Vestibular compensation.
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BACKGROUND: A poor postural stability in older people is associated with an increased risk of falling. It is recognized that visual environment factors (such as poor lighting and repeating patterns on escalators) may contribute to falls, but little is known about the effects of the visual environment on postural stability in the elderly. OBJECTIVE: To determine whether the postural stability of older women (using body sway as a measure) differed under five different visual environment conditions. METHODS: Subjects were 33 healthy women aged 65-76 years. Body sway was measured using an electronic force platform which identified the location of their centre of gravity every 0.05 s. Maximal lateral sway and anteroposterior sway were determined and the sway velocity calculated over 1-min trial periods. Body sway was measured under each of the following conditions: (1) normal laboratory lighting (186 lx); (2) moderate lighting (10 lx); (3) dim lighting (1 lx); (4) eyes closed, and (5) repeating pattern projected onto a wall. RESULTS: Each measure of the postural stability was significantly poorer in condition 4 (eyes closed) than in all other conditions. Anteroposterior sway was greater in condition 3 than in conditions 1 and 2, whilst the sway velocity was greater in condition 3 than in condition 2. Lateral sway did not differ significantly between different lighting levels (conditions 1-3). A projected repeating pattern (condition 5) did not significantly influence the postural stability relative to condition 1. CONCLUSIONS: The substantially greater body sway with eyes closed than with eyes open confirms the importance of vision in maintaining the postural stability. At the lowest light level, the body sway was significantly increased as compared with the other light levels, but was still substantially smaller than on closing the eyes. A projected repeating pattern did not influence the postural stability. Dim lighting levels and removing visual input appear to be associated with a poorer postural stability in older people and hence might be associated with an increased risk of falls.
BACKGROUND: Depression is one of the most common risk factors for falls, but links between falls and depression are still unclear. Few studies have examined the relationship between depression and gait alteration, which may increase the risk of fall. OBJECTIVE: This study aims to assess a possible relationship between depression, postural and gait abnormalities, and falls. METHODS: We conducted a 1-year prospective study on patients >/=70 years who were admitted to a geriatric unit for 'spontaneous' unexplained falls. Patients were tested for depression using the 30-item Geriatric Depression Scale (GDS). Their motor performances were assessed using the Mini Motor Test (MMT), which is an easy direct-observation test, validated in France, for assessment of frail old people who present with severe postural and gait impairment. This scale is composed of 4 categories of items: (1) abilities in bed; (2) quality of the sitting position; (3) abilities in the standing position, and (4) quality of gait. RESULTS: Sixty-nine patients were included. Depression was found in 46 patients (66.7%). The MMT score was higher in the non-depressed fallers (NDF) group (GDS </=10) compared to the depressed fallers (DF) group (GDS>10; p < 0.05). The 2 groups were compared for each of the 4 items of the MMT: the difference between the DF and NDF groups was mainly explained by the impairment of postural abilities in the standing position. CONCLUSIONS: Our results support the idea that depression is associated with postural abnormalities in the standing position, which may predispose to falls. In clinical practice, more attention should be given to old fallers concerning diagnosis and treatment of associated depression.
BACKGROUND: Vestibular symptoms after surgery diminish rapidly, but the simultaneous progress in active postural control has not been fully addressed. OBJECTIVES: The aim was to evaluate the progress in postural control in operated vestibular schwannoma (VS) patients with visual feedback posturography (VFP). METHODS: 36 consecutive patients with unilateral VS were studied with the VFP pre-operatively, 1 month and 3 months after the surgery. The accuracy and velocity of active postural control movements to distant targets in VFP was measured and compared to that of healthy controls. RESULTS: The hold percentage within the targets was significantly reduced in the VS patients compared to the controls (pre-operatively p = 0.005; postoperatively at 1 month p = 0.002 and at 3 months p = 0.017). The sway velocity (SV) within the targets among patients with VS was significantly increased pre-operatively (p = 0.009), at the 1-month (p = 0.004) and at the 3-month follow-up visits (p = 0.016). All the postural control parameters except SV tended to improve slightly postoperatively. The consecutive VFP measurements in individual VS patients correlated statistically significantly (p < 0.001 for all parameters). The abnormality in the pre-operative VFP results correlated statistically significantly with that of postoperative VFP (p = 0.001). CONCLUSIONS: The VFP is an objective and repeatable method, which can be used to assess and follow up the active postural control in individual patients with VS. Persisting abnormality in the VFP seems to be an indication for more aggressive vestibular rehabilitation to normalize the disturbed postural control.
This report presents observations in 160 patients undergoing chronic spinal cord stimulation for various disorders of the motor system and compares the results obtained using older conventional two-electrode bipolar stimulation with a newly developed four-electrode multiple level system. Improvement was noted in 84% of the 75 patients with cerebral palsy, 67% of the 42 patients with dystonia, 62% of the 21 patients with torticollis and 73% of the 22 patients with post-traumatic neurologic loss. Significant improvements were noted when comparing the two-electrode system with the new multiple level electrode. Marked to moderately improved patients increased from 57 to 84% in cerebral palsy, from 44 to 82% in dystonia, from 53 to 75% in torticollis and from 53 to 80% in dystonia, from 53 to 75% in torticollis and from 53 to 80% in posttraumatic neurologic conditions. There was a corresponding marked drop in unimproved patients in each condition.
