SEARCH · PubMed Health

Results for “Postural control”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

PubMed1980

[Standing ataxia in cerebellar lesions. Differential diagnosis and pathophysiology of disorders of postural control].

Several forms of postural ataxia can be distinguished in cerebellar lesions by quantitative analysis of stance, a paleocerebellar, a vestibulocerebellar and a neocerebellar syndrome, for each of which a different underlying pathomechanism was found. The pathognomonic anterior-posterior 3 Hz postural tremor in the paleocerebellar syndrome is caused by delayed and enhanced long latency reflexes, which result in an oscillation of the posture control system. In the beginning disease this oscillation can be provoked by rapid tilt or electrical stimulation of the tibial nerves. The oscillation frequency correlates inversely with the severity of the disease. In contrast to that, postural ataxia in the vestibulocerebellar syndrome is caused by a loss of intersegmental reflex patterns and a loss of the systems set value. Patients with the neocerebellar syndrome show remarkably less instability. Disturbances are often only provoked by voluntary postural movements as in tracking experiments, which suggests a defect in the interfacing of postural and voluntary motor activity. These cerebellar atactic syndromes may be separated from several forms of postural ataxias of extracerebellar origin.

Cerebellar Ataxia↗

PubMed2006

Time-to-boundary measures of postural control during single leg quiet standing.

A novel approach to quantifying postural stability in single leg stance is assessment of time-to-boundary (TTB) of center of pressure (COP) excursions. TTB measures estimate the time required for the COP to reach the boundary of the base of support if it were to continue on its instantaneous trajectory and velocity, thus quantifying the spatiotemporal characteristics of postural control. Our purposes were to examine: (a) the intrasession reliability of TTB and traditional COP-based measures of postural control, and (b) the correlations between these measures. Twenty-four young women completed three 10-second trials of single-limb quiet standing on each limb. Traditional measures included mean velocity, standard deviation, and range of mediolateral (ML) and anterior-posterior (AP) COP excursions. TTB variables were the absolute minimum, mean of minimum samples, and standard deviation of minimum samples in the ML and AP directions. The intrasession reliability of TTB measures was comparable to traditional COP based measures. Correlations between TTB and traditional COP based measures were weaker than those within each category of measures, indicating that TTB measures capture different aspects of postural control than traditional measures. TTB measures provide a unique method of assessing spatiotemporal characteristics of postural control during single limb stance.

Adult↗

PubMed1985

[Computerized analysis of the effects of age on posture control].

The authors examined postural sway in 112 normal subjects by means of a computerized force platform system. The performances of 14 subjects (7 males and 7 females) for each of these age groups: 12-15, 16-19 and the six next decades until 79 years were considered. The posturographic test requires two trials, one with eyes open and another with eyes closed, with patients in Romberg's position. On the average eyes-closed measurements have always been greater than those with eyes open. Moreover this study shows that during the growth the characteristics of postural control are different between the two sexes and as regards adult performances. During ageing a progressive significant stability impairment, especially upon visual deprivation, was shown.

Adolescent↗

PubMedDate not supplied

Age-related changes in human posture control: sensory organization tests.

Postural control was measured in 214 human subjects ranging in age from 7 to 81 y. Sensory organization tests measured the magnitude of anterior-posterior body sway during six 21 s trials in which visual and somatosensory orientation cues were normal, altered (by rotating the visual surround and support surface in proportion to the subject's sway), or vision eliminated (eyes closed). No age-related increase in postural sway was found for subjects standing on a fixed support surface with eyes open or closed. However, age- related increases in sway were found for conditions involving altered visual or somatosensory cues. Subjects older than about 55 y showed the largest sway increases. Subjects younger than about 15 y were also sensitive to alteration of sensory cues. On average, the older subjects were more affected by altered visual cues, whereas younger subjects had more difficulty with altered somatosensory cues.

Adolescent↗

PubMed1990

Posturography following rotation: a model of posture control during vestibular dysfunction.

