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 1,279 records · Page 71Linked to original sources

PubMed2004

Detecting postural responses to sinusoidal sensory inputs: a statistical approach.

A common way for understanding sensory integration in postural control is to provide sinusoidal perturbations to the sensory systems involved in balance. However, not all subjects exhibit a response to the perturbation. Determining whether or not a response has occurred is usually done qualitatively, e.g., by visual inspection of the power spectrum. In this paper, we present the application of a statistical test for quantifying whether or not a postural sway response is present. The test uses an F-statistic for determining if there is significant power in postural sway data at the stimulus frequency. In order to describe the application of this method, 20 subjects viewed sinusoidal anterior-posterior (A-P) optic flow at 0.1 and 0.25 Hz, while their A-P head translation was measured. The test showed that significant postural responses were detected at the stimulus frequency in 12/20 subjects at 0.1 Hz and 13/20 subjects at 0.25 Hz.

Adult↗

PubMed1977

Falls in the elderly related to postural imbalance.

Two hundred and forty-three elderly people aged 60 to 96 years were questioned about their falls, and their sway was measured. For comparison sway was also measured in 63 younger subjects. Sway increased with age and was higher in women at all ages. There was no difference in sway between those with no history of falls and those who fell only because of tripping. In both sexes sway was significantly increases in people who fell because of loss of balance and in women whose falls were due to giddiness, drop attacks, turning the head, and rising from bed or a chair. This suggests that there is a physiological decline in postural control with advancing age and also a decline due to disease of the central nervous system.

Accidents, Home↗

PubMed2002

Subacute systemic 3-nitropropionic acid intoxication induces a distinct motor disorder in adult C57Bl/6 mice: behavioural and histopathological characterisation.

Data on motor behavioural disorders induced by systemic 3-nitropropionic acid, an irreversible inhibitor of mitochondrial succinate dehydrogenase and their histopathological correlates in mice, are sparse. We thus further characterised the subacute 3-nitropropionic-acid-induced motor disorder and its time course in C57Bl/6 mice using standard behavioural tests, histopathological correlates and in vivo magnetic resonance imaging. Firstly, we studied two intoxication paradigms (340 and 560 mg 3-nitropropionic acid/kg, 7 days) compared to controls. The low-dose regimen induced only slight motor changes (reduced hindlimb stride length and rearing). The high-dose regimen induced significant (P<0.05) behavioural and sensorimotor integration deficits (pole test, rotarod, stride length, open-field spontaneous activity) but with 37.5% lethality at week one. The clinical motor disorder consisted of hindlimb clasping and dystonia, truncal dystonia, bradykinesia and impaired postural control. Histopathologically, there were discrete lesions of the dorsolateral striatum in 62.5% of mice together with a 32% reduction (P<0.0001) of the striatal volume, reduced caldbindin-D28K immunoreactivity in the lateral striatum, and met-enkephalin and substance P in the striatal output pathways. There was also a significant (P<0.05) 30-40% dopaminergic cell loss within the substantia nigra pars compacta. Secondly, we validated a semi-quantitative behavioural scale to describe the time course of the motor deficits and to predict the occurrence of striatal damage. We sought to determine whether it could also be disclosed in vivo by magnetic resonance imaging. The scale correlated with the striatal volume reduction (r(2)=0.57) and striatal cell loss (r(2)=0.87) but not with the loss of striatal dopaminergic terminals (dopamine transporter binding). Increased T2-signal intensity within the striatal lesion correlated with the cell loss (r(2)=0.66). We conclude that systemic administration of 3-nitropropionic acid in C57Bl/6 mice induces a distinct motor disorder and dose-dependent striatonigral damage, which are potentially useful to model human diseases of the basal ganglia.

Age Factors↗

PubMed2000

Body positions used by healthy and frail older adults to rise from the floor.

