A prospective study of posturography in normal older people

Effects of aging on otolith morphology and functions in mice

Background

Increased fall risk caused by vestibular system impairment is a significant problem associated with aging. A vestibule is composed of linear acceleration-sensing otoliths and rotation-sensing semicircular canals. Otoliths, composed of utricle and saccule, detect linear accelerations. Otolithic organs partially play a role in falls due to aging. Aging possibly changes the morphology and functions of otoliths. However, the specific associations between aging and otolith changes remain unknown. Therefore, this study aimed to clarify these associations in mice.

Methods

Young C56BL/6 N (8 week old) and old (108-117 weeks old) mice were used in a micro-computed tomography (μCT) experiment for morphological analysis and a linear acceleration experiment for functional analysis. Young C56BL/6 N (8 week old) and middle-aged (50 week old) mice were used in electron microscopy experiments for morphological analysis.

Results

μCT revealed no significant differences in the otolith volume (p = 0.11) but significant differences in the otolith density (p = 0.001) between young and old mice. μCT and electron microscopy revealed significant differences in the structure of striola at the center of the otolith (μCT; p = 0.029, electron microscopy; p = 0.017). Significant differences were also observed in the amplitude of the eye movement during the vestibulo-ocular reflex induced by linear acceleration (maximum amplitude of stimulation = 1.3G [p = 0.014]; maximum amplitude of stimulation = 0.7G [p = 0.015]), indicating that the otolith function was worse in old mice than in young mice.

Discussion

This study demonstrated the decline in otolith function with age caused by age-related morphological changes. Specifically, when otolith density decreased, inertial force acting on the hair cells decreased, and when the structure of striola collapsed, the function of cross-striolar inhibition decreased, thereby causing a decline in the overall otolith function.

Patient-stimulated fall prevention screening in primary care: analysis of provider coding changes

BACKGROUND

The Centers for Disease Control and Prevention (CDC) has developed an evidenced based clinical screening tool, Stopping Elderly Accidents, Deaths & Injuries (STEADI) but penetration into routine clinical practice has been slow. To increase screening for falls and fall risk in an internal medicine primary care practice, a patient-centered screening program was integrated into a busy academic clinic.

METHODS

Over a three month period, Patients were invited to self-screen via a large poster in the waiting room, and complete a STEADI Staying Independent questionnaire, and discuss findings with their healthcare provider. Fall Prevention Booklets were made readily available in clinic exam rooms. Questionnaires and fall prevention booklets, were uniquely numbered, and Epic Slicer-Dicer reports were utilized to evaluate falls screening-related ICD-10 codes determined a priori. Generalized linear modeling calculated difference-in-difference compared with other clinics without this program for rates of coding for fall-related diagnosis codes.

RESULTS

In three months, 255 questionnaires were taken; only 5 (2%) were returned for later review. 110 booklets were disseminated from clinic exam rooms. The absolute difference-in-difference in ICD-10 coding was 0.7% compared to other clinics in the same practice, and year before. Generalized linear modeling showed a 4.7% increased impact in screening-related ICD-10 codes, which was statistically significant (P =  < .0001) without reported disruption to clinical workflows.

CONCLUSION

There are indicators that patient-centered selective screening at a busy academic practice may have resulted in an increase in falls-related ICD-10 coding. Clinical integration of this program was well received.

Systematic review of candidate prognostic factors for falling in older adults identified from motion analysis of challenging walking tasks

The objective of this systematic review is to identify motion analysis parameters measured during challenging walking tasks which can predict fall risk in the older population. Numerous studies have attempted to predict fall risk from the motion analysis of standing balance or steady walking. However, most falls do not occur during steady gait but occur due to challenging centre of mass displacements or environmental hazards resulting in slipping, tripping or falls on stairs. We conducted a systematic review of motion analysis parameters during stair climbing, perturbed walking and obstacle crossing, predictive of fall risk in healthy older adults. We searched the databases of Pubmed, Scopus and IEEEexplore.A total of 78 articles were included, of which 62 simply compared a group of younger to a group of older adults. Importantly, the differences found between younger and older adults did not match those found between older adults at higher and lower risk of falls. Two prospective and six retrospective fall history studies were included. The other eight studies compared two groups of older adults with higher or lower risk based on mental or physical performance, functional decline, unsteadiness complaints or task performance. A wide range of parameters were reported, including outcomes related to success, timing, foot and step, centre of mass, force plates, dynamic stability, joints and segments. Due to the large variety in parameter assessment methods, a meta-analysis was not possible. Despite the range of parameters assessed, only a few candidate prognostic factors could be identified: older adults with a retrospective fall history demonstrated a significant larger step length variability, larger step time variability, and prolonged anticipatory postural adjustments in obstacle crossing compared to older adults without a fall history. Older adults who fell during a tripping perturbation had a larger angular momentum than those who did not fall. Lastly, in an obstacle course, reduced gait flexibility (i.e., change in stepping pattern relative to unobstructed walking) was a prognostic factor for falling in daily life. We provided recommendations for future fall risk assessment in terms of study design.In conclusion, studies comparing older to younger adults cannot be used to explore relationships between fall risk and motion analysis parameters. Even when comparing two older adult populations, it is necessary to measure fall history to identify fall risk prognostic factors.

Severity-dependent variations of the neutrophil to lymphocyte ratio (NLR) in peripheral vestibular vertigo

Background

Peripheral vestibular vertigo is a common cause of vertigo especially in the elderly. The neutrophil to lymphocyte ratio (NLR) is a rapid and cost-effective inflammatory marker that has been assessed previously in peripheral vestibular disorders. However, its relation to the severity of peripheral vertigo has not been previously investigated. The aim of this study is to assess the levels of NLR in peripheral vestibular vertigo of various severity categories. This was a cross-sectional study at the Wahidin Sudirohusodo Hospital and Hasanuddin University Teaching Hospital in Makassar. The NLR was measured among subjects with periphel vestibular vertigo with severity categorised using the Dizziness Handicap Inventory (DHI) questionnaire.

Results

A total of 39 participants with peripheral vestibular vertigo were recruited. A statistically significant difference was found (p = 0.002, Kruskal–Wallis ANOVA) between the mean NLR for the mild, moderate, and severe DHI categories were 2.47 ± 1.66, 2.64 ± 0.96, and 5.15 ± 2.59 respectively.

Conclusion

A significant difference in the NLR was found between the three different vertigo severity groups, wherein NLR values rise with increase in vertigo severity. This warrants further exploration on the role of inflammatory biomarkers in vertigo pathophysiology and clinical assessment.

