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At least 757 records · Page 42Linked to original sources

PubMed1995

Inter-rater reliability of a clinical test of standing function.

The Functional Standing Test (FST) has been proposed and described as an evaluative tool to assess a person's ability to perform one-handed reaching tasks while standing. The test items, several of which are identical to those in the Jebson Test of Hand Function, require the manipulation of objects on a counter top and on simulated kitchen shelves while the person is standing. The purpose of this study was to assess the inter-rater reliability of FST when it is administered to adolescents with spinal cord injuries who stand with braces, and to able-bodied young adults. Two testers administered the FST separately to three individuals with spinal cord injuries (SCI) below T-2 who stood with knee-ankle-foot orthoses (KAFOs) and to 10 able-bodied people who stood unassisted. The order in which the testers operated was randomized and the Intraclass Correlation Coefficient (ICC (2,1)) was used to analyze inter-rater reliability. Eighty percent of the subtests were found to be moderately to very reliable when applied to either group on the same day. Half of the test items were categorized as having the same level of inter-rater reliability between the two sample populations. A modified version of the test eliminating unreliable components could serve as a valuable and inexpensive means of evaluating the effectiveness of various therapies and technologies to provide or assist standing function. Validity and specificity of the test remain the focus of future research.

Adolescent↗

PubMed2006

Effects of diabetic neuropathy on body sway and slip perturbation detection in older population.

Postural control is a common mechanism to compensate for unexpected displacements of the body. In the older population, a slip or fall due to a failure of postural control is a common cause of morbidity and mortality. The ability of postural control decreases with aging or neuropathy. In this study, 2 groups, diabetics and non-diabetics in the older population, were compared to determine how patterns of postural sway during quiet standing were related to the detection of perturbation. The SLIP-FALLS system was applied to the measurement of sway and detection of perturbation. In phase 1 of the development of the predictive model, neural network algorithms were applied to find determinant variables for perturbation detection. In phase 2, a fuzzy logic inference system was developed to investigate the relationship between sway and perturbation detection. Results of this study may be applied to the design of floor mats or shoe insoles for preventing fatigue in workplaces.

Aging↗

PubMed2005

Contraversive pushing and inattention of the contralesional hemispace.

The aim of this study was to investigate, in 114 stroke patients, the frequency of occurrence of a largely unknown neurological disorder, characterized by a postural imbalance due to a 'pushing away' reaction of the body towards the contralesional side of space, in function of hemispheric lesion localization and gender. The study also investigate the relation of this contraversive pushing with active movement, somatosensory perception deficits and, in particular, inattention of contralesional hemispace and body. The similarity of the presence of contraversive pushing and the syndrome of spatial hemineglect together with a gender-related differentiation suggest the existence of a "pusher syndrome", in which the pathophysiology points in the direction of a spatial higher-order processing deficit, related to spatial inattention, underlying the higher frequency and severity of contraversive pushing after right brain lesions.

Aged↗

PubMed2001

Effects of daily dermal application of DEET and epermethrin, alone and in combination, on sensorimotor performance, blood-brain barrier, and blood-testis barrier in rats.

DEET and permethrin were implicated in the development of illnesses in some veterans of the Persian Gulf War. This study was designed to investigate the effects of daily dermal application of these chemicals, alone or in combination, on the permeability of the blood-brain barrier (BBB) and blood-testes barrier (BTB) and on sensorimotor performance in male Sprague-Dawley rats. Groups of five rats were treated with a dermal daily dose of 4, 40, or 400 mg/kg DEET in ethanol or 0.013, 0.13, or 1.3 mg/kg permethrin in ethanol for 60 d. A group of 10 rats received a daily dermal dose of ethanol and served as controls. BBB permeability was assessed by injection of an iv dose of the quaternary ammonium compound [3H]hexamethonium iodide. While permethrin produced no effect on BBB permeability, DEET alone caused a decrease in BBB permeability in brainstem. A combination of DEET and permethrin significantly decreased the BBB permeability in the cortex. BTB permeability was decreased by treatment with DEET alone and in combination with permethrin. The same animals underwent a battery of functional behavior tests 30, 45, and 60 d after exposure to evaluate their sensorimotor abilities. All treatments caused a significant decline in sensorimotor performance in a dose- and time-dependent manner. These results show that daily dermal exposure to DEET, alone or in combination with permethrin, decreased BBB permeability in certain brain regions, and impaired sensorimotor performance.

Administration, Topical↗

PubMedDate not supplied

Postural stability is compromised by fatiguing overhead work.