OBJECTIVE: The purpose of this study was to describe how older adults, particularly more physically impaired older adults, might differ from healthy controls in the body positions used to rise from the floor. DESIGN: Cross-sectional analysis of young, healthy older, and congregate housing older women. SETTING: University-based laboratory and congregate housing facility. PARTICIPANTS: Healthy young university student controls (n = 22, mean age 23 years); healthy old adults living independently in the community (n = 24, mean age 73 years); and congregate housing older adults (n = 29, mean age 81 years). INTERVENTION: Videotaping and timing of rising from a supine position on the floor to standing. MAIN OUTCOME MEASURES: In addition to the time taken to rise from the floor, 10 specific trunk and extremity positions used during the rise, termed Intermediate Positions (IP), were identified. RESULTS: The Young controls had the fastest rise time and used the fewest number of IP, whereas the Congregate residents had the slowest rise time and used the most IP, with the Healthy old adults intermediate in both time and IP use. Prevalence of certain IP, together with correlational and factor analyses, suggest that use of Sit and Crouch was the most preferred rise strategy for the Young controls, whereas use of Tuck, Crouch-Kneel, All Fours, and Bearwalk was the most preferred rise strategy among the Congregate residents. The Healthy old used IP common to both Young and Congregate residents, reflecting a rise strategy intermediate to the latter groups. A substantial subset of the Congregate residents (38%) were unable to rise without assistance and appeared to use certain preparatory positions (Sit, Kneel, Tuck) but were unable to get into presumably more challenging positions (Crouch-Kneel, All Fours, Bearwalk). CONCLUSIONS: With increasing age and physical impairment, body positions used during rising from the floor suggest a preference for maintaining upper and lower extremity contact with the floor, presumably minimizing the lower extremity strength requirements to rise and maximizing stability and postural control. These intermediate body positions may be useful as the basis for training older adults to rise from the floor.

Activities of Daily Living↗

PubMed1996

Training affects the development of postural adjustments in sitting infants.

1. The present study addressed the question of whether daily balance training can affect the development of postural adjustments in sitting infants. 2. Postural responses during sitting on a moveable platform were assessed in twenty healthy infants at 5-6, 7-8 and 9-10 months of age. Multiple surface EMGs and kinematics were recorded while the infants were exposed to slow and fast horizontal forward (Fw) and backward (Bw) displacements of the platform. After the first session the parents of nine infants trained their child's sitting balance daily. 3. At the youngest age, when none of the infants could sit independently, the muscle activation patterns were direction specific and showed a large variation. This variation decreased with increasing age, resulting in selection of the most complete responses. Training facilitated response selection both during Fw and Bw translations. This suggests a training effect on the first level of the central pattern generator (CPG) model of postural control. 4. Training also affected the development of response modulation during Fw translations. It accelerated the development of: (1) the ability to modulate EMG amplitude with respect to platform velocity and initial sitting position, (2) antagonist activity and (3) a distal onset of the response. These findings point to a training effect on the second level of the CPG model of postural adjustments.

Age Factors↗

PubMed1989

Determination of characteristic parameters of human postural dynamics.

Posture control performance was quantified in three variables (swiftness, stiffness, damping). Subjects were tested with a force platform recording body sway induced by vibrators attached to the calf muscles. Parameter estimation was made with identification of a transfer function representing the stabilized inverted pendulum. It is conjectured that the state feedback parameters identified are suitable for use in assessing ability to maintain posture.

Adult↗

PubMed1988

Medullary regions mediating atonia.

Electrical stimulation studies have implicated the medial medulla in the inhibition of muscle tone. In the present report we present evidence for suppression of muscle tone by chemical activation of the medial medulla. We find 2 distinct zones within the classically defined medial medullary inhibitory area. A rostral region corresponding to the nucleus magnocellularis (NMC) is sensitive to glutamate. Atonia produced by activation of this region is mediated by non-NMDA receptors. A caudal region, corresponding to the nucleus paramedianus (NPM) is sensitive to ACh. Atonia produced by activation of this region is mediated by muscarinic receptors. Activation of these regions both in acute decerebrate and intact cats suppresses muscle tone. We find that the cholinoceptive dorsolateral pontine region, previously implicated in atonia control, can be activated by glutamate-sensitive non-NMDA receptors. Microinjection of atropine into the NPM or of glutamylglycine into the NMC blocks atonia elicited by pontine carbachol injection. The medullary regions identified here are hypothesized to mediate the suppression of muscle tone that occurs in rapid eye movement sleep and in cataplexy and may have a role in postural control in waking.

