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At least 109 records · Page 6Linked to original sources
PubMed2004

Reliance on visual information after stroke. Part I: Balance on dynamic posturography.

OBJECTIVE: To test the hypothesis that postural imbalance after stroke may be caused by inability to use pertinent somatosensory, vestibular, or visual information. DESIGN: Description of the sensory organization of patients with hemiplegia. SETTING: Public rehabilitation center in France. PARTICIPANTS: Forty patients with hemiplegia after a single hemisphere stroke who were at least 12 months post stroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The patients performed computerized dynamic posturography (EquiTest), which is designed to assess a patient's ability use sensory inputs separately and to effectively suppress inaccurate inputs in case of sensory conflict. Body stability under each of 6 sensory conditions was assessed by an equilibrium score (ES). RESULTS: In conditions of altered somatosensory information, with visual deprivation (ES5) or visuovestibular conflict (ES6), the median scores for patients with hemiplegia (ES5-43; ES6-20) were significantly lower than those for normal subjects (ES5-69; ES6-67). CONCLUSIONS: Many patients with hemiplegia seem to rely on visual input. The mechanism of this excessive visual reliance is discussed. Rehabilitation programs of postural control for the patients with hemiplegia should take into account the possible impairment of sensory organization and should include exercises to be performed under conditions of sensory input deprivation and sensory conflict.

Cerebral Cortex↗
PubMed2006

The relationship between falls history and computerized dynamic posturography in persons with balance and vestibular disorders.

OBJECTIVE: To describe the relationship between Sensory Organization Test (SOT) scores and reported falls in persons with vestibular and balance disorders. DESIGN: Descriptive cross-sectional. SETTING: Outpatient tertiary balance and falls clinic. PARTICIPANTS: One hundred physical therapy (PT) charts of people referred to a balance and falls clinic were reviewed. Criteria for inclusion were that the patients had completed the SOT of computerized dynamic posturography (CDP), had a vestibular diagnosis, and had the numbers of falls recorded from patient report within the last 6 months at the initial examination. Rotational chair, caloric testing, oculomotor test, and Activities-Specific Balance Confidence (ABC) results were recorded, if available. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The SOT composite and ABC scores as they related to reports of falls in the last 6 months. RESULTS: The overall proportion of persons with vestibular disorders with positive 6-month history for 1 or more falls was 30% and for recurrent falls (>/=2) was 17%. Vestibular laboratory findings, age, sex, and vestibular diagnosis were not related to reported falls status. Patients who reported multiple falls prior to the PT examination had lower SOT composite scores than patients who reported 1 or no falls in the previous 6 months. The receiver operating characteristic curve identified a composite SOT score of less than 38 as demonstrating the highest likelihood ratio for differentiating between those people who reported no falls in the past 6 months and those who reported 2 or more falls. CONCLUSIONS: Persons who are recurrent fallers perform worse on SOT than either nonfallers or 1-time fallers. CDP performance can help guide the clinician in the development of a safe exercise program.

Accidental Falls↗
PubMed2006

Changing control strategies during standard assessment using computerized dynamic posturography with older women.

The goal of this investigation was to explore the use of spectral analysis to examine the data obtained during computerized dynamic posturography (CDP). In particular, we examined whether spectral analysis would provide more detailed information about underlying postural control strategies and potential learning across conditions and trials of the sensory organization test (SOT). Twenty older women between the ages of 60 and 72 (mean=65.2) were assessed using standard testing protocol. Participants showed significant improvements from the first to the second trials in their equilibrium scores in the more difficult conditions. This finding was reflected in the spectral analysis data by a shift in the frequency distribution towards greater power in the lower frequency range. This frequency change likely reflects a change in the ankle strategy used to maintain balance during the more difficult conditions.

Aged↗
PubMed2005

A markerless sub-pixel motion estimation technique to reconstruct kinematics and estimate the centre of mass in posturography.