In a laboratory setting, 16 participants performed a repetitive overhead tapping task for 3 hours or until self-terminated due to substantial shoulder discomfort. Several measures of postural sway and stability were obtained using a force plate, both during quiet standing and during performance of the tapping task. Sway area and peak sway velocity showed consistent increases with time, whereas changes in average velocity and peak whole-body center-of-mass acceleration were either small or nonsignificant. Although relatively insensitive to several task variables, changes in sway areas and peak velocities were substantially larger in trials terminated by the participants. It is argued that fatigue plays a more important role than simple task duration in causing the observed increases in sway, and hence decreases in postural stability. Potential whole-body consequences of localized musculoskeletal stresses appear supported by the results, and implications for safety, risks of falls, and work scheduling are discussed.

Accidental Falls↗

PubMed2002

Reorganization of equilibrium and movement control strategies after total knee arthroplasty.

This work was aimed at identifying changes in posturomotor control strategies in patients with unilateral total knee arthroplasty. Using kinetic and kinematic data, a previous study had revealed that, during a side step, patients with unilateral knee arthritis showed a shortened monopodal phase and a lengthened postural phase when the affected leg was the supporting one. It was expected that these strategies would be modified after undergoing total knee arthroplasty. Postoperatively the durations of the monopodal phase and of the postural phase became similar when the operated limb was supporting and when the sound limb was supporting. Concerning the upper body movements, the same asymmetrical results as before surgery were observed. Hence, patients with total knee arthroplasty exhibit posturomotor strategies which, although they become close to normal, remain asymmetrical. The durations of the monopodal and of the postural phases could be considered to assess the results of total knee arthroplasty.

Aged↗

PubMed2003

Dizziness and unsteadiness following whiplash injury: characteristic features and relationship with cervical joint position error.

Dizziness and/or unsteadiness are common symptoms of chronic whiplash-associated disorders. This study aimed to report the characteristics of these symptoms and determine whether there was any relationship to cervical joint position error. Joint position error, the accuracy to return to the natural head posture following extension and rotation, was measured in 102 subjects with persistent whiplash-associated disorder and 44 control subjects. Whiplash subjects completed a neck pain index and answered questions about the characteristics of dizziness. The results indicated that subjects with whiplash-associated disorders had significantly greater joint position errors than control subjects. Within the whiplash group, those with dizziness had greater joint position errors than those without dizziness following rotation (rotation (R) 4.5 degrees (0.3) vs 2.9 degrees (0.4); rotation (L) 3.9 degrees (0.3) vs 2.8 degrees (0.4) respectively) and a higher neck pain index (55.3% (1.4) vs 43.1% (1.8)). Characteristics of the dizziness were consistent for those reported for a cervical cause but no characteristics could predict the magnitude of joint position error. Cervical mechanoreceptor dysfunction is a likely cause of dizziness in whiplash-associated disorder.

Adolescent↗

PubMed1996

Calculation of area of stabilometric signals using principal component analysis.

In stabilometry, the sway of the human body in an upright posture is studied by monitoring the displacement of its centre of pressure in the lateral (x) and anterio-posterior (y) directions. The area covered by this trace has been defined as that of an ellipse fitted to the data. Conventionally, its angle of inclination is found through linear regression (LR) on the data in the x-y plane. In the present paper, principal component analysis (PCA) is proposed as providing a more suitable basis for the estimation of angle and area. Results of simulations and stabilometric tests confirm large differences between area and angle estimates obtained by regression of x over y, and y over x, with PCA generally agreeing with either one or the other of the LRs. The PCA technique is therefore recommended as an improved basis for measuring area and inclination of stabilograms, or similar data sets.

Data Interpretation, Statistical↗

PubMed1998

Repeatability of body sway measurements; day-to-day variation measured by sway magnetometry.

The postural stability of 30 normal subjects in the age range 15 to 64 years was measured on five separate occasions, using the sway magnetometry technique, to determine the day-to-day repeatability of this measurement technique. On each occasion the pathlength and area enclosed by movement of the hips in a horizontal plane were measured over two 30 s periods with eyes open and eyes closed, with subjects standing on a firm base. Day-to-day repeatability had a standard deviation of 14% for pathlength and 42% for area. Neither the age nor the sex of the subject had any demonstrable effect on the results.

Adolescent↗

PubMed1982

Clinical correlates of sway in old age--sensory modalities.

Sway has been measured by Wright's Ataxiameter in 151 frail elderly and five young subjects, and compared with various sensory modalities. There is a close relationship between increased sway and impaired vibration sense in the legs. No correlations emerged with proprioception but this may reflect the imprecision of the test. That neither vision nor vestibular deprivation correlated with sway confirms the place of these senses as secondary in the maintenance of posture. Vestibular impairment was found in only 6% of the elderly subjects, by tilt test--and these were the very old. There was a limited relationship between falls in the past year and both sway and proprioception.