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According to the 'equilibrium trajectory' hypothesis, the generation of multi-joint arm movements by the CNS involves the gradual shifting of the hand equilibrium position between the movement end points. This work presents a model which suggests that reaching movements are explicitly planned in terms of spatially and temporally invariant hand equilibrium trajectories. Implementing the model in computer simulations, and using stiffness parameters which were measured during arm posture, arm trajectories were simulated and compared to measured trajectories. The success of the predicted behavior in capturing the fine kinematic details of measured movements supports the validity of the proposed model for biological trajectory control.
Detailed neurological examinations and body sway measurements with a stable force measuring platform were carried out on 30 healthy adults between 21 and 63 years of age. The results were analyzed for sex- and age-associated changes with regard to three different sway components (total sway, anterio-posterior sway, lateral sway) and two different conditions (eyes open, eyes closed). Sex-associated differences were highly significant for all sway components in the oldest age group (51-65 years) in which men exhibited more spontaneous postural sway than women in the condition eyes open. With eyes closed these differences increased. Middle-aged men (36-50 years) also exhibited significantly more postural sway than women of the same age. In the condition eyes open especially total sway and anterioposterior sway were increased, whereas in the condition eyes closed total sway and lateral sway were predominantly higher in men than in women. In the youngest age group (21-35 years) no sex-related differences in postural sway were found. Age-associated differences were significant for anterioposterior sway (eyes open) in men, increasing continuously from the young to the middle-aged, and again from the middle-aged to the older age group. Anterioposterior sway in women, on the contrary, did not change with age. Age-associated differences in women were found for total sway (eyes open) and lateral sway (eyes closed). However, the highest values for total sway and lateral sway within the female group were obtained from young women in both conditions eyes open and eyes closed.(ABSTRACT TRUNCATED AT 250 WORDS)
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Eighty-one elderly residents of a hostel for the aged (mean age 83.3 years) underwent clinical medical assessments to examine susceptibility to falling. The medical examination was structured and followed a clinical format with particular emphasis upon posture and gait, in addition to routine examination of the cardiovascular, respiratory, neurological, gastrointestinal, haemopoietic, genitourinary, musculoskeletal and visual systems. These subjects were then followed up for 1 year to assess whether these clinical measures were associated with falls. Seventy-six residents were available for follow-up. Thirty-four subjects (44.7%) reported having no falls in the follow-up year, 10 (13.2%) fell once only, 13 (17.1%) fell on two occasions whilst 19 (25.0%) fell three or more times. Seventy-two percent of all falls occurred in the hostel building. Certain clinical factors showed high specificity (i.e. only a few non-fallers screened positive in the tests) but low sensitivity (i.e. there were considerable numbers of residents who screened negatively, but fell in the 12-month follow-up period). Stepwise logistic regression analysis revealed impaired cognition, abnormal reaction to any push or pressure, history of palpitations and abnormal stepping as variables that independently and significantly predicted falling. The equation predicted falls with 70.7% sensitivity and 79.4% specificity, with an overall predictive accuracy of 74.7%. It appears that a modified focussed clinical examination could provide the basis of a short assessment for predicting falls and highlight possible intervention strategies for reducing fall risk.
A 1-year prospective study was conducted in an intermediate care institution to determine whether a combined assessment of physiological and clinical measures discriminates between elderly fallers and elderly nonfallers. Seventy persons aged between 72 and 96 years (mean 85.6), who were generally independent in activities of daily living, took part in the study, and 66 were available to follow-up. In the follow-up year, 24 subjects experienced no falls, 20 subjects fell one time only and 22 residents fell on two or more occasions. Discriminant analysis identified reaction time, body sway, quadriceps strength, tactile sensitivity, gait impairment, cognitive impairment, psychoactive drug use and age as the variables that significantly discriminated between subjects who experienced falls and those who did not. This procedure correctly classified 86% of subjects into faller and nonfaller groups. These findings suggest that an assessment that combines physiological and clinical factors provides excellent discrimination between elderly fallers and nonfallers.
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The frequency spectrum of the center of gravity in normal subjects while standing was recorded by using a platform-strain gauge system and a digital computer. Individual differences of the spectral patterns resulted in the classification of three types. Averaged divisional frequency of each type was calculated in the range below 1 Hz in which the main change between the values with eyes open and those with eyes closed appeared as the frequency shift.
We carried out a questionnaire survey regarding the symptoms of orthostatic dysregulation (OD) and administered the Schellong test to 301 healthy young females ranging in age from 18 to 21 years. OD was identified in 62 (20.6%) of the subjects based on the questionnaire. Although orthostatic dizziness was relatively common in the entire group of young females (171/301, 56.8%), this symptom was much more prevalent in the subjects with OD (58/62, 93.5%). There was also a highly significant difference between the systolic pressure decrease during the Schellong test procedure in 22 subjects with OD with frequent orthostatic dizziness and that in the 239 subjects without OD. Although the clinical value of the Schellong test in the assessment of OD and other related conditions has been brought into question because of its relatively poor specificity, we conclude that this test procedure may be useful in screening for OD or autonomic nerve dysfunction, since it presents the advantage of easy application in clinical practice.
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