A novel method to evaluate postural sway is presented: balance strategies are identified by applying a markerless image processing algorithm to video sequences obtained from commercially available systems. The motion estimation technique for the analysis of video sequences is a coarse to fine procedure based on the block matching algorithm (BMA). The method makes it possible to estimate the movement of selected elements on the scene with a sub-pixel precision. It has been done by applying a bicubic spline interpolation to the coarse results obtained by the BMA. Results achieved through the analysis of synthetic video tests make it possible to determine the accuracy of the proposed sub-pixel algorithm. Figures show how the proposed method can be confidently applied to evaluate postural sway. The proposed method has been applied to videos recorded during orthostatic posture trials in different conditions, and to combined tests where signals from a balance plate have been acquired simultaneously to the video sequence. The results show the usefulness of the proposed approach in order to evaluate balance strategies in posturography.

Algorithms↗
PubMed2002

[Relation between clinical symptoms and the results of a computerized dynamic posturography].

The computerized dynamic posturography (CDP) is a quantitative method for the evaluation of balance function under different conditions that simulates the ones found in normal life. Its applications are centered in the diagnosis and rehabilitation of balance dysfunction. We report a descriptive study on 96 patients with balance disorders who underwent a CDP, stablishing a relation between their main symptoms and the results in the test. A high percentage of patients with symptoms that suggested peripheral vestibular pathology did not present alterations at this level by means of the CDP. However a considerable number of patients who referred symptoms classically related to a non vestibular origin did show an alteration at this level.

Adult↗
PubMed1998

Computerized dynamic posturography: What have we learned from space?

Computerized dynamic posturography (CDP) has been under development since 1970. Several reviews summarize key basic and clinical research studies and outline important clinical uses of CDP along with research applications. This report summarizes new information about the otolith control of posture obtained from the study of astronauts. The dynamics of recovery of postural control upon return from orbital flight provide insight to the peripheral vestibular and central nervous system components of vestibular compensation. The dynamics of postural compensation should aid the clinician in the diagnosis and management of imbalance of vestibular origin.

Adaptation, Physiological↗
PubMed2003

Development of virtual reality stimuli for force platform posturography.

People relying much on vision in the control of posture are known to have an elevated risk of falling. Dependence on visual control is an important parameter in the diagnosis of balance disorders. We have previously shown that virtual reality (VR) methods can be used to produce visual stimuli that affect balance, but suitable stimuli need to be found. In this study, the effect of six different VR stimuli on the balance of 22 healthy test subjects was evaluated using force platform posturography. We report in more detail and expand the results published earlier. According to the tests two of the stimuli have a significant destabilizing effect on balance. In addition a significant displacement effect on the subject's center of pressure (COP) was found. Thus it is shown that the design of VR stimuli to cause different effects on the control of balance is possible.

Adult↗
PubMed1993

Sensory interaction testing in platform posturography.

Mostly techniques measuring the vestibulo-ocular reflex (VOR) have been used for the evaluation of patients with dizziness problems. Some investigators, however, have also tried to take into account the vestibulospinal reflex (VSR). So recording techniques for the Romberg-test have been proposed and called posturography (PG). By interfering with the visual and proprioceptive sensory inputs during this PG-testing one tries to find out how 'sensory interaction' is organized in the balance performance of the patient examined. To interfere with vision, closure of the eyes has been commonly used and to interfere with proprioception, the patient can be put on foam-rubber, which makes the contribution of the foot-ankle proprioception less adequate. These interferences are applied once separately and once combined. The degree of 'abnormality' is assessed by a score-system for parameters surface (S) and velocity (V), which measure the postural sway. A comparison of tests with and without influence on the sensory inputs gives an idea of the sensory interaction. Patients with peripheral vestibular disorders were examined: patients with BPPV, with spontaneous vertigo attacks and with a sudden vestibular deficit. When applying this evaluation technique different formulae or patterns can be found. Firstly complete normal evaluation, which means that there is no influence of the vestibular disturbance upon the PG results. Secondly a normal balance when using all available sensory information, but disturbed balance as soon as one of the sensory inputs is influenced by the test conditions. Thirdly striking destabilization when closing the eyes. Fourthly striking destabilization when misleading the ankle and foot proprioceptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Applications and uses of static and dynamic measurement of posture (posturography)].