Are Static and Dynamic Postural Balance Assessments Two Sides of the Same Coin? A Cross-Sectional Study in the Older Adults

The aim of this study was to investigate if the combination of static and dynamic postural balance assessments gives more accurate indications on balance performance among healthy older adults. We also aimed at studying the effect of a dual-task condition on static and dynamic postural balance control. Fifty-seven healthy older adults (age = 73.2 ± 5.0 year, height = 1.66 ± 0.08 m, and body mass = 72.8 ± 13.8 kg) completed the study. Static and dynamic balance were assessed both in single-task and dual-task conditions through a force plate and an oscillating platform. The dominant handgrip strength was also measured with a dynamometer. Pearson’s correlation revealed non-statistically significant correlations between static and dynamic balance performance. The dual-task worsened the balance performance more in the dynamic (+147.8%) than in the static (+25.10%, +43.45%, and +72.93% for ellipse area, sway path, and AP oscillations, respectively) condition (p < 0.001). A weak correlation was found between dynamic balance performance and handgrip strength both in the single (p < 0.05; r = −0.264) and dual (p < 0.05; r = −0.302) task condition. The absence of correlations between static and dynamic balance performance suggests including both static and dynamic balance tests in the assessment of postural balance alterations among older adults. Since cognitive-interference tasks exacerbated the degradation of the postural control performance, dual-task condition should also be considered in the postural balance assessment.

Discrimination of standing postures between young and elderly people based on center of pressure

Posturography is utilized to assess the influence of aging on postural control. Although this measurement is advantageous for finding group-level differences between the young and the elderly, it is unclear whether it has the potential to differentiate elderly individuals who are affected by various impacts of aging. The purpose of this study was to determine the utility of posturography to discriminate elderly individuals from young adults. We investigated the performances of the random forest classifiers constructed from center of pressure (COP) indices for discriminating standing postures between healthy elderly and young people. Postural sways in 19 young and 31 community-dwelling elderly participants were measured using force plates in 4 standing conditions: bipedal standing, standing on a narrow base, standing on foam rubber, and standing with eyes closed. We further verified the informative predictors that contributed to the prediction model. As the results, the classifier based on the COP indices for standing on foam rubber showed the best performance (accuracy: 93.4%, sensitivity: 94.4%, specificity: 93.6%, area under the curve of receiving operator characteristics: 0.95), followed by the classifier for standing with eyes closed. The informative predictors varied depending on the postural conditions. Our findings demonstrated the potential of posturography for identifying elderly postures. The evaluation of sensory re-weighting using the appropriate COP indices would be a useful clinical tool for detecting the progress of aging on postural control.

Center of pressure displacement characteristics differentiate fall risk in older people: A systematic review with meta-analysis

Falling is the second most prevalent cause of accidental death in the world. Currently available clinical tests to assess balance in older people are insufficiently sensitive to screen for fall risk in this population. Laboratory tests that record the center of pressure (COP) trajectory could overcome this problem but despite their widespread use, the choice of COP trajectory features for use as a biomarker of fall risk lacks consensus. This systematic review and meta-analysis aimed at identifying the best COP characteristics to predict risk of falling in older adults. More than 4000 articles were screened; 44 (7176 older adults) were included in this study. Several COP parameters emerged as good indices to discriminate fallers from non-fallers. From sensitivity analysis, Sway area per unit time, anteroposterior mean velocity, and radial mean velocity were the best traditional features. In this study, identification of older people with a high fall risk was demonstrated using quiet-standing recordings. Such screening would also be useful for routine follow-up of balance changes in older fallers in clinical practice.

Sensory-Challenge Balance Exercises Improve Multisensory Reweighting in Fall-Prone Older Adults

BACKGROUND AND PURPOSE

Multisensory reweighting (MSR) deficits in older adults contribute to fall risk. Sensory-challenge balance exercises may have value for addressing the MSR deficits in fall-prone older adults. The purpose of this study was to examine the effect of sensory-challenge balance exercises on MSR and clinical balance measures in fall-prone older adults.

METHODS

We used a quasi-experimental, repeated-measures, within-subjects design. Older adults with a history of falls underwent an 8-week baseline (control) period. This was followed by an 8-week intervention period that included 16 sensory-challenge balance exercise sessions performed with computerized balance training equipment. Measurements, taken twice before and once after intervention, included laboratory measures of MSR (center of mass gain and phase, position, and velocity variability) and clinical tests (Activities-specific Balance Confidence Scale, Berg Balance Scale, Sensory Organization Test, Limits of Stability test, and lower extremity strength and range of motion).

RESULTS

Twenty adults 70 years of age and older with a history of falls completed all 16 sessions. Significant improvements were observed in laboratory-based MSR measures of touch gain (P = 0.006) and phase (P = 0.05), Berg Balance Scale (P = 0.002), Sensory Organization Test (P = 0.002), Limits of Stability Test (P = 0.001), and lower extremity strength scores (P = 0.005). Mean values of vision gain increased more than those for touch gain, but did not reach significance.

DISCUSSION AND CONCLUSIONS

A balance exercise program specifically targeting multisensory integration mechanisms improved MSR, balance, and lower extremity strength in this mechanistic study. These valuable findings provide the scientific rationale for sensory-challenge balance exercise to improve perception of body position and motion in space and potential reduction in fall risk.

Postural adjustments in anticipation of predictable perturbations allow elderly fallers to achieve a balance recovery performance equivalent to elderly non-fallers

BACKGROUND

In numerous laboratory-based perturbation experiments, differences in the balance recovery performance of elderly fallers and non-fallers are moderate or absent. This performance may be affected by the subjects adjusting their initial posture in anticipation of the perturbation.

RESEARCH QUESTIONS

Do elderly fallers and non-fallers adjust their posture in anticipation of externally-imposed perturbations in a laboratory setting? How does this impact their balance recovery performance?

METHODS

21 elderly non-fallers, 18 age-matched elderly fallers and 11 young adults performed both a forward waist-pull perturbation task and a Choice Stepping Reaction Time (CSRT) task. Whole-body kinematics and ground reaction forces were recorded. For each group, we evaluated the balance recovery performance in the perturbation task, change in initial center of mass (CoM) position between the CSRT and the perturbation task, and the influence of initial CoM position on task performance.

RESULTS

The balance recovery performance of elderly fallers was equivalent to elderly non-fallers (p > 0.5 Kolmogorov-Smirnov test). All subject groups anticipated forward perturbations by shifting their CoM backward compared to the CSRT task (young: 2.1% of lower limb length, elderly non-fallers: 2.7%, elderly fallers: 2.2%, Hodges-Lehmann estimator, p < 0.001 Mann-Whitney U). This backward shift increases the probability of resisting the traction without taking a step.

SIGNIFICANCE

The ability to anticipate perturbations is preserved in elderly fallers and may explain their preserved balance recovery performance in laboratory-based perturbation tasks. Therefore, future fall risk prediction studies should carefully control for this postural strategy, by interleaving perturbations of different directions for example.