Acetylcholine↗

PubMed1996

Auditory feedback regulation of perturbed stance in stroke patients.

The effect of auditory input on impaired postural control perturbations was evaluated in two groups of stroke patients participating in a rehabilitation programme after a recent (< 12 months) and single episode of stroke, or less recent (> 12 months), and multiple episodes of stroke. Auditory input took the form of feedback signals generated by the forces actuated by the feet on a force platform in response to the patient's postural movements. Vibratory stimuli applied to the calf muscles induced sudden perturbations which the patients had to counteract to maintain an upright stance. The effect of auditory feedback in facilitating the maintenance of stance was measured in terms of sagittal torque variance (body sway) recorded on a force platform. In the presence of auditory feedback, body torque variance in response to perturbed posture was significantly reduced in the recent stroke group, whereas in the less recent stroke group the auditory feedback did not prove effective. Moreover, learning seems essential to utilize the auditory feedback.

Acoustic Stimulation↗

PubMed2004

Brain activation patterns during imagined stance and locomotion in functional magnetic resonance imaging.

Posture and gait are sensorimotor actions that involve peripheral, spinal, and supraspinal structures. To investigate brain activity during stance and locomotion, 13 healthy subjects were asked to stand, walk, run, and lie down; subsequently, they were trained to imagine standing, walking, running, and lying [imagined lying as rest condition in functional magnetic resonance imaging (fMRI)]. Separate and distinct activation/deactivation patterns were found for the three imagined conditions: (1) standing imagery was associated with activation in the thalamus, basal ganglia, and cerebellar vermis; (2) walking imagery was associated with activation in the parahippocampal and fusiform gyri (areas involved in visuospatial navigation), occipital visual areas, and in the cerebellum; (3) running imagery caused a predominantly cerebellar activation in the vermis and adjacent hemispheres (six times larger than during imagination of walking or standing), but activations in the parahippocampal and fusiform gyri were smaller than during walking. Deactivations were found for walking and running, but not for standing imagery. They were located in the vestibular (posterior insula, superior temporal gyrus, supramarginal gyrus) and somatosensory (postcentral gyrus) cortex with right-hemispheric dominance. These findings support the concept of a hierarchical organization of posture and locomotion. Automated locomotion, for example, running, is based on spinal generators whose pace is driven by the cerebellar locomotor region. Deactivation in the vestibular and somatosensory cortex prevents adverse interactions with the optimized spinal pattern and sensory signals; this confirms earlier findings of a multisensory inhibition during unhindered locomotion. During slow walking, spatial navigation, mediated by the parahippocampal cortex, becomes more important. Postural control during standing involves a low intensity cerebellar activity and sensorimotor control via the thalamus and basal ganglia.

Adult↗

PubMed2001

The soleus late response elicited by transcranial magnetic stimulation reflects agonist-antagonist postural adjustment in the lower limbs.

OBJECTIVES: We studied the origin and underlying mechanism of the soleus late response (SLR) at a mean latency of 90 ms following transcranial magnetic stimulation. METHODS: The soleus primary response (SPR) and SLR were recorded from the soleus (SOL) muscle in 27 normal subjects under various conditions using a double-cone coil. We also tested 28 patients demonstrating neurological disorders with postural disturbance. RESULTS: The amplitude of the SPR gradually increased and its latency gradually decreased against the voluntary contraction (0-80%) of the tibialis anterior (TA) muscle. In contrast, the SLR amplitude was the greatest at a 20% TA contraction while the SLR latency was the shortest at a 40% TA contraction. The preactivation of SOL enhanced the SPR response but did not evoke the SLR. The SPR amplitude was significantly augmented while standing, however, the SLR amplitude tended to decrease. The SLR was never obtained following the stimulation of the brainstem, lumbar roots and peroneal nerve. The SLR was abnormal in patients with cerebellar ataxia and Parkinson's disease while the SPR was normal. CONCLUSIONS: A lack of any correlation between the SPR and SLR suggests that the SLR does not originate in the corticospinal tract. The SLR may thus be a polysynaptic response related to the postural control of the agonist and antagonist organization between the TA and SOL.

Adult↗

PubMed2006

Driving with distraction in Parkinson disease.

