aspects related to fall risk in PD, as postural instability, gait deficits, freezing and fear of falling. Among controls, most falls also occurred indoors, however, they were mostly related to environmental hazards, and not gait. Longer disease duration and greater fear of falling were the factors that most contributed to explain falls in the population with PD. The Postural Stability test is able to differentiate individuals with PD who had experienced falls from those who had not, had significant correlation with others balance instruments and had good interexaminer reliability.

Os estudos realizados até o momento demonstram que os instrumentos descritos na literatura possuem pouca capacidade de identificar os indivíduos em risco de quedas e portanto, existe a necessidade do desenvolvimento de novos testes ou de uma bateria de testes para essa população. Este estudo teve como objetivo traduzir e validar a Escala de Equilíbrio e Marcha (GABS) para aplicação em pacientes com doença de Parkinson (DP), determinar as características clínicas que estariam associadas ao maior risco de quedas em pacientes com DP e sujeitos saudáveis e analisar a utilidade do teste de Estabilidade Postural para avaliar o risco de quedas nos pacientes com DP. Foram selecionados pacientes do Ambulatório de Distúrbios do Movimento (AEXP) do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, com diagnóstico de DP e controles saudáveis. Os participantes foram avaliados por meio da versão motora simplificada da UPDRS, escalas de HY, SE, FOGQ, FES-I, BBS e GABS. Fizeram parte do estudo 107 pacientes com DP e 80 controles e pode-se verificar que a versão brasileira da GABS mostrou ser válida e confiável, com ótima consistência interna e boa confiabilidade inter e intraexaminador. Além disso, obteve validade convergente consistente, com correlações boas com outros instrumentos que avaliam o mesmo conceito. Somado a esses resultados, a GABS teve boa acurácia, sensibilidade, especificidade, valor preditivo positivo e valor positivo negativo considerável. Quando a GABS foi comparada com a BBS, as duas escalas tiveram resultados semelhantes. Entretanto, a GABS mostrou ser uma escala mais completa que a BBS, pois avalia diversos aspectos relacionados ao risco de quedas, como a instabilidade postural, alterações na marcha, o freezing e o medo de quedas, mostrando ser um instrumento mais interessante de ser utilizado em futuros ensaios clínicos e estudos prospectivos de evolução clínica da doença. Com relação às quedas, o principal ambiente relacionado às quedas nos pacientes com DP foi o doméstico e a marcha a principal causa, já nos controles o principal local das quedas também foi o doméstico e a principal causa de quedas foram os obstáculos presentes no ambiente. Além disso, maior tempo de doença e maior medo de quedas foram os fatores que mais contribuíram para explicar as quedas da população com DP. O teste de Estabilidade Postural conseguiu diferenciar os indivíduos com DP que sofreram quedas dos que não sofreram quedas, obteve correlações significativas com outros instrumentos que avaliam o equilíbrio e teve boa confiabilidade interexaminador. / Most studies to date have shown that the instruments available for the assessment of fall risk are inadequate for the identification of vulnerable individuals. Therefore, new tests assessing fall risk are strongly needed. This study aimed to translate and validate the Gait and Balance Scale (GABS) for use in patients with Parkinson\'s disease (PD), describe the clinical characteristics of a sample of patients with PD and controls that are related to the fall risk and analyze the Postural Stability test and it validity for assessing fall risk in patients with PD. We selected 107 PD patients at the Movement Disorders Outpatient Clinic of the School of Medicine of Ribeirão Preto - Universidade de São Paulo (USP) and 80 healthy controls. Participants were evaluated using the simplified version of the UPDRS motor scale, HY, SE, FOGQ, FES-I, BBS, and GABS. The Brazilian version of the GABS showed to be valid and reliable, with excellent internal consistency and good test-retest reliability. Furthermore, satisfactory convergent validity with other instruments that assess the same construct was found. In addition to these results, the GABS had good accuracy, sensitivity, specificity, positive predictive value, and negative predictive value. When the GABS was compared with the BBS, the two scales had similar results. However, the GABS showed to be more complete and could analyze more aspects related to fall risk in PD, as postural instability, gait deficits, freezing and fear of falling. Among controls, most falls also occurred indoors, however, they were mostly related to environmental hazards, and not gait. Longer disease duration and greater fear of falling were the factors that most contributed to explain falls in the population with PD. The Postural Stability test is able to differentiate individuals with PD who had experienced falls from those who had not, had significant correlation with others balance instruments and had good interexaminer reliability.

Falls are the leading cause of injuries among Canadians who are aged at 65 years and over. The assessment of dynamic stability has been proved as an effective method to identify fall-prone elderly individuals, which is essential to fall prevention. Tai Chi has been recommended as an effective exercise to prevent falls by the American Geriatric Society and British Geriatric Society. It is important to examine dynamic stability among Tai Chi practitioners and to explore the mechanisms of the effects of Tai Chi practice on fall prevention. This study examined the dynamic postural stability which is assessed by center of mass (COM) range of motion, COM - center of pressure (COP) separation, and temporospacial measures of gait during obstacle-walking in two groups: Tai Chi group and healthy controls. Fifteen participants in each group were asked to complete two walking conditions, level walking and 20cm-obstacle walking. Results showed that when compared with Tai Chi group, control group adopted a conservative crossing strategy with a significantly smaller crossing stride, higher heel clearance, and smaller pre horizontal distance to make obstacle crossing as safe as possible. This conservative strategy indicates the inability to cross obstacle casually and it may be associated with the decline in muscle strength and proprioception. It also showed that Tai Chi practitioners displayed a significantly larger COM range of motion in both anteroposterior (AP) and mediolateral (ML) direction (p<0.05) and a significantly larger COM-COP separation in ML direction (p <0.01), as compared with control group. The larger range of motion of COM and distance between COM and COP indicates that Tai Chi practitioners have a better ability to tolerate unsteadiness, which means if perturbation occurs, Tai Chi practitioners have a larger range to shift COM in the boundary of base of support.