Evaluating the Effects of Kinesthetic Biofeedback Delivered Using Reaction Wheels on Standing Balance

Aging, injury, or ailments can contribute to impaired balance control and increase the risk of falling. Provision of light touch augments the sense of balance and can thus reduce the amount of body sway. In this study, a wearable reaction wheel-based system is used to deliver light touch-based balance biofeedback on the subject's back. The system can sense torso tilt and, using reaction wheels, generates light touch. A group of 7 healthy young individuals performed balance tasks under 12 trial combinations based on two conditions each of standing stance and surface types and three of biofeedback device status. Torso tilt data, collected from a waist-mounted smartphone during all the trials, were analyzed to determine the efficacy of the system. Provision of biofeedback by the device significantly reduced RMS of mediolateral (ML) trunk tilt (p < 0.05) and ML trunk acceleration (p < 0.05). Repeated measures ANOVA revealed significant interaction between stance and surface on reduction in RMS of ML trunk tilt, AP trunk tilt, ML trunk acceleration, and AP trunk acceleration. The device shows promise for further applications such as virtual reality interaction and gait rehabilitation.

Age related changes in balance performance during self-selected and narrow stance testing

BACKGROUND

Various balance tests have been considered as fall risk screening tools however there is a lot of variability in the methods and outcome measures reported. Based on previous research examining age-related changes in balance and differences between fallers and nonfallers, the purpose of this investigation was to examine age-related balance changes, as reflected in medial-lateral center of pressure (CP) velocity, in community-dwelling/independently living adults (≥60years) during self-selected and narrow stance testing with eyes opened and closed.

METHODS

Two hundred and thirty adults aged 60yrs or older completed one 45s trial under two stances (self-selected, narrow) and two visual conditions (eyes opened, eyes closed). Average medial-lateral CP velocity was computed from the CP data, with preliminary analysis demonstrating positive skewness and association with body height. A sway velocity index (SVI) was created by a natural logarithm transformation and dividing by body height. Multiple linear regression was used to determine the association between age, visual condition, stance, and sex with SVI.

RESULTS

Age, visual condition, stance and sex were all demonstrated to be significant predictors of SVI, with the combination of the predictors explaining 25% of the variance in the SVI.

CONCLUSIONS

These results confirm the balance testing protocol and SVI to be sensitive to age-related changes in balance performance. The results of this study should help future research aimed towards establishing a quick, easy to administer, and readily interpretable instrumented test for assisting with identifying potential balance impairments in older adults who have yet to demonstrate outward deficits.

A Longitudinal Assessment Of Standing Balance In Healthy Adults

Background/Study Context: The study was a longitudinal assessment of age-related changes in standing balance and response strategy usage in healthy adults.

METHODS

Balance of 17 individuals with a mean age of 44.5 years was assessed and then reassessed 19.5 years later. Participants stood on computer-controlled dual-force platforms enclosed by a visual surround and completed six tests in which visual and/or somatosensory information was systematically degraded or eliminated.

RESULTS

Results for each test and a weighted composite balance score revealed no significant change in postural control over the time period studied. However, response strategy scores indicated some significant change with age. Specifically, compensatory movement corrections about the ankle complex increased when standing on a stable support surface with and without vision, and hip-centered corrections were prominent when standing on an unstable surface with eyes open or closed.

CONCLUSION

Increased reliance on response strategy usage with time is interpreted as a compensatory adjustment to age-related increases in postural instability and accounts for the absence of any change in standing balance under different conditions of sensory input.

Associations of Computed Tomography-Based Trunk Muscle Size and Density With Balance and Falls in Older Adults

BACKGROUND

Deficits in balance and muscle function are important risk factors for falls in older adults. Aging is associated with significant declines in muscle size and density, but associations of trunk muscle size and density with balance and falls in older adults have not been previously examined.

METHODS

Trunk muscle size (cross-sectional area) and attenuation (a measure of tissue density) were measured in computed tomography scans (at the L2 lumbar level) in a cohort of older adults (mean ± SD age of 81.9±6.4) residing in independent living communities. Outcome measures were postural sway measured during quiet standing and Short Physical Performance Battery (SPPB) at baseline, and falls reported by participants for up to 3 years after baseline measurements.

RESULTS

Higher muscle density was associated with reduced postural sway, particularly sway velocities, in both men and women, and better Short Physical Performance Battery score in women, but was not associated with falls. Larger muscle size was associated with increased postural sway in men and women and with increased likelihood of falling in men.

CONCLUSIONS

The results suggest that balance depends more on muscle quality than on the size of the muscle. The unexpected finding that larger muscle size was associated with increased postural sway and increased fall risk requires further investigation, but highlights the importance of factors besides muscle size in muscle function in older adults.

Effects of air bottle design on postural control of firefighters

The purpose of this study was to investigate the effect of firefighter's self-contained breathing apparatus (SCBA) air bottle design and vision on postural control of firefighters. Twenty-four firefighters were tested using four 30-minute SCBA bottle designs that varied by mass and size. Postural sway measures were collected using a forceplate under two visual conditions (eyes open and closed) and two stance conditions (quiet and perturbed stances). For perturbed stance, a mild backward impulsive pull at the waist was applied. In addition to examining center of pressure postural sway measures for both stance conditions, a robustness measure was assessed for the perturbation condition. The results suggest that wearing heavy bottles significantly increased excursion and randomness of postural sway only in medial-lateral direction but not in anterior-posterior direction. This result may be due to stiffening of plantar-flexor muscles. A significant interaction was obtained between SCBA bottle design and vision in anterior-posterior postural sway, suggesting that wearing heavy and large SCBA air bottles can significantly threaten postural stability in AP direction in the absence of vision. SCBA bottle should be redesigned with reduced weight, smaller height, and COM closer to the body of the firefighters. Firefighters should also widen their stance width when wearing heavy PPE with SCBA.

Ocena równowagi kobiet po 60 roku życia/ Assessment of Balance women over 60 years of age

Wstęp: Prawidłowa rownowaga jest funkcją warunkującą właściwie wykonywanie czynności z zakresu dnia codziennego. Związane z wiekiem osłabienie reakcji sensorycznych i ruchowych, może spowodować niestabilność postawy oraz zwiększone ryzyko upadkow.

Celem pracy jest określenie rożnic w wartościach parametrow charakteryzujących rownowagę kobiet po 60 roku życia.

Materiał i metody: Do badań przystąpiło łącznie 180 kobiet: 98 kobiet w wieku od 60 do 92 lat (x= 71 lat) oraz 82 kobiety w wieku od 21 do 26 lat (x= 22 lata). Przy użyciu platformy stabilometrycznej, oceniono rownowagę pozycji stojącej w probie z oczami otwartymi oraz zamkniętymi. Oceniono 6 rożnych parametrow ruchu środka nacisku stop (COP).