Accidents↗

PubMed1982

The relationship of postural sway in standing to the incidence of falls in geriatric subjects.

A double-blind study was undertaken to determine the relationship (if one exits) between the extent of postural sway in standing of individual elderly subjects and their frequency of falling. A total of 205 subjects were studied; their average age was 81.8 years. Thirty per cent of the men, and 46% of the women, had one or more falls; the proportion of all subjects with one or more falls was 42%. The average speed of sway was significantly greater (P less than 0.05) for those who fell one or more times in a year than for those who did not fall. In this group of institutionalized elderly, there was no sex-related difference in the mean speed of sway; moreover, no age-related trend was demonstrated by the regression of mean speed upon age for all subjects. The mean speed of sway even for the non-fallers was found to be greater than that measured in a sample of non-institutional elderly subjects studied in the past. Thus, mean speed of postural sway was found to be only of statistical value for determining the risk of falling among these institutionalized elderly. We found postural sway to be an indicator of a tendency to fall, but the difference was less than might have been expected. No trend of increasing postural sway correlating with the increased frequency of falls was found.

Accidents↗

PubMed1990

Postural control in elderly subjects.

The postural stability of 23 subjects aged 85 years or over was studied with a force platform. The sensory function of the lower limbs was disturbed with small vibrators placed on both calf muscles and/or by placing the subjects on a platform covered with foam plastic. When compared with a group (n = 100) of 50-60-year-old subjects, the elderly subjects had significantly higher sway velocities even during nonperturbed conditions. The perturbation of muscle spindles with vibration and/or pressoreceptor function with foam plastic did not increase the postural instability of the elderly subjects. Visual deprivation had a significant effect on postural stability, and the visual influx contributed about 50% of the postural stability. Postural control is reduced as a result of loss of sensory cues of pressoreceptors and also deterioration in function of stretch reflexes initiated from muscle spindles. The very elderly seem to rely on visual control of posture; this is slow, which can be one reason for susceptibility to falls.

Age Factors↗

PubMed1991

Visual acuity and contrast sensitivity in relation to falls in an elderly population.

Visual acuity and contrast sensitivity were measured in 95 residents of a hostel for the aged (mean age = 83 years) using a dual-contrast letter chart and the Melbourne Edge Test (MET). Vision (as measured by visual acuity, the MET, low-contrast visual acuity, and difference between high- and low-contrast acuity) decreased significantly with age and all four measures were significantly correlated. Subjects with a clinical eye disorder had poorer vision than those without a disorder although the differences were not significant. Visual acuity and contrast sensitivity were not associated with body sway when subjects were standing on a firm base. However, when the subjects were placed in a situation which provided reduced support (standing on a compliant surface), body sway was associated with poor visual acuity and contrast sensitivity. There was also a difference in contrast sensitivity between those who fell one or more times in a year of follow-up and those who did not fall. It appears that reduced vision may be a predisposing factor to postural imbalance and falls in elderly persons.

Accidental Falls↗

PubMed1995

Association of age with the threshold for detecting ankle inversion and eversion in upright stance.

A randomized quadruple staircase method and probit analysis were used to measure the thresholds for sensation of ankle inversion and eversion by 18 healthy young and 18 healthy old subjects while standing with a foot in a servo-driven cradle. The results of over 3600 trials show that the mean threshold for detecting inversion with a probability of 75% was 0.35 degrees in the older subjects, a value significantly greater than the 0.06 degrees threshold found in the younger group. The corresponding thresholds in eversion were significantly greater in both old (0.52 degrees) and young (0.35 degrees) subjects. Significant, but smaller, age differences were also found in unipedal stance. Few significant sex differences were found. When the velocity of a 0.1 degree inversion movement was increased from 2 to 200 degrees/s the probability of detecting it rose by only 22.6%. Although significantly increased with age, the threshold for sensing rotation in the weight-bearing ankle was measured in tenths of degrees, an order of magnitude better than previously reported (non-weight-bearing) values.

Adult↗

PubMed1995

Mobility after proximal femoral fracture: the relevance of leg extensor power, postural sway and other factors.