Postural stability is influenced by multiple sensory inputs, including visual, somatosensory, and vestibular cues. Adaptive changes in how these sensory inputs influence posture may occur in the presence of vestibular dysfunction. In this study, we simulated vestibular dysfunction in normal subjects in order to study immediate and adaptive modifications in postural control under reproducible and reversible experimental conditions. Twenty subjects (ages 20 to 35 years) were tested on a force-detecting platform; the support surface or visual surround was modulated (anterior-posterior) proportionally to body sway. Vestibular dysfunction was simulated by rotating subjects with their eyes closed at 180 degrees/second for 30 seconds, then rapidly halting rotation. Posturographic measures were obtained during the subsequent 20 seconds. Ten identical rotation trials for each subject were performed, alternating the direction of rotation, and with either the support surface or the visual surround modulated with sway in different subjects. Thus, only one sensory modality could provide Earth-stable sensory cues. Control groups were tested to assess effects of repeated alternating rotations alone, and effects of repeated posturographic trials alone. Sway was quantified by measuring peak-to-peak excursions of the center of mass. Results showed that subjects were more stable after rotation when they were provided with a stable support surface than with a stable visual surround. No subject could maintain stance without at least one Earth-stable sensory input. Improvement of mean sway scores in either group was not significant, although isolated cases did exhibit adaptive changes with improved stability over repeated trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2000

Methods for evaluation of postural control adaptation.

New methods were developed to determine the dynamic changes of postural control during the initial exposure to large perturbances of stance. The adjustments of postural control over time in measured anteroposterior torque, were investigated in ten normal subjects. Perturbations of stance were evoked by two high intensity vibrators applying pseudorandom stimulation either to the calf muscles or the paravertebral muscles of the neck. The new methods use a system identification approach, which distinguishes between feedback control, adaptation of postural responses and adaptation to stimulus. This approach makes it possible to quantify motion dynamics and complexity, stimulus impact and adjustments of postural control. Quantification of the different adaptive responses could be useful for diagnostic purposes, in evaluating treatment efficacy and patient progress in rehabilitation programs.

Adaptation, Physiological↗

PubMed1991

Postural control in blinds and in Usher's syndrome.

The postural control mechanisms were evaluated in 10 blinds and in 10 subjects with Usher's syndrome. The results were compared with 27 age matched healthy volunteers. In visual conditions the subjects with Usher's syndrome performed worse, but in nonvisual condition they performed equally well as the controls. The results were the same irrespective of whether the tests were performed on a rigid surface or foam rubber covered surface. The blinds and controls performed equally well on the bare surface, but the blinds performed significantly better on the foam rubber covered surface. The results indicate that in subjects with Usher's syndrome the vestibulo-cochlear degeneration is well compensated but the postural stability aggravated due to retinal degeneration. Blind subjects have a better postural control than their seeing referents, but the difference is only evident in situations in which the postural control is hampered by surface perturbation.

Adolescent↗

PubMedDate not supplied

Developmental perspective of sensory organization on postural control.

The development of sensory organization on postural control was studied using computerized dynamic posturography. Generalized postural stability increased with age but had not reached the adult level at the age of 15 years. The significance of each sensory component for postural control was analysed. Somatosensory function developed early and became comparable with the adult level at the age of 3-4 years. The visual function followed and reached the adult level at the age of 15 years. The vestibular function developed later, showing a considerably lower level even at the age of 15 years. Girls were superior to boys with respect to the vestibular function at the age of 7-8 years. The implication of this sexual difference for some developmental disorders is discussed.

Adolescent↗

PubMed2005

Postural control after vestibular schwannoma resection measured with visual feedback posturography.

BACKGROUND: Vestibular symptoms after surgery diminish rapidly, but the simultaneous progress in active postural control has not been fully addressed. OBJECTIVES: The aim was to evaluate the progress in postural control in operated vestibular schwannoma (VS) patients with visual feedback posturography (VFP). METHODS: 36 consecutive patients with unilateral VS were studied with the VFP pre-operatively, 1 month and 3 months after the surgery. The accuracy and velocity of active postural control movements to distant targets in VFP was measured and compared to that of healthy controls. RESULTS: The hold percentage within the targets was significantly reduced in the VS patients compared to the controls (pre-operatively p = 0.005; postoperatively at 1 month p = 0.002 and at 3 months p = 0.017). The sway velocity (SV) within the targets among patients with VS was significantly increased pre-operatively (p = 0.009), at the 1-month (p = 0.004) and at the 3-month follow-up visits (p = 0.016). All the postural control parameters except SV tended to improve slightly postoperatively. The consecutive VFP measurements in individual VS patients correlated statistically significantly (p < 0.001 for all parameters). The abnormality in the pre-operative VFP results correlated statistically significantly with that of postoperative VFP (p = 0.001). CONCLUSIONS: The VFP is an objective and repeatable method, which can be used to assess and follow up the active postural control in individual patients with VS. Persisting abnormality in the VFP seems to be an indication for more aggressive vestibular rehabilitation to normalize the disturbed postural control.