Wyniki: Analiza statystyczna wykazała istotne rożnice w większości badanych parametrow rownowagi kobiet po 60 roku życia w porownaniu do kobiet z grupy kontrolnej.

Wnioski: 1) Wraz z wiekiem zachodzą istotne zmiany w procesie utrzymywania rownowagi powodujące rosnący deficyt stabilności ciała. 2) Kobiety po 60 roku życia wykazują gorszą stabilność postawy niż kobiety młodsze w zakresie każdego analizowanego parametru z wyjątkiem wychyleń w płaszczyźnie czołowej.

Gait disturbances as specific predictive markers of the first fall onset in elderly people: a two-year prospective observational study

Falls are common in the elderly, and potentially result in injury and disability. Thus, preventing falls as soon as possible in older adults is a public health priority, yet there is no specific marker that is predictive of the first fall onset. We hypothesized that gait features should be the most relevant variables for predicting the first fall. Clinical baseline characteristics (e.g., gender, cognitive function) were assessed in 259 home-dwelling people aged 66 to 75 that had never fallen. Likewise, global kinetic behavior of gait was recorded from 22 variables in 1036 walking tests with an accelerometric gait analysis system. Afterward, monthly telephone monitoring reported the date of the first fall over 24 months. A principal components analysis was used to assess the relationship between gait variables and fall status in four groups: non-fallers, fallers from 0 to 6 months, fallers from 6 to 12 months and fallers from 12 to 24 months. The association of significant principal components (PC) with an increased risk of first fall was then evaluated using the area under the Receiver Operator Characteristic Curve (ROC). No effect of clinical confounding variables was shown as a function of groups. An eigenvalue decomposition of the correlation matrix identified a large statistical PC1 (termed “Global kinetics of gait pattern”), which accounted for 36.7% of total variance. Principal component loadings also revealed a PC2 (12.6% of total variance), related to the “Global gait regularity.” Subsequent ANOVAs showed that only PC1 discriminated the fall status during the first 6 months, while PC2 discriminated the first fall onset between 6 and 12 months. After one year, any PC was associated with falls. These results were bolstered by the ROC analyses, showing good predictive models of the first fall during the first six months or from 6 to 12 months. Overall, these findings suggest that the performance of a standardized walking test at least once a year is essential for fall prevention.

First trial reactions and habituation rates over successive balance perturbations in Parkinson's disease

BACKGROUND

Balance control in Parkinson's disease is often studied using dynamic posturography, typically with serial identical balance perturbations. Because subjects can learn from the first trial, the magnitude of balance reactions rapidly habituates during subsequent trials. Changes in this habituation rate might yield a clinically useful marker. We studied balance reactions in Parkinson's disease using posturography, specifically focusing on the responses to the first, fully unpractised balance disturbance, and on the subsequent habituation rates.

METHODS

Eight Parkinson patients and eight age- and gender-matched controls received eight consecutive toe-up rotations of a support-surface. Balance reactions were measured with a motion analysis system and converted to centre of mass displacements (primary outcome).

RESULTS

Mean centre of mass displacement during the first trial was 51% greater in patients than controls (P=0.019), due to excessive trunk flexion and greater ankle plantar-flexion. However, habituated trials were comparable in both groups. Patients also habituated slower: controls were fully habituated at trial 2, whereas habituation in patients required up to five trials (P=0.004). The number of near-falls during the first trial was significantly correlated with centre of mass displacement during the first trial and with habituation rate.

CONCLUSIONS

Higher first trial reactions and a slow habituation rate discriminated Parkinson's patients from controls, but habituated trials did not. Further work should demonstrate whether this also applies to clinical balance tests, such as the pull test, and whether repeated delivery of such tests offers better diagnostic value for evaluating fall risks in parkinsonian patients.

Altered postural control in persons with cognitive impairment during visual feedback tasks

We compared postural stability with eyes open (EO) and with visual feedback (VFB) in 15 elderly subjects with cognitive impairment (SwCI) and 17 controls. Postural stability was evaluated using the center-of-pressure (COP) mean radius and velocity, while postural strategies by the frequency and damping of the difference between the COP and the center-of-mass (COM) signals. Performance in the VFB trials was measured by the ratio of time spent by the COP inside the target on the screen to the total trial duration. With EO, both groups demonstrated similar postural stability and strategies. The time spent inside the target during VFB was significantly higher in controls than in SwCI. The VFB did not affect the mean radius in either group, nor velocity and frequency in SwCI, however it increased the mean velocity and frequency in controls. Besides, the VFB increased damping significantly more in the SwCI than in controls. These findings indicate that controls adequately responded to the demands of VFB and used efficient strategy of postural control. In contrast, the SwCI seemed to have lost the natural capability to use augmented feedback demonstrating impaired sway control and deficit of sensory integration. All these symptoms of posture control disorders could be objectively identified by the COP mean velocity and the COP-COM frequency and damping. Increased damping in controls during VFB task may account for early signs of cognitive impairment that cannot be captured by standard tests.

A review of balance and gait capacities in relation to falls in persons with intellectual disability

Limitations in mobility are common in persons with intellectual disabilities (ID). As balance and gait capacities are key aspects of mobility, the prevalence of balance and gait problems is also expected to be high in this population. The objective of this study was to critically review the available literature on balance and gait characteristics in persons with ID. Furthermore, the consequences of balance and gait problems in relation to falls were studied, as well as the trainability of balance and gait in persons with ID. The systematic literature search identified 48 articles to be included in this review. The literature consistently reports that balance and gait capacities are affected in persons with ID compared to their age-matched peers. These problems start at a young age and remain present during the entire lifespan of persons with ID, with a relatively early occurrence of age-related decline. From these results a conceptual model was suggested in which the development of balance and gait capacities in the ID population across the life span are compared to the general population. Regarding the second objective, our review showed that, although the relationship of balance and gait problems with falls has not yet been thoroughly investigated in persons with ID, there is some preliminary evidence that these aspects are also important in the ID population. Finally, this review demonstrates that balance and gait are potentially trainable in persons with ID. These results suggest that falls might be prevented with ID-specific exercise interventions.

Effects of an unstable shoe construction on balance in women aged over 50 years

BACKGROUND

Shoes with an unstable sole construction are commonly used as a therapeutic tool by physiotherapists and are widely available from shoe and sporting goods retailers. The aim of this study was to investigate the effects of using an unstable shoe (Masai Barefoot Technology) on standing balance, reactive balance and stability limits.

METHODS

Thirty-one subjects agreed to participate in the study and underwent balance tests on three different occasions. After test occasion one (baseline) 20 subjects received Masai Barefoot Technology shoes and were requested to wear them as much as possible for the remaining eight weeks of the study. Three specific balance tests were administered on each test occasion using a Pro Balance Master (NeuroCom International Inc., Oregon, USA). Tests included; a modified sensory organization test, reactive balance test and limits of stability test.