No description available.

Ankle arthritis is a debilitating condition that causes severe pain and decreased function in the affected limb on the order of end-stage hip arthrosis, end-stage kidney disease, and congestive heart failure. Total ankle replacement is a viable surgical option for treating end-stage ankle arthritis, but few have studied its effects on balance over time. Therefore, the purpose of this study was to test the accuracy of a single-marker method of tracking center of mass, evaluate center of pressure measurements in total ankle replacement patients, and analyze lower extremity joint contributions over a two-year recovery period. Subjects stood on two force platforms for ten seconds in different conditions, and relevant variables were calculated from the force platform and 3D motion capture data. Results showed that increasing recovery time restored partial symmetry between the surgical and non-surgical limbs in ground reaction force, ankle range of motion, and ankle and hip moment contribution in static balance tasks. Furthermore, the ankle and hip may have different roles in postural stability. The results of the studies suggest that total ankle replacement is an effective treatment for end-stage ankle arthritis in terms of restoring postural stability. While patients may not have returned to the level of healthy control subjects, they are more functional and more stable after a two-year recovery period. While further work is needed, the results are encouraging for the outlook of ankle arthritis patients who may need total ankle replacement surgery. / Master of Science

Yes / PURPOSE: There is little research evidence to explain why older adults have more problems adapting to new spectacles incorporating astigmatic changes than younger adults. We tested the hypothesis that astigmatic lenses oriented obliquely would lead to errors in verticality perception that are greater for older than younger adults. METHODS: Participants included 12 young (mean ± SD age 25.1 ± 5.0 years) and 12 older (70.2 ± 6.3 years) adults with normal vision. Verticality perception was assessed using a computer-based subjective visual vertical (SVV) task, under static and dynamic (in the presence of a moving peripheral distractor) conditions and when viewing targets through the near refractive correction (control condition), and two forms of astigmatic lenses oriented in the vertical, horizontal, and oblique meridians. RESULTS: The older group demonstrated much greater dynamic SVV errors (e.g., 3.4° for the control condition) than the younger group (1.2°, P = 0.002), larger errors with vertical and horizontal astigmatic lenses (older group 4.1°and 5.2° for toric and magnifier lenses vs. younger group 1.2° and 1.4°, respectively, P < 0.001), and a larger influence of the oblique astigmatic lenses (older group 5.6° vs. younger group 2.1°, P<0.001). CONCLUSIONS: Astigmatic lenses produced little or no errors in SVV in young adults, but large static and dynamic SVV errors in older adults. This indicates a greater reliance on visual input with increased age for SVV, and helps explain why oblique astigmatic refractive corrections can cause dizziness in older patients and why they report greater difficulties adapting to new spectacles with astigmatic changes.

An increase in postural sway is one of the risk factors that have been linked to an increased incidence of falls in the older adult population. Researchers have shown that peripheral sensation is crucial in maintaining a static posture for adults of all ages. It has been reported that older adults have decreased tactile sensation of the plantar surface of their feet. and when the sensory feedback was increased older adults had improved postural control. It was hypothesized that facilitation of the sole of the foot with the use of a semirigid foot orthotic would result in improved postural stability in older adults. Twenty-seven volunteers (19 females, 8 males, mean age: 87 ± 5 yrs) were recruited as subjects from a retirement community. All subjects were supplied with the SmartStep™ Stabilization System. There were a total of 5 Test Days for each subject. The first 2 Test Days were performed while the subjects wore their own shoes, while the last 3 Test Days were performed while the subjects wore the SmartStep™. Test Days 1 and 2 were performed 48 hours apart. Test Day 3 occurred 2 to 4 weeks after Test 2. Test Days 4 and 5 occurred 4-weeks after the prior Test Day. During the 8-weeks between Test Days 3 and 5, subjects were asked to wear the SmartStep™ as their daily shoe. Clinical measures of balance, force plate measurements, sensation testing, and confidence and activity scales were collected on all subjects throughout the eight week test period. Statistical significance was found for 3 of the clinical measures. The Timed “Up & Go” improved from 17.25 to 15.47 sec. The Functional Reach and Lateral Reach Tests demonstrated a decline in scores during the eight weeks. There was only 1 statistically significant finding for the force plate measures. The center of pressure displacement in the anteriorposterior direction was increased from 4.6 to 5.3 cm. No significant differences where reported for any other dependent variable. The results did not indicate statistically that the in-shoe orthotic enhanced postural stability in this group of subjects. However, there were indications that there was a subset of the current population that benefited from the intervention and this needs to be investigated further.