Adult↗

PubMed2002

Postural control and venous gas bubble formation during hypobaric exposure.

BACKGROUND: Earlier studies have shown that acute hypoxia at simulated altitudes up to 18,000 ft affects postural control. The main objective of this study was to investigate whether this is caused by hypoxia or by other effects of reduced barometric pressure. Doppler monitoring was included to rule out venous gas emboli (VGE) as a possible cause of disturbed postural control. A secondary objective was to evaluate two conventional altitude chamber training profiles regarding release of VGE. HYPOTHESIS: Chamber flights up to 18,000 ft affect postural control due to acute hypoxia or other effects of reduced barometric pressure such as bubble formation. VGE probably will not be formed at the altitude chamber flight profiles and procedures selected for this study. METHODS: Repeated registrations of postural control and Doppler monitoring for detection of possible VGE were performed on 12 subjects before, during, and after exposure to two different altitude chamber flight profiles. In chamber flight profile 1 the subjects were first preoxygenated for 45 min and then exposed to a normoxic environment at altitudes of 25,000, 18,000, 14,000, and 8000 ft. Chamber flight profile 2 consisted of an 80 min exposure to 14,000 ft without preoxygenation or supplemental oxygen for the first 60 min. RESULTS: In chamber flight profile 1, where normoxic conditions were achieved during all balance testing, no significant changes in postural control were found. No VGE were observed and no subjective dizziness was reported during this exposure. In chamber flight profile 2, a significant influence on postural control was reported for the eyes-open condition, when breathing air at 14,000 ft. These changes normalized when reaching ground level. VGE were observed in one of the 12 subjects after 75 min at 14,000 ft. Another subject complained of severe dizziness during the initial part of the decompression to 14,000 ft, and was excluded from further experiments. CONCLUSIONS: Changes in postural control at altitudes up to 18,000 ft is probably due to acute hypoxia. VGE may form during acute altitude exposure to 14,000 ft.

Adult↗

PubMed1989

Effects of unilateral loss of vestibular function on the vestibulo-ocular reflex and postural control.

Long-term recovery from surgically induced unilateral loss of vestibular function was studied in 14 patients. Seven patients underwent surgical extirpation or section of the vestibular nerve, and seven patients underwent labyrinthectomy without vestibular nerve section. The vestibulo-ocular reflex (VOR) and postural control were evaluated preoperatively and monitored for up to 4 years postoperatively with use of pseudorandom rotation (combined sinusoidal frequencies from 0.009 to 1.5 Hz) and moving platform posturography. Immediately following surgery all patients showed minimal reductions in the VOR gain constant, but marked reduction in the time constant, and marked increase in slow eye velocity bias. Bias returned to normal values within about 10 days, but time constants never returned to normal values. Results of standard Romberg tests in these patients were normal throughout the preoperative and postoperative periods. However, all patients showed marked postural control abnormalities in tests of the ability to maintain balance in unusual sensory environments in the immediate postoperative period. Seventy-five percent of the patients eventually recovered normal postural control. Postural control returned to near baseline performance with a time course similar to that of the VOR bias. However, postural control also continued to improve after the recovery of VOR bias was complete.

Adolescent↗

PubMed1995

The effect of environmental regulations on postural control after stroke.

OBJECTIVES: The primary objective of this study was to examine the effect of environmental predictability on postural control after stroke. A reaching task for seated subjects was used as the postural perturbation. Trajectory stability (the pathway followed by the subject's body center for pressure with respect to time during the reaching task) was used as the index of postural control. It was hypothesized that trajectory stability would be greater under predictable conditions. METHOD: A specially designed electromechanical system was used to measure the trajectory stability ratios for 100 subjects, 50 with poststroke hemiplegia and 50 who had not had stroke. All subjects completed a task that required reaching to the left versus reaching to the right, under predictable versus unpredictable conditions. Postural control was measured via a trajectory instability ratio in both the anterior-posterior and medial-lateral planes. RESULTS: Although the effect of predictability on postural control was significant, it was not as hypothesized for both groups. There was greater trajectory stability under unpredictable conditions when reaching to the right as measured in both the anterior-posterior and medial-lateral planes and when reaching to the left as measured in the medial-lateral plane. CONCLUSION: These findings refute the assumption of the hierarchical, predictable-to-unpredictable-environment model for postural control evaluation and treatment. The relationship between information processing demands and postural skill is probably more complex than the simple linear association implied. Perhaps the two conditions, predictable and unpredictable, should be worked on concurrently, not sequentially.

Adult↗

PubMed1994

The differential effects of external ankle support on postural control.