FINDINGS

Subjects in the intervention group significantly improved their performance on elements of all three tests however results on these variables were not demonstrated to be significantly better than the control group. No significant differences were observed across testing occasions in the control group.

INTERPRETATION

Results from the present study suggest that, for this group of individuals, use of unstable footwear may improve certain aspects of balance.

Sensory organization test in elderly patients with and without vestibular dysfunction

CONCLUSIONS

Elderly subjects without vestibular dysfunction had an overall worse performance as compared with the group of normal adults, confirming that age has a negative impact on balance. The group of elderly subjects with vestibular dysfunction had more important balance alterations than those without, confirming that vestibular dysfunction has a major impact on balance control in the elderly. The visual and vestibular systems presented more important functional changes with ageing than the somatosensory system.

OBJECTIVE

The main sensory input comes from the visual, vestibular and somatosensory systems; all of them may present changes due to ageing. This study aimed to investigate the performance of vestibular, visual and somatosensory systems in aged subjects with or without vestibular dysfunction, as compared to normal adults.

SUBJECTS AND METHODS

Dynamic posturography was used in 60 elderly subjects without vestibular dysfunction (Gaa), 60 with vestibular dysfunction (Gas) and 58 normal adults (Gn).

RESULTS

For condition 1 and 2 Gn performed significantly better than Gaa and Gas, with no difference between the latter. In conditions 4, 5 and 6 the performance of Gn was statistically superior to that of Gaa, which in turn, was better than that of Gas. The somatosensory responses showed no significant differences between the three groups. The performance of visual and vestibular systems showed progressive dysfunction: Gn did better than than Gaa, and Gaa did better than Gas.

Tell me your vestibular deficit, and i'll tell you how you'll compensate

Most patients with unilateral vestibular loss exhibit a similar static and dynamic vestibular syndrome consisting of vestibulo-ocular, posturolocomotor, and perceptive deficits. This vestibular syndrome recovers more or less completely and more or less rapidly over time. One open question is whether recovery mechanisms differ according to vestibular pathology and/or patients. It is reported here (1) data from three different cat models of unilateral vestibular loss reproducing vestibular pathology with sudden (unilateral vestibular neurectomy [UVN] model), gradual (unilateral labyrinthectomy [UL] model), or reversible (tetrodotoxine [TTX]) model) loss of vestibular function, and (2) clinical observations in a population of unilateral vestibular loss patients suffering the same pathology (Menière's disease). Animal models show that time courses and mechanisms of recovery depend on the type of vestibular deafferentation, and clinical findings show that Menière's patients compensate their postural and perceptive deficits using different vicarious processes. Taken together, results point to a more complex picture of compensation after unilateral vestibular loss, which cannot be reduced either to a common recovery mechanism or to a single process identical for all individuals. These findings should guide physiotherapists in treatment and rehabilitation for vestibular deficits.

Assessment of diagnostic accuracy of foam posturography for peripheral vestibular disorders: analysis of parameters related to visual and somatosensory dependence

OBJECTIVES

Simple tests to detect peripheral vestibulopathy might be practically useful before conducting elaborate examinations. The purpose of this study was to assess the diagnostic accuracy of foam posturography for peripheral vestibulopathy, with emphasis on visual and somatosensory dependence.

METHODS

Two-legged stance tasks were conducted in patients with unilateral (n=68) and bilateral (n=16) vestibulopathy and healthy controls (n=66), under four conditions; eyes open with and without the foam rubber, and eyes closed with and without the foam rubber.

RESULTS

The values of six parameters; the velocity of movement of the center of pressure (COP) and envelopment area tracing by the movement of the COP in eyes closed/foam rubber, the Romberg's ratios of velocity and area with foam rubber, and the foam ratios (ratios of a measured parameter with to without the foam rubber), of velocity and area in eyes closed, were significantly higher in unilateral and bilateral vestibulopathy compared with the control (p<0.001). The area under the receiver operating characteristic curve for the Romberg's ratio of velocity with the foam rubber was the largest.

CONCLUSIONS

Foam posturography detected high levels of visual and somatosensory dependence in patients with vestibulopathy.

SIGNIFICANCE

Foam posturography is useful for preliminary assessment of possible peripheral vestibulopathy.

Poor vision accompanied with other sensory impairments as a predictor of falls in older women

OBJECTIVES

we studied visual acuity (VA) and co-existing hearing impairment and poor standing balance as predictors of falls.

DESIGN

prospective study with 1-year follow-up.

SETTING

research laboratory and residential environment.

PARTICIPANTS

428 women aged 63-76 years from the Finnish Twin Study on Aging.

MEASUREMENTS

participants were followed up for incidence of falls over 1 year. VA, hearing ability and standing balance were assessed at the baseline. The incidence rate ratios (IRR) for falls were computed using the negative binomial regression model.

RESULTS

during the follow-up, 47% of participants experienced a fall. After adjusting for age and interdependence of twin sisters, participants with vision impairment (VA of <1.0) but no other sensory impairments had a higher, but non-significant, risk for falls compared to persons with normal vision (IRR 1.5, 95% CI 0.6-4.2). Co-existing vision impairment and impaired balance increased the risk (IRR 2.7, 95% CI 0.9-8.0), as also did co-existing vision and hearing impairment (IRR 4.2, 95% CI 1.5-11.3), compared to those with normal vision. Among persons with all three impairments, the IRR for falls increased to 29.4 (95% CI 5.8-148.3) compared to participants with good vision.

CONCLUSION

the impact of vision impairment on fall risk was higher when accompanied with other sensory and balance impairments, probably because the presence of other impairments prevented the reception of compensatory information about body posture and environment being received from other sensory sources. When aiming to prevent falls and their consequences in older people, it is important to check whether poor vision is accompanied with other impairments.

Postural adaptations to repeated optic flow stimulation in older adults

The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of three conditions were performed: (1) constant 12 cm optic flow amplitude (24 cm peak-to-peak), (2) constant 4 cm amplitude (8 cm p-t-p), and (3) a transition in amplitude from 4 to 12 cm. The average power of head sway velocity (P(vel)) was calculated for consecutive 5s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the P(vel). P(vel) was greater in older adults in all conditions (p<0.001). During the 12 cm constant amplitude trials, within-trial adaptation occurred for all subjects, but there were differences in the between-trial habituation. P(vel) of the older adults decreased significantly between all 3 trials, but decreased only between Trials 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12 cm did not significantly change, older adults had an increase in P(vel) following the transition, ranging from 6.5 dB for the first trial to 3.4 dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization.