Posturography is a very useful clinical instrument to quantify, analyze, and document postural sway and to differentiate patterns of instability that are typical for the different types of lesions encountered within the cerebellum and to differentiate cerebellar ataxia from spinal ataxia. An objective method of measurement like this is most valuable for follow-up studies and the surveillance of therapeutic efficacy. The method of recording short, medium, and long latency reflexes in leg muscles after a sudden tilt of a movable platform toe-up is not only totally atraumatic and fast, but more importantly it gives significant hints towards the possible site of a central lesion in the sensory-motor system.

Cerebellar Ataxia↗
PubMed2006

Influence of nerve of origin and tumor size of vestibular schwannoma on dynamic posturography findings.

CONCLUSION: Condition 5-score (C5S) and vestibular ratio (VER) correlate, but condition-6-score (C6S) and mean overall balance score (MOBS) do not, with the size of an inferior vestibular nerve (IVN) vestibular schwannoma (VS). In IVN VS patients the visual system plays a major role in the maintenance of postural stability. OBJECTIVES: To test whether the size of a superior vestibular nerve (SVN) or IVN VS, as measured on MRI scans, correlates with computerized dynamic platform posturography (CDPP) findings and whether CDPP findings could preoperatively predict the nerve of origin of the VS. PATIENTS AND METHODS: This was a retrospective study. Seventy-five consecutive VS patients were evaluated. C5S, C6S, VER, and MOBS were evaluated. Spearman's rank correlation coefficients were calculated between the tumor's larger dimension and each of the four parameters for SVN and IVN VS. The nerve of VS origin was identified intraoperatively. To test for differences between CDPP findings of the SVN and IVN groups of VS patients, the Wilcoxon-Mann-Whitney sum rank test was applied. RESULTS: Larger dimension of VS was correlated with C5S and VER in IVN VS patients (r = - 0.358, p=0.008 and r = - 0.356, p=0.008, respectively). Neither C6S nor MOBS showed any significant correlation with the tumor's larger dimension. None of the four scores showed any significant difference between the SVN and IVN groups of VS patients.

Female↗
PubMed1998

Validity of visual stabilization conditions used with computerized dynamic platform posturography.

Temporal and spatial relationships between head motion and tilt of a visual surround were evaluated in conditions 3 and 6 of the sensory organization test (SOT) to determine the validity of visual stabilization during computerized dynamic platform posturography (CDP). Seven healthy subjects participated (mean age 42.4 years, SD = 19 years, range 25-72 years). Sagittal head translation and head pitch were evaluated separately with respect to displacement of the visual surround. Overall, the mean correlation between sagittal head motion and surround tilt was r = 0.68 for C3 and r = 0.93 for C6. The average phase (aggregate findings supported with trial-by-trial analysis), however, showed that sagittal head displacement leads motion of the visual surround ( + 452 ms for C3 and + 250 ms for C6). The mean correlation between head pitch and surround tilt was r = -0.30 for C3 and r = -0.72 for C6. Head pitch also leads visual surround motion (+567 ms for C3 and +539 ms for C6), but with greater variability than sagittal head translation. The results showed that visual stabilization was not consistently achieved during SOT conditions 3 and 6. The fundamental assumption that posture behaves as an inverted pendulum, with control of equilibrium originating in the lower extremities, does not appear to be applicable to the voluntary corrections of sway required during the SOT.

Adult↗
PubMed2000

Development of a novel method for assessing balance: the quantitative posturography system.

Balance is the ability to maintain equilibrium while sitting or standing. There are a number of different methods which are used to assess balance: technical methods such as sway magnetometry, ataxia meter and force platforms, and clinical methods such as the functional reach test, Berg balance test and fall risk index. The most frequently used technical method is the force platform. There are two types of force platform, a static and a dynamic force platform, of which the dynamic force platform has been found to be more sensitive to detect impaired balance. The quantitative posturography system (QPS) described in this paper is a type of dynamic force platform; however, it has a simpler design than the currently available dynamic force platforms and can match the subject's sway exactly for tilting in the anterio-posterior and medio-lateral directions with its novel design. This paper describes the novel design of the QPS and its calibration.