Ankle supports are commonly used in an attempt to decrease the risk of ankle injury during sport. However, their use may also impair postural control, which is an integral component of sports participation. The aim of this study was to investigate the effects of three different ankle supports (tape, brace, and elastic bandage) on postural control in 24 normal subjects with a mean age of 24.8 years (+/- 4.4). Two measures were used to evaluate postural control in one-legged stance with the eyes closed: variability of mediolateral ground reaction force (acquired from a force platform) and frequency of foot touchdowns by the nonsupport leg (assumed to indicate ability of the subject to maintain one-legged stance posture). Both measures revealed a differential effect for ankle support on postural control. The use of an elastic bandage had no significant effect on postural control (p > 0.05), while the use of tape or a brace had a significant detrimental effect (p < 0.05). While wearing the tape or a brace, subjects were less steady and touched down more frequently. Restriction of ankle movement was offered as a possible explanation for the results, since postural control was impaired only by the ankle supports which limited ankle motion. These findings may have implications regarding impaired athletic performance.

Adult↗

PubMed2001

Knee bracing after ACL reconstruction: effects on postural control and proprioception.

PURPOSE: To evaluate the effects an anterior cruciate ligament (ACL) brace has on various measures of knee proprioception and postural control. METHODS: Thirty subjects (mean age 27 +/- 11 yr) having undergone unilateral ACL reconstruction were tested with and without wearing their own custom-fit brace on their involved limb. Proprioception was assessed using joint angle replication tests completed on an isokinetic dynamometer. Postural control was assessed using a series of single-limb standing balance tests completed on a force platform. The balance tests included: 1) standing on the stable platform with eyes open, 2) standing on a foam mat placed over the platform with eyes open, 3) standing on the platform with eyes closed, and 4) standing on the platform after landing from a maximal single-limb forward hop. RESULTS: The brace provided a small but statistically significant improvement in proprioception (mean reduction in error scores between target and reproduced angles = 0.64 +/- 1.4 degrees, P = 0.02). For the postural control tests, there was a significant brace condition by test situation interaction (P = 0.02), with the brace providing a small but statistically significant improvement during the test completed on the stable platform with eyes open (mean reduction in center of pressure path length = 4.2 +/- 8.4 cm, P = 0.02) but not during the other more challenging test situations. Additional post hoc analyses indicated that the relationship between knee proprioception and postural control measures were low and not significant (r = 0.003 to 0.19, P > 0.32), consistent with the suggestion that changes in knee proprioception can occur in the absence of substantial changes in postural control. Also, standing balance tests that challenged the somatosensory contribution to postural control (i.e., those completed on foam, or with eyes closed) were significantly related to single-limb forward hop distances (r = -0.4, P < 0.05), whereas performance during the proprioception test was not (r = 0.1, P > 0.50). CONCLUSIONS: In general, bracing appears to improve performance during tasks characterized by relatively limited somatosensory input but not during tasks characterized by increased somatosenory input. The small magnitude of the improvements, coupled with their apparent lack of carry over to more difficult and functionally relevant tasks, questions the clinical benefit of the present effects of bracing.

Adult↗

PubMed1994

Sensory stimulation promotes normalization of postural control after stroke.

BACKGROUND AND PURPOSE: In a randomized study of hemiparetic stroke patients with a median age of 75 years, functional recovery was significantly better in those who received additional sensory stimulation (n = 38), including electrostimulation, than in control patients (n = 40) given the same physiotherapy and occupational therapy; group differences for balance, mobility, and activities of daily living were significant. The present study was designed to investigate postural control in patients who survived more than 2 years after stroke onset. METHODS: The 48 survivors (mean, 2.7 years; range, 2.0 to 3.8 years), 22 from the treatment group and 26 from the control group, were compared with 23 age-matched healthy subjects. Subjects were perturbed by vibrators applied to calf muscles or with galvanic vestibular stimulation. We evaluated postural control in terms of sway variances or sway velocities and the dynamics of postural control as a feedback system using system identification with a model previously validated for human postural control. RESULTS: Significantly more patients of the treatment group than of the control group maintained stance during perturbations (P < .01). Among patients capable of maintaining stance during perturbation, the control patients were characterized by significant divergence from normal values in two of the three characteristic parameters of dynamic postural control (ie, swiftness and stiffness; P < .05) compared with the treatment subgroup or age-matched subjects. CONCLUSIONS: The course of sensory stimulation enhanced recovery of postural function, an enhancement still significant 2 years after the lesion and treatment. The differences and near normalization of characteristic parameters of dynamic postural control among treated patients suggest that improved recovery after sensory stimulation may be achieved by patients regaining normal or near normal dynamics of human postural control.