Impact of exercise on seniors' motor control response to external dynamics

Research on postural stability, motor control, and fall occurrence in seniors is common, but few studies address the influence of exercise and external dynamics on elderly balance. Using pre- and post-training tests, the effects of a Fitball exercise program on performance in eight subjects was documented. The exercise program focused on improving dynamic balance and postural stability of seniors. To evaluate progress-related changes, pre- and post-tests in a dynamic environment were applied. Center of gravity (COG) excursion, catch success rate, and balance success rate were quantified, and synchronized data collection of 3D motion capture (VICON v8i) and ground reaction force (2 KISTLER platforms) was analyzed. During pre- and post-tests, participants stood in a walklike stance and were asked to catch a weighted ball, which dropped unexpectedly. Results showed no significant changes in balance success rate. Significant improvements were found, however, in both COG control and catch success rate following training (p<0.05).

Posturography and Risk of Recurrent Falls in Healthy Non-Institutionalized Persons Aged Over 65

BACKGROUND

A poor postural stability in older people is associated with an increased risk of falling. The posturographic tool has widely been used to assess balance control; however, its value in predicting falls remains unclear.

OBJECTIVE

The purpose of this prospective study was to determine the predictive value of posturography in the estimation of the risk of recurrent falls, including a comparison with standard clinical balance tests, in healthy non-institutionalized persons aged over 65.

METHODS

Two hundred and six healthy non-institutionalized volunteers aged over 65 were tested. Postural control was evaluated by posturographic tests, performed on static, dynamic and dynamized platforms (static test, slow dynamic test and Sensory Organization Test [SOT]) and clinical balance tests (Timed 'Up & Go' test, One-Leg Balance, Sit-to-Stand-test). Subsequent falls were monitored prospectively with self-questionnaire sent every 4 months for a period of 16 months after the balance testing. Subjects were classified prospectively in three groups of Non-Fallers (0 fall), Single-Fallers (1 fall) and Multi-Fallers (more than 2 falls).

RESULTS

Loss of balance during the last trial of the SOT sensory conflicting condition, when visual and somatosensory inputs were distorted, was the best factor to predict the risk of recurrent falls (OR = 3.6, 95% CI = 1.3-10.11). Multi-Fallers showed no postural adaptation during the repetitive trials of this sensory condition, contrary to Non-Fallers and Single-Fallers. The Multi-Fallers showed significantly more sway when visual inputs were occluded. The clinical balance tests, the static test and the slow dynamic test revealed no significant differences between the groups.

CONCLUSION

In a sample of non-institutionalized older persons aged over 65, posturographic evaluation by the SOT, especially with repetition of the same task in sensory conflicting condition, compared to the clinical tests and the static and dynamic posturographic test, appears to be a more sensitive tool to identify those at high-risk of recurrent falls.

Altersabhängige Unterschiede bei funktionellen Tests zur Beurteilung des Sturzrisikos bei Patienten mit Kniegelenksbeschwerden

In the present cross-sectional study the results of three tests to assess the risk of falling were examined for a correlation with advancing age of the participants. Each of the 188 community dwelling active participants aged 40 years or older with a history of knee pain performed the Timed Up and Go (TUG), the Performance Oriented Mobility Assessment (POMA, "Tinetti Test") and a less established simple test of dynamic balance, the Four Square Step Test (FSST). Age-related differences in performance in the Timed Up and Go and the Performance Oriented Mobility Assessment have been shown in previous studies and are also present in this sample. For the Four Square Step Test an association of test performance and age has been shown for the first time in this study. Further investigation is required to determine the quality of these three tests regarding their ability to assess the risk of falling in patients with knee pain.

Multisensory reweighting of vision and touch is intact in healthy and fall-prone older adults

Unexplained falls in older adults are thought to arise from subtle deficits in multiple components of the postural control system, including peripheral sensory loss and central sensory processing. One commonly proposed central sensory processing deficit is a decline in the adaptive use of changing or conflicting sensory inputs for estimating body dynamics, i.e., multisensory reweighting. We examined the assumption of impaired multisensory reweighting in healthy and fall-prone older adults using quantitative methods that have previously demonstrated reweighting in young adults. Standing subjects were exposed to simultaneous medio-lateral oscillatory visual and fingertip touch inputs at varying relative amplitudes. No group differences in overall levels of vision and touch gain were found. Both healthy and fall-prone older adults demonstrated the same pattern of adaptive gain change as healthy young adults. Like the young adults, both elderly groups displayed clear evidence of intra- and inter-sensory reweighting to both vision and touch motion stimuli. These data suggest that, for small amplitude vision and touch stimuli, the central sensory reweighting adaptation process remains intact in healthy and fall-prone older adults with sufficiently intact peripheral sensation.

Postural Balance in a Random Sample of 7,979 Subjects Aged 30 Years and Over

BACKGROUND

Reliable normative data for force platform measurements of postural balance have not been available.

METHODS

Data on postural balance were collected from a representative nationwide sample of a Finnish population aged >or=30 years (n = 7,979). As part of a comprehensive health survey (Health 2000), postural balance was measured with the help of a force platform system in four test conditions: normal standing with eyes open and closed (both for 30 s), semi-tandem (20 s) and tandem stand with eyes open (20 s). In addition, balance abilities were also evaluated by a non-instrumented field test.

RESULTS

The main findings of this study indicated that the differences in balance between subjects belonging to different age categories were apparent already among young and middle-aged subjects. This is true, however, only for the more accurate force platform measurements, as the field test showed a clear ceiling effect up to 60 years of age. At higher ages both methods indicated a further, accelerating decline in balance function. In most cases, males tended to have more pronounced sway, as indicated by the speed and amplitude aspects of the movement of the center of pressure during the force platform registrations and these differences were larger in the older age groups. In contrast, in the field test a larger proportion of males were able to achieve the highest category (10 s in tandem stand) and the proportion of subjects unable to stand for a minimum of 10 s feet side by side was larger among females than males. These observations may partly be due to differences in the participation/acceptable performance in the different tests. In addition, the field test and force platform measurements may partially reflect different aspects of balance abilities.

CONCLUSION

The results of the present study provide normative values for force platform balance tests at an age of 30 years and above. Deterioration in balance function clearly starts at relatively young ages and further accelerates from at about 60 years upwards. Due to systematic differences between males and females, separate normative values for both sexes are needed. Due to marked ceiling effects the field test can only be recommended for older individuals, aged >/=60. On the other hand, force platform registrations in the more demanding tests (semi-tandem and tandem stands) suffer from floor effects in the oldest age groups.