Biomechanical Phenomena↗
PubMed2001

The use of a two-dimensional ultrasound time-of-flight system for location of the centre of gravity in posturography measurements.

A method has been developed for objective assessment of balance using ultrasound time-of-flight (ToF) posturography measurements to accurately locate the centre of gravity (CoG) of a subject. Two orthogonal 40 kHz ultrasound transmitters are mounted on the subject's waist at the height of the CoG. Anterior/posterior and lateral motions are detected independently by measuring variations in the ToF from the transmitters to appropriately positioned wall-mounted receivers. The motion of the CoG is accurately traced during the course of 20 second assessment periods as the subject stands on a solid surface with eyes open and eyes closed. The tests are repeated with the subject standing on a standardized soft surface. Trials of day-to-day repeatability and repeated tests on patients prior to therapy indicate there is no significant improvement to balance measures with experience of the system. Balance measures are significantly worse in patients suffering vertigo symptoms following traumatic brain injury than for equivalent normal volunteers. Repeated measures post-therapy indicate significant improvement in balance measures following vestibular therapy in patients with vertigo. CoG location using ultrasound ToF is a suitable method of tracking sway and thus assessing balance in normals and balance-compromised patients.

Dizziness↗
PubMed1999

Computerized dynamic posturography and seasickness susceptibility.

OBJECTIVE/HYPOTHESIS: The neural mismatch theory emphasizes the role of conflicting multimodal sensory interactions in producing both motion sickness and the rearrangement process that finally leads to habituation to the adverse motion conditions. If this theory is, indeed, correct, the patterns of the response to the integrated signal from simultaneous multisensory stimulation, characterized by unusual relationships between the senses responsible for spatial orientation, should differ according to motion sickness susceptibility. Computerized dynamic posturography (CDP) provides the opportunity to simultaneously change the interactions between visual, somatosensory, and vestibular inputs, thus giving an indication of the relative importance of these senses in maintaining balance. The objective was to investigate balance strategies in naval crew members with differing susceptibility to sea conditions using CDP. STUDY DESIGN: Cross-sectional, parallel-group design. METHODS: Twenty subjects susceptible to seasickness (SS) and 20 nonsusceptible subjects (NSS), healthy male volunteers aged 18 to 25, were tested using the EquiTest system (NeuroCom, Inc., Clackamas, OR). RESULTS: The SS group exhibited significantly less stability than the NSS group in condition 5 of the sensory organization test (SOT). The ratio of the SOT scores of conditions 5 to 1 (the vestibular organization pattern) was also found to be significantly lower in the SS group. CONCLUSIONS: The results suggest that SS might be more dependent on somatosensory and visual inputs and less on vestibular inputs for maintenance of balance compared with NSS. Higher susceptibility to seasickness might reflect abnormal weighting of sensory modalities during the integration process. This would result in disruption of the integration process required to maintain balance and a sense of orientation in space in conditions producing conflicting sensory inputs.

Adolescent↗
PubMed2001

Predicting fall risks in an elderly population: computer dynamic posturography versus electronystagmography test results.

OBJECTIVES/HYPOTHESIS: Falls are the leading cause of morbidity and mortality for persons aged 65 years and older, with more than 2 million people falling and sustaining serious injury annually. This study compared computer dynamic posturography (CDP) and electronystagmography (ENG) results as predictors of falls. STUDY DESIGN: Retrospective. METHODS: Thirty-three patients over the age of 65 years who presented to a balance disorders and falls prevention clinic were used for this study (22 women and 11 men, with an average age of 78.0 y and a mean fall rate of 3.5 times). All had experienced at least one fall in the year before visiting the clinic and were tested with both CDP and ENG. The CDP results were divided into subcategories (sensory organization testing and limits of stability); ENG results were divided into four categories (ocular motor, rotational chair, positional, and caloric studies). RESULTS: Test findings were classified as normal or abnormal based on age-matched normative data. Of the patients in the study, 27.3% were normal for one type of testing and abnormal for the other. Twenty-six patients (78.8%) had abnormal results on CDP, and 20 individuals (60.6%) showed ENG abnormalities (42.4% for ocular motor, 28.6% for positional, 13.6% for caloric, and 11.2% for rotational chair studies). The limits of stability category was significant in predicting multiple falls. CONCLUSION: For this population, CDP was determined to be a more sensitive test for identifying patients who have fallen, with limits of stability testing the most significant part of the CDP battery; for ENG studies, the best falls indicator was the ocular motor battery.