We studied 40 previously healthy women (median age 83 years 90% central range 77-90) 1 week after surgical fixation of their proximal femoral fracture to establish the significance of leg extensor power, postural sway, age, pre-injury mobility and fracture type in recovery of walking and stair-climbing ability. Subjects demonstrated a range of walking and stair-climbing abilities. Those not mobile all had sway greater than 40.9 cm/1 min and were more likely to have suffered a trochanteric fracture (p < 0.05). These subjects were not the oldest or those with the worst pre-injury mobility, but did report much greater pain (p < 0.05). Multiple linear regression revealed leg extensor power in the fractured leg (LEPf) to be the most important determinant of walking speed (R2 0.40, p < 0.001) and stair climbing time (R2 0.33, p < 0.002). LEPf was less than in the uninjured leg (p < 0.001), and accounted for only 30% of the total power output. LEPf was determined by pain, and not pre-injury mobility or fracture pattern. These findings have implications for the development of rehabilitation programmes.

Activities of Daily Living↗

PubMed2006

Obstacle clearance and prevention from falling in the bipedally walking Japanese monkey, Macaca fuscata.

BACKGROUND: studies are needed which consider CNS-controlled strategies for accommodating perturbed bipedal (Bp) posture and walking. OBJECTIVE: to demonstrate the suitability of the Japanese monkey, Macaca fuscata, for the above purpose. SETTING AND SUBJECTS: three adult monkeys were operantly trained to use Bp-walking on a moving treadmill belt. On one side of the belt, a rectangular adjustable-height obstacle confronted the ipsilateral leg every 4-6 steps, as determined by belt speed. METHODS: animal posture and walking patterns were captured and digitized by two high-speed video systems. Frame-by-frame analyses of side- and back-view kinematics were obtained. RESULTS: the monkeys learned quickly to proactively clear the in-coming obstacles by use of a flexible hip-knee-ankle flexion strategy. This featured an appropriate postural adjustment and leg trajectory. In cases where a monkey failed to clear the obstacle, it promptly adopted a defensive posture to avoid falling. There was then a quick return to a posture that allowed the resumption of a Bp gait. CONCLUSIONS: when Bp posture and gait are perturbed in a non-human primate model, the prompt adjustment of a flexible hip-knee-ankle flexion strategy and a defensive postural adjustment act together to prevent a fall and enable the speedy resumption of normal Bp posture and gait.

Accidental Falls↗

PubMed2006

Visual risk factors for falls in older people.

Poor vision reduces postural stability and significantly increases the risk of falls and fractures in older people. Most studies have found that poor visual acuity increases the risk of falls. However, studies that have included multiple visual measures have found that reduced contrast sensitivity and depth perception are the most important visual risk factors for falls. Multifocal glasses may add to this risk because their near-vision lenses impair distance contrast sensitivity and depth perception in the lower visual field. This reduces the ability of an older person to detect environmental hazards. There is now evidence that maximising vision through cataract surgery is an effective strategy for preventing falls. Further randomised controlled trials are required to determine whether individual strategies (such as restriction of use of multifocal glasses) or multi-strategy visual improvement interventions can significantly reduce falls in older people. Public health initiatives are required to raise awareness in older people and their carers of the importance of regular eye examinations and use of appropriate prescription glasses.

Accidental Falls↗

PubMed1987

Pathological eye-head coordination in roll: tonic ocular tilt reaction in mesencephalic and medullary lesions.

The fundamental pattern of coordinated eye-head roll motion is based upon utricular/saccular as well as vertical canal input, and mediated by the graviceptive pathways from the labyrinths via pontomedullary vestibular nuclei to the rostral midbrain tegmentum. The tonic bilateral graviceptive input stabilizes the eyes and head in the normal upright position. A unilateral lesion causes imbalance in vestibular tone in the roll plane which results in a tonic ipsiversive ocular tilt reaction (OTR). OTR, the triad of ipsilateral head tilt, skew deviation and ocular torsion, occurred as a tonic response (nonparoxysmal) persisting over months to years and was presumed to be due to upper brainstem lesions in 3 patients. Precise localization was limited because of the nature of the lesions. A reversible tonic OTR was seen with acute infarction of the dorsolateral medulla oblongata in 4 out of 11 patients. It may be explained by an ipsilateral lesion of the posterior canal pathways. Transient OTR seems not to be rare in acute Wallenberg's syndrome and ocular torsion in these patients is dysconjugate with predominant excyclotropia of the ipsilateral hypotropic eye. A deviation of the subjective visual vertical in the direction of the spontaneous head tilt--a previously undescribed feature of OTR--was present in all 7 patients and indicates a pathological shift of the internal representation of the gravitational vector. With respect to perception (subjective vertical) it is proposed that the manifest ipsiversive OTR represents a motor compensation of an apparent eye-head tilt contraversive to the lesioned side. Despite the resulting postural imbalance and the conflicting true vertical of the visual surround, the eyes, head and body are continuously adjusted to what the central nervous system erroneously computes as being vertical.

Adult↗