Calf muscle-tendon properties and postural balance in old age

We tested the hypothesis that compromised postural balance in older subjects is associated with changes in calf muscle-tendon physiological and mechanical properties. Trial duration and center of pressure (COP) displacements were measured in 24 younger (aged 24+/-1 yr), 10 middle-aged (aged 46+/-1 yr), and 36 older (aged 68+/-1 yr) healthy subjects under varying levels of postural difficulty. Muscle-tendon characteristics were assessed by dynamometry, twitch superimposition, and ultrasonography. In tandem and single-leg stances, trial duration decreased (<or=65% lower, P<0.001) and COP displacements increased (<or=90% higher, P<0.05) with age. Muscle strength, size, activation capacity, and tendon mechanical properties decreased with age by 55, 13, 13, and 36-48%, respectively (P<0.05). Regressions with these parameters and balance indexes were significant (P<0.05) for single-leg and tandem (0.69<r2<0.90) postures only, indicating that the age-related changes in muscle-tendon characteristics may explain the majority of the variance in balance performance during tasks more difficult than habitual bipedal stance.

Force Platform Measurements as Predictors of Falls among Older People – A Review

BACKGROUND

Poor postural balance is one of the major risk factors for falling. A great number of reports have analyzed the risk factors and predictors of falls but the results have for the most part been unclear and partly contradictory. Objective data on these matters are thus urgently needed. The force platform technique has widely been used as a tool to assess balance. However, the ability of force platform measures to predict falls remains unknown.

OBJECTIVE

The purpose of this systematic review was to extract and critically review the findings of prospective studies where force platform measurements have been used as predictors of falls among elderly populations.

METHODS

The study was done as a systematic literature review. PubMed, the Cochrane Central Register of Controlled Trials, and CINAHL databases from 1950 to April 2005 were used. The review includes prospective follow-up studies using the force platform as a tool to measure postural balance.

RESULTS

Nine original prospective studies were included in the final analyses. In five studies fall-related outcomes were associated with some force platform measures and in the remaining four studies associations were not found. For the various parameters derived on the basis of the force platform data, the mean speed of the mediolateral (ML) movement of the center of pressure (COP) during normal standing with the eyes open and closed, the mean amplitude of the ML movement of the COP with the eyes open and closed, and the root-mean-square value of the ML displacement of COP were the indicators that showed significant associations with future falls. Measures related to dynamic posturography (moving platforms) were not predictive of falls.

CONCLUSION

Despite a wide search only a few prospective follow-up studies using the force platform technique to measure postural balance and a reliable registration of subsequent falls were found. The results suggest that certain aspects of force platform data may have predictive value for subsequent falls, especially various indicators of the lateral control of posture. However, the small number of studies available makes it difficult to draw definitive conclusions.

Undisturbed upright stance control in the elderly: Part 2. Postural-control impairments of elderly fallers

A common way of predicting falling risks in elderly people can be to study center of pressure (CP) trajectories during undisturbed upright stance maintenance. By estimating the difference between CP and center of gravity (CG) motions (CP - CGv), one can estimate the neuromuscular activity. The results of this study, which included 34 sedentary elderly persons aged over 75 years (21 fallers and 13 nonfallers), demonstrated significantly increased CGh and CP - CGv motions in both axes for the fallers. In addition, the fallers presented larger CGh motions in the mediolateral axis, suggesting an enlarged loading-unloading mechanism, which could have reflected the adoption of a step-initiating strategy. As highlighted by fractional Brownian motion modeling, the distance covered by the CP - CGv motions before the successive control mechanisms switched was enhanced for the fallers in both axes, therefore increasing the risk that the CG would be outside of the base of support.

Understanding falls in osteoporosis: the viscoelastic modeling perspective

Unsteadiness and increased postural sway predispose individuals with osteoporosis to falling. We examined this relationship from a biomechanical perspective using a viscoelastic model. Specifically, we investigated the center-of-pressure (COP) in quiet stance in 37 postmenopausal women (aged 42-79 years), diagnosed with osteopenia or osteoporosis and who engaged in a range of activity levels. Subjects stood on a force platform for two 20s intervals: one with eyes open (EO) and the other with eyes closed (EC). The COP signals were used to compute traditional measures of sway: standard deviation, range, and mean velocity. Based on the difference between the COP and its smoothed representation, we used the "COP minus center-of-mass" signal to compute selected properties of postural mechanics (stiffness and viscosity) and dynamics (frequency and damping) of stance. Sway variability and incidence of falls were not correlated even though our subjects displayed higher sway than age-matched subjects from other studies. Bone density was correlated with frequency in the mediolateral (ML) plane with EO (r=0.50, p<0.002). Irrespective of age, the decrease in postural frequency and increase in postural viscosity in the ML plane were determinants of imbalance and accounted for 18% and 8% of the variance, respectively. With EC, an additional 10% of the variance was contributed by the ML range. The increased ML viscosity was the sole predictor of falls accounting for 20% of the variance of the tendency to fall. Thus, ML frequency plays a fundamental role in preserving balance in that a low value is an important predictor of falls. Finally, although being physical activity may reduce sway, physical activity fails to improve poor postural strategies. To conclude, increases in viscosity and range elucidate further the unique strategy of ML body sway in individuals with osteopenia or osteoporosis and provide insight into how posture may be maintained by those who fear falling.

Undisturbed Upright Stance Control in the Elderly: Part 1. Age-Related Changes in Undisturbed Upright Stance Control

The authors investigated age-related changes in postural control in 33 healthy young adults (18-31 years), 29 seniors (62-75 years), and 22 elderly people (75-96 years). A force platform recorded the results. The horizontal motions of the center of gravity (CGh) and their difference in the plane of support CP - CGv were deduced from the complex center of pressure (CP) trajectories. With fractional Brownian modeling, one can establish that the aging process seems to induce a transition phase in which seniors take more time to initiate the corrective process in the mediolateral (ML) axis than do younger people. The elderly develop a new strategy characterized by the mobilization of higher neuromuscular energy to maintain equilibrium. In the ML axis, the larger displacements could be caused mainly by a hip strategy that could facilitate step initiation. In the anteroposterior (AP) axis, seniors and elderly individuals maintain a relative ability to stabilize their CG into the base of support compared with younger people.

Validating the Berg Balance Scale for patients with Parkinson’s disease: A key to rehabilitation evaluation

OBJECTIVE

To assess the criterion-related validity of the Berg Balance Scale (BBS) in subjects with Parkinson's disease (PD).

DESIGN

Prospective, correlational analysis between the BBS and accepted measures of PD motor and functional impairment.

SETTING

The federally funded PD research center, an interdisciplinary center of excellence for people with PD within a Veterans Affairs medical center.

PARTICIPANTS

Thirty-eight men (average +/- standard deviation, 71.1+/-10.5 y) with confirmed PD. Their initial diagnosis had been made on average 5.8+/-3.6 years earlier. All could stand or walk unassisted and had mild to moderate disability. Patients who could not ambulate without assistive devices were excluded.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Correlational analyses between the BBS and the Unified Parkinson's Disease Rating Scale (UPDRS) motor scale, Modified Hoehn and Yahr Staging (Hoehn and Yahr) Scale, and the Modified Schwab and England Capacity for Daily Living Scale (S&E ADL Scale).

