PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Postural Balance”

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 217 records · Page 12Linked to original sources
PubMedDate not supplied

Step length variability at gait initiation in elderly fallers and non-fallers, and young adults.

BACKGROUND: Normal aging is characterized by functional changes in the sensory, neurological and musculoskeletal systems. These changes affect several motor tasks including postural balance and gait. Gait variability has been suggested to be an important predictor of the risk of falling: the age-related increased variability may result of errors in the control of foot placement and/or center of mass displacement. Falls occur most frequently in elderly populations who scored poorly during transfer of quasi-static to dynamic situations, turning and reaching tasks in clinical tests. This suggests that gait initiation, which is a transient phase between standing and walking, could contribute to an increase in variability because, for elderly, muscular synergies associated with gait initiation occur less frequently than for young adults. OBJECTIVE: To examine if gait initiation and more particularly the variability of the first step length and the duration of the first double support period are more important for elderly fallers than for eldery non-fallers and young adults. METHODS: Elderly fallers, elderly non-fallers, and young adults were asked to initiate gait and walk at least 3 strides. Spatio-temporal characteristics of the first step and following strides were collected and across-trials variability analysed. RESULTS: Elderly fallers showed a much smaller first step length and a longer duration of the double support period. The first step length variability of elderly fallers was more than twice greater than that observed for elderly non-fallers. CONCLUSION: Considering the importance of proper initial foot placement for gait initiation and for stepping recovery responses, the first step length variability observed for the elderly fallers may be an important predictor of postural problems.

Accidental Falls↗
PubMed1997

The effects of hyperventilation on postural control mechanisms.

The effect of hyperventilation on postural balance was investigated. Voluntary hyperventilation increased body sway in normal subjects, particularly in the sagittal plane. The possibility that this hyperventilation-induced unsteadiness is due to interference with lower limb somatosensory input, vestibular reflexes or cerebellar function was assessed. (i) The effect of hyperventilation on peripheral compound sensory action potentials (SAPs) and somatosensory evoked potentials (SEPs) (recorded centrally, from the scalp) elicited by electrical stimulation of the sural nerve was measured in six normal adults. A reduction in the scalp SEP amplitude and an increase in the peripheral SAP amplitude were observed during hyperventilation, which reversed during the recovery period. These changes indicate increased peripheral neural excitability which could lead to a higher level of ectopic activity; the latter would interfere with central reception of peripheral input. (ii) The click-evoked vestibulo-collic reflex was recorded to study the effect of hyperventilation on vestibulo-spinal activity. EMG recordings from both sternocleidomastoid muscles of six healthy subjects were made in response to loud clicks presented to either ear. Neither the amplitude nor the latency of the response were altered significantly by hyperventilation. (iii) Eye-movement recordings were obtained in the six normal subjects to assess the effect of hyperventilation on the vestibulo-ocular reflex and its visual suppression, the latter being a function largely mediated by the cerebellum; no changes were detected. (iv) Three-dimensional eye-movement recordings and body-sway measurements were obtained in six patients with longstanding unilateral vestibular loss in order to evaluate if hyperventilation disrupts vestibular compensation. In all patients, a horizontal nystagmus either appeared or was significantly enhanced for > or = 60 s after voluntary hyperventilation. Sway was also enhanced by hyperventilation in these patients, particularly in the frontal plane. This study suggests that hyperventilation disrupts mechanisms mediating vestibular compensation. The increase in sway may be, at least partly, mediated by deranged peripheral and central somatosensory signals from the lower limbs. Hyperventilation seems to spare vestibular reflex activity and cerebellar-mediated eye movements.

Acoustic Stimulation↗
PubMed1996

Meta-analysis of the sensitivity and specificity of platform posturography.

OBJECTIVE: To compare the sensitivity and specificity of platform posturography with other vestibular tests for patients with peripheral vestibular deficits (PVD), Meniere's disease, benign paroxysmal positional vertigo (BPPV), and central nervous system-vestibular impairment (CNS). DATA SOURCES: A computed search was conducted using the Index Medicus database (1966-1994) and Current Contents Science Editions. STUDY SELECTION: Studies were selected for analysis if the article addressed the sensitivity and/or specificity of platform posturography, compared posturography with another objective test of vestibular function, identified the basis for abnormal test results, and reported the data with sufficient detail to calculate an effect size from a 2 x 2 contingency table. DATA EXTRACTION: A count of the normal and abnormal test results for posturography and the criterion standard were retrieved from each article, analyzed using a chi 2 statistic, and converted to an effect size. A positive effect size indicated that posturography identified abnormalities in patients who had normal tests on the criterion standard. DATA SYNTHESIS: Sensitivity and specificity of posturography were about 50%. The overall effect size was small (0.13) but positive. The diagnostic category had a significant influence on the predictive value of abnormal results (73% for Meniere's disease and BPPV, compared with 41% for PVD, and 44% for mixed CNS and PVD (F2,12 = 5.26, P = .02) and on the magnitude of the effect size (0.41 for mixed CNS and PVD compared with 0.22 for Meniere's disease and BPPV, and -0.10 for PVD (F2,12 = 13.95, P = .001). CONCLUSIONS: Platform posturography provides a measurable supplement to the standard vestibular examination. The enhancement was most notable when the target population included patients with CNS deficits.

Abstracting and Indexing↗
PubMed1999

Assessing muscle stiffness from quiet stance in Parkinson's disease.

In previous studies, we developed a postural stiffness measure that is extracted from foot center-of-pressure (COP) trajectories from quietly standing individuals and is based on an analytical mechanical model of posture control. Here we apply this measure to patients with Parkinson's disease (PD). We correlated the postural stiffness measure with different clinical rating scales, obtained from patients. Kendall's rank correlation was highly significant between the stiffness measure and rigidity, bradykinesia, posture impairment, gait, and leg agility, respectively, as rated by the Unified Parkinson's Disease Rating Scale. These results provide further evidence that a higher intrinsic muscle stiffness may contribute to the aforementioned clinically defined symptoms. From a clinical standpoint, this work indicates that the proposed postural stiffness measure may be useful as an assessment tool for the evaluation of PD patients subsequent to pharmacological and surgical treatment.

Disability Evaluation↗
PubMed1999

Does deep brain stimulation of the nucleus ventralis intermedius affect postural control and locomotion in Parkinson's disease?