Accidental Falls↗
PubMed2007

Dynamic posturography findings predict balance status in vestibular schwannoma patients.

OBJECTIVE: To test whether condition 5 score (C5S) and condition 6 score (C6S) of the sensory organization test of computerized dynamic platform posturography (CDPP) differ between vestibular schwannoma (VS) patients with and without vestibular symptoms. STUDY DESIGN: Retrospective review of prospectively collected data. SETTING: Tertiary academic referral center. PATIENTS: Two hundred and sixteen consecutive patients with a histological diagnosis of a VS (103 women; 113 men; age range, 18-78 years; median, 54 years) who had been preoperatively evaluated by CDPP. A hundred and twelve patients had a history of vertigo, dizziness, and/or imbalance, and 104 patients had neither present nor past vestibular symptoms at all. INTERVENTION: Diagnostic. Preoperative CDPP in VS patients with and without vestibular symptoms. MAIN OUTCOME MEASURES: Condition 5 score and C6S of the sensory organization test of CDPP of VS patients. To test whether C5S and C6S differ between VS patients with and without vestibular symptoms, the Wilcoxon-Mann-Whitney rank sum test was applied. RESULTS: Both C5S (p = 0.001) and C6S (p < 0.0005) were significantly lower in VS patients with vestibular symptoms than in VS patients without vestibular symptoms. CONCLUSION: There is a significant difference in the distribution of C5S and C6S between VS patients with and without vestibular symptoms. Thus, patients with symptoms tend to have lower C5S and C6S than patients without symptoms, although this trend is not sufficient for reliable discrimination for all patients.

Adolescent↗
PubMed2002

A statistical model for interpreting computerized dynamic posturography data.

Computerized dynamic posturography (CDP) is widely used for assessment of altered balance control. CDP trials are quantified using the equilibrium score (ES), which ranges from zero to 100, as a decreasing function of peak sway angle. The problem of how best to model and analyze ESs from a controlled study is considered. The ES often exhibits a skewed distribution in repeated trials, which can lead to incorrect inference when applying standard regression or analysis of variance models. Furthermore, CDP trials are terminated when a patient loses balance. In these situations, the ES is not observable, but is assigned the lowest possible score--zero. As a result, the response variable has a mixed discrete-continuous distribution, further compromising inference obtained by standard statistical methods. Here, we develop alternative methodology for analyzing ESs under a stochastic model extending the ES to a continuous latent random variable that always exists, but is unobserved in the event of a fall. Loss of balance occurs conditionally, with probability depending on the realized latent ES. After fitting the model by a form of quasi-maximum-likelihood, one may perform statistical inference to assess the effects of explanatory variables. An example is provided, using data from the NIH/NIA Baltimore Longitudinal Study on Aging.

Adult↗
PubMed2006

Evaluating sleepiness using force platform posturography.

We have investigated the feasibility to use posturography as a method to estimate sleep deprivation. This manuscript presents a proof-of-concept of this idea. Twenty-one healthy subjects aged 20-37 years participated in the study. The subjects were deprived of sleep for up to 36 h. Their postural stability was measured as a function of sleep deprivation time. As a reference the critical fusion frequency method for measuring sleepiness was used. The 163 posturographic parameters used for analyzing the posturographic data were found from the literature. Of these parameters, the fractal dimension of the sway path, the most common frequency of the sway, the time-interval for open-loop control of stance, and the most common amplitude of the sway showed the highest linear correlations with sleep deprivation time. Using these four parameters we were able to estimate the sleep deprivation time with an accuracy better than 5 h for 80% of the subjects.

Adult↗