RESULTS

BBS score showed significant correlations with indicators of motor functioning, stage of disease, and daily living capacity. BBS score was inversely associated with the UPDRS motor score (-.58, P <.005), Hoehn and Yahr Scale staging (-.45, P <.005), and S&E ADL Scale rating (.55, P <.005). In all 3 correlations, lower scores on the BBS (indicating greater balance deficits) correlated with higher UPDRS scores (indicating greater motoric or functional impairment).

CONCLUSIONS

Results support the criterion-related validity of the BBS. Its utility in other balance conditions of older adults has been established. Rehabilitation interventions have been shown to improve the balance deficits associated with PD. Early referral and periodic reassessment is vital to achieving and maintaining improvements. Our research results agree with other published research in suggesting that the BBS may be used as a screening tool and ongoing assessment tool for patients with PD.

Postural balance and health-related factors in middle-aged and older women with injurious falls and non-fallers

BACKGROUND AND AIMS

Older fallers aged over 70 years have shown impaired balance abilities, but it is unclear if impairment in balance control can be detected among fallers who are in their 50's and 60's. The aim of this study was to analyze possible differences in balance control and other health-related factors between female fallers and non-fallers aged 50-68 years.

METHODS

Women 50-68 years of age (N=40) who had fallen outside and needed medical attention were recruited through a larger fall accident study. Non-fallers (N=97) were women representing the same age group who had not fallen during the preceding 12 months. A battery of standing force platform balance tests were administered together with an interview on health status, use of medication, dizziness, vision, hearing, and physical activity.

RESULTS

Significant differences were not found between women with injurious falls and non-fallers in the various balance tests. In the younger age group (50-58 years), chronic illnesses, use of medication, dizziness, and self-reported problems with vision and hearing were more common in fallers than in non-fallers.

CONCLUSIONS

Our results suggest that, in active and independent women aged 50-68 years, it is not possible to use standing force platform balance tests to detect differences between fallers and non-fallers. However, younger women (50-58 years) with injurious falls reported more health-related problems than other groups, a fact which should be taken into consideration to prevent further development of fall-related problems.

The effect of aging on postural stability: a cross sectional and longitudinal study

AIMS OF THE STUDY

Only a good knowledge of the effects of age on postural stability allows differentiating between physiological aging and pathologies leading to its impairment. The aims of this study were to define the posturographic parameters which best reflected the effects of aging on postural stability and to determine the slope of postural stability impairment related to aging.

PATIENTS AND METHODS

Postural stability of 50 normal volunteers aged 25-83 years (55.4) was studied with one Kistler force plate. Subjects were asked to stand for 30 s on two-legged stance, eyes open then closed. The center of pressure displacement (COPd) and velocities (COPv), in the antero-posterior (x) and the medio-lateral (z) axis, the sway axis, and the integral of COP displacement vs. time were computed. Eleven subjects were retested at 3 and 6 months to estimate the reliability of posturographic measurements. In addition, 28 subjects aged 25-83 years (60.2) were retested 2.2 years after their first posturographic assessment.

RESULTS

COPxv best reflected postural stability impairment with aging. Closure of the eyes increased the variance of the results. This change was higher in subjects more than 60 years old: 0.019-0.157 cm2 s(-2) than in younger ones: 0.011-0.043 cm2 s(-2). Retesting at 3 and 6 months showed a reliability of 79%. According to the cross-sectional part of the study, the slope of postural stability impairment with aging was estimated at 0.0038 cm/s/year. These results were confirmed by the longitudinal part of the study, which showed that COPxv increased from 0.66-0.75 cm/s/year (P = 0.0001) (slope = 0.0041 cm/s/year).

CONCLUSION

(1) Measurement of COPxv, on two-legged stance, is a simple and reliable way to assess postural stability. (2) Thanks to both a cross sectional and a longitudinal study, the rate of postural stability impairment due to aging was precisely estimated, which will be useful to help distinguishing between the part of postural stability impairment attributable to aging from the one due to neuro-degenerative diseases.

Clinical tests for the evaluation of postural instability in patients with parkinson’s disease11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated

OBJECTIVE

To determine which test for postural instability in Parkinson's disease (PD) is reliable, valid, and easy to perform in a clinical setting.

DESIGN

Cross-sectional reliability and validity study.

SETTING

Academic center for movement disorders.

PARTICIPANTS

Forty-two patients with PD and 15 controls. Based on the results of a structured interview, the patients were divided in PD-unstable (n=22) and PD-stable (n=20) groups.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Several variants of the retropulsion test with differences in execution and scoring. Responses were scored on 5 different rating scales (ratings of Nutt, Bloem, Pastor; the Unified Parkinson's Disease Rating Scale [UPDRS]; the Short Parkinson Evaluation Scale). These tests were compared with steady-stance positions.

RESULTS

The interrater reliability was high for most ratings, with weighted kappa ranging from.63 for the UPDRS to.98 for both the Pastor rating and steady-stance positions. Most ratings distinguished between the groups. However, the Nutt rating had the highest overall predictive accuracy, with a sensitivity of.63 and a specificity of.88.

CONCLUSIONS

The most valid test for postural stability in PD was an unexpected shoulder pull, executed once, with taking more than 2 steps backward considered abnormal. This retropulsion test is easy to use in a clinical setting.

[Postural strategies and falls in elderly and in parkinsonism]

OBJECTIVE

To use a posture analysis to show the evolution of postural pattern connected with falls.

MATERIAL AND METHOD

It is a prospective study on two groups of 16 persons of more than 60 years. A group concerns 16 small disability off drug parkinsonian patients, a group concerns 16 healthy witnesses. All the persons benefited from a posture recording by means of a force platform and were followed during 1 year.

RESULTS

Data analysis underlines three groups of persons corresponding to three postural patterns, independently of the presence of Parkinson disease. A group (n = 18) did not contain fallers, the second (n = 10 ) contained 20% of fallers, the third (n = 4) contained 100% of fallers. Differences between the groups were identified on 16 posturographic parameters.

DISCUSSION

A group has a good functional value and one does not record any fall. Its characteristics, which correspond to a category of persons who compensate well for the phenomena of ageing, are found in the literature. A group has an intermediate functional value and regrets 20% of fallers. Kinetic profile reveals a tendency to the stiffness of the posture. This group is going to operate rather ankle strategies. A group has an inferior functional value and regrets 100% of fallers. Kinetic profile seems disrupted and not to be able to adapt itself in a satisfactory way to the situation otherwise than by stereotypical reactions. This group is going to operate systematically much less stabilizing hip strategies.

CONCLUSION

A close determinism between physiological neuromotor ageing and Parkinson disease does exist. We showed with a prospective follow-up, the arisen of fall and showed the evolution of postural patterns related to fall. It appears as well that evolution mainly follows three stages leading from a small risk of fall gait pattern to a major risk of fall gait pattern.