OBJECTIVE: To assess the effects of auditory-verbal distraction on driving performance in Parkinson disease (PD). METHODS: We tested licensed, currently active drivers with mild-to-moderate PD (n = 71) and elderly controls with no neurologic disease (n = 147) on a battery of cognitive, visual, and motor tests. While they drove on a four-lane interstate freeway in an instrumented vehicle, we determined at-fault safety errors and vehicle control measures during a distracter task (Paced Auditory Serial Addition Task [PASAT]) and on an uneventful baseline segment. RESULTS: Compared with controls, drivers with PD committed more errors during both baseline and distraction, and drove slower with higher speed variability during distraction. Although the average effect of distraction on driving performance compared with baseline was not different between the groups, the drivers with PD showed a more heterogeneous response to distraction (p < 0.001): the error count increased in 28.2% of drivers with PD (vs 15.8% in controls), decreased in 16.9% (vs 3.4%), and remained stable in 54.9% (vs 80.8%). The odds of increase in safety errors due to distraction was higher in the PD group even after adjusting for baseline errors, level of engagement in PASAT, sex, and education (odds ratio [95% CI] = 2.62 [1.19 to 5.74], p = 0.016). Decreased performance on tests of cognitive flexibility, verbal memory, postural control, and increased daytime sleepiness predicted worsening of driving performance due to distraction within the PD group. CONCLUSION: The quantitative effect of an auditory-verbal distracter task on driving performance was not significantly different between Parkinson disease (PD) and control groups. However, a significantly larger subset of drivers with PD had worsening of their driving safety errors during distraction. Measures of cognition, motor function, and sleepiness predicted effects of distraction on driving performance within the PD group.

Accidents, Traffic↗

PubMed2003

An investigation of stability limits while holding a load.

The objective of this study was to investigate the effects of load height and foot placement on the functional base of support (FBOS) limits and the postures that participants used when they reached their FBOS limits. Twelve young male participants were tested while holding a 12-kg load at reach (above their heads), at shoulder and knuckle height, and unladen under both wide and narrow foot placements. The FBOS limits and the centre of pressure (COP) excursion length were calculated based on data from a force platform. Postural angles when participants reached their FBOS limits were calculated from records of a 2-D motion analysis system. The results showed that the load height had greater effect on the posterior FBOS limit. As the load height decreased, the COP excursion length decreased. Participants were prone to using a hip strategy to maintain postural balance when reaching their FBOS limits. Quantitative data of FBOS limits and postural control while participants hold a load at various heights when reaching their FBOS limits is of value for designing a safe materials handling workplace.

Adolescent↗

PubMed2003

[A comparative study of the perceptual and motor performance at school age of preterm and full term children].

The objective of this study was to compare the perceptualmotor performance in school age children who were born preterm and full term. Two groups of children, ages 5 to 7, participated in this study. Group I had 35 children, from low-income families, born up to the 34 week of gestation and/or weight bellow 1500 g. Group II had 35 full-term children, matched by age, gender and socioeconomic status to the children in Group I. Children were tested on the Bender gestalt, the motor accuracy test and on balance and postural responses measures. The preterm group obtained significantly lower scores in the majority of the tests. These besides reinforcing the importance of the follow-up of preterm children up to school age, also indicate the need to stimulate the fine motor and postural control Devment, even among preterm children who do not show evidence of neurological impairment.

Child↗

PubMed2005

Canalith repositioning for benign paroxysmal positional vertigo.

OBJECTIVE: To evaluate the efficacy of canalith repositioning maneuvers (Semont, Epley, and modified maneuvers) in the treatment of posterior canal benign paroxysmal positional vertigo (BPPV) in comparison to the rate of resolution in the untreated control cohort. DATA SOURCES: Source articles were identified by a MEDLINE search of English language sources before 2004 plus manual crosschecks of bibliographies from identified articles, selected national meeting abstracts, review article references, and textbook chapters. STUDY SELECTION: Each controlled trial that compared canalith repositioning patients to untreated control subjects in posterior canal benign positional vertigo (blinded and unblinded) was reviewed for inclusion. DATA EXTRACTION: Data were abstracted systematically, scaled on validity and comparability, and cross-checked independently by another author. DATA SYNTHESIS: Studies were combined with fixed effects meta-analysis to estimate spontaneous resolution, 95% confidence intervals (CI) of effect size, and heterogeneity. CONCLUSION: Canalith repositioning is more effective than observation alone for the treatment of benign paroxysmal positional vertigo, despite spontaneous resolution rates of one in three at 3 weeks. Public health implications are discussed, based on the high frequency of unrecognized BPPV reported in elderly patients, and the improvements after canalith repositioning in postural control and health-related quality of life (SF 36 Health Survey) documented in the literature.