Activities of Daily Living↗

PubMed1998

Unilateral postural control of the functionally dominant and nondominant extremities of healthy subjects.

OBJECTIVE: To determine whether a difference in unilateral postural stability exists between the functionally dominant and nondominant legs of a healthy population. DESIGN AND SETTING: The unilateral postural control of both legs of healthy subjects was tested using a force plafform. Before the postural control examination, each subject performed a series of functional tests to determine functional leg dominance. SUBJECTS: Ten healthy young adults with a mean age of 19.2 +/- 3.2 years volunteered for this study. MEASUREMENTS: Functional leg dominance was determined through the use of a battery of tests that included 3 separate evaluations of lower extremity dominance for functional activity. Two measures of postural control, sway area (SA) and sway path length (SPL), were collected for both the dominant and nondominant legs of all subjects. An analysis of variance (ANOVA) was used to determine whether a difference in postural control between the 2 legs was present. RESULTS: A subject x leg repeated-measures ANOVA was conducted on both dependent variables, SA and SPL. The SA ANOVA value was not significant. The mean value for the dominant-leg SA measurement was 9737.43 +/- 303.36 mm(2), whereas the mean SA for the nondominant leg was 9431.74 +/- 349.97 mm(2). The SPL ANOVA also showed no significant difference in the bilateral comparison. The mean SPL for the dominant leg was 4321.57 +/- 630.0 mm, and the mean SPL for the nondominant leg was 4341.88 +/- 1,013.31 mm. CONCLUSIONS: We found no difference in unilateral postural stability between the functionally dominant and nondominant lower limbs in a healthy population of young adults. This is of particular interest to the clinician who commonly uses singleleg postural control evaluations in the assessment of an athlete's level of progress in the rehabilitation setting.

Journal Article↗

PubMed2006

Postural control after a night without sleep.

The present study analysed the efficiency of postural control after 12 h of nocturnal forced wakefulness using Romberg's test comprising 1 min of recording with eyes-open and 1 min of recording with eyes-closed, with a 1 min break between the two sessions. Our aim was to see if the decreased postural control efficiency after a sleepless night was unspecific (in both eyes-closed and eyes-open conditions) or selective (in only one of the conditions). A total of 55 students spent a whole night awake at our laboratory and were tested at 22:00 and 08:00 h. In general, the results showed that postural sway increased, performing the recording from eyes-open to eyes-closed condition. The statokinesigram length (SL or efficiency of the postural system) increased after the sleepless night, while in eyes-open condition, the length in function of surface (LFS or accuracy of postural control) and Romberg's index (or contribution of vision to maintain posture) significantly decreased. This could indicate that after a night without sleep, there is a slower elaboration of visual inputs in the postural control process. On the basis of these results, the effects of sleep deprivation on cognitive performance were considered from a neuropsychological point of view.

Adult↗

PubMed2006

Biomechanical capabilities influence postural control strategies in the cat hindlimb.

During postural responses to perturbations, horizontal plane forces generated by the cat hindlimb are stereotypically directed either towards or away from the animal's center of mass, independent of perturbation direction. We used a static, three-dimensional musculoskeletal model of the hindlimb to investigate possible biomechanical determinants of this "force constraint strategy." We hypothesized that directions in which the hindlimb can produce large forces are preferentially used in postural control. We computed feasible force sets (FFSs) based on hindlimb configurations of three cats during postural equilibrium tasks and compared them to horizontal plane postural force directions. The grand mean FFS was bimodal, with maxima near the posterior-anterior axis (-86+/-8 degrees and 71+/-4 degrees ), and minima near the medial-lateral axis (177+/-8 degrees and 8+/-8 degrees ). Experimental postural force directions clustered near both maxima; there were no medial postural forces near the absolute minimum. However, the medians of the anterior and posterior postural force direction histograms in the right hindlimb were rotated counter-clockwise from the FFS maxima (p<0.05; Wilcoxon signed-rank test). Because the posterior-anterior alignment of the FFS is consistent with a hindlimb structure optimized for locomotion, we conclude that the biomechanical capabilities of the hindlimb strongly influence, but do not uniquely determine the force directions observed in the force constraint strategy. Forces used in postural control may reflect a balance between a neural preference for using forces in the directions of large feasible forces and other criteria, such as the stabilization of the center of mass, and muscular coordination strategies.

Animals↗