Humans↗

PubMed2005

Gait initiation and dynamic balance control in Parkinson's disease.

OBJECTIVE: To determine whether the magnitude of the separation between the center of pressure (COP) and the whole-body center of mass (COM) during gait initiation can differentiate patients with varying severity of Parkinson's disease (PD) disability. DESIGN: Cross-sectional, intact groups research design. SETTING: Biomechanics research laboratory. PARTICIPANTS: Forty-three patients were stratified into 2 groups based on the Hoehn and Yahr (H&Y) disability score, which heavily favors balance in determining disability. The 2 groups were: H&Y score of 2.0 or less (n=23; age, 61+/-10y) or H&Y score of 2.5 or higher (n=20; age, 70+/-9y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The peak COP-COM distance represents the maximum separation between the location of the whole-body COM and the ground reaction force's COP, and thus is an indicator of dynamic balance control. The peak COP-COM was evaluated during 3 phases of the COP trajectory during a gait initiation task. RESULTS: The peak magnitude of the COP-COM distance was significantly greater during the end of the single-support phase in the less disabled patients (H&Y score or=2.5) (P=.004). CONCLUSIONS: The differences in COP-COM distances between these H&Y groups suggest that patients with PD who have impaired postural control produce shorter COM-COP distances than do persons without clinically detectable balance impairment. This method of evaluation could prove a useful quantitative index to examine the impact of interventions designed to improve ambulation and balance in PD.

Aged↗

PubMed1989

A microcomputer system for clinical signal analysis of vestibular laboratory.

A vestibular laboratory system was implemented for clinical testing and medical examination of patients with balance disorders. Programs for analysis of postural control and eye movements were made for a microcomputer. The microcomputer system can be used by a nurse without technical education. The system has now been used for two years at the laboratory.

Eye Movements↗

PubMed2005

Methods for dynamic balance training during standing and stepping.

The regaining of walking ability is one of the main goals of rehabilitation following stroke. An important aspect of bipedal locomotion is efficient balancing of the trunk. In this article a novel methodology for dynamic balance training during standing and stepping is presented in a commercially available mechanical balance training device. A case study that lasted for two-weeks with two half-hour training sessions per day, involving a single subject with chronic hemiparesis, investigated the effects of the proposed dynamic balance training. Instrumented kinesiological evaluation of the subject's gait indicated important improvement in the subject's postural control during walking. Finally, the possibility of combining therapeutic functional electrical stimulation of selected lower extremity muscles with the methodology for dynamic balance training presented here is discussed.

Hemiplegia↗

PubMedDate not supplied

Postural stability in the elderly: empirical confirmation of a theoretical model.

The study investigated whether physiological factors related to specific body systems can explain postural control as measured by the scalar distance at a given time between the center of pressure (COP) and the center of mass (COM), the COP-COM variable. The data from 46 healthy subjects and 29 subjects with disabilities due to stroke or diabetic peripheral neuropathy were analyzed. The biomechanical variable COP-COM was determined using two force platforms and an optoelectric system. Three systems were considered as possible predictors of the COP-COM amplitude: sensory (somatosensory and vision), musculoskeletal and central processor. A confirmatory analysis was done using structural equation modeling. Strength explained 23.74% of the COP-COM amplitude in the antero-posterior (A/P) with eyes open (EO) condition, and in the medio-lateral (M/L) direction strength explained 40.73 and 28.75% in the EO and eyes closed (EC) respectively. In the A/P direction with EC, 51.75% of the COP-COM amplitude variance was explained mainly by the somatosensory system. This study highlight the role of peripheral somatosensory input and muscle strength in the maintenance of postural stability during quiet stance in the elderly. The indirect action of the different systems on the COP-COM amplitude supports the systems theory.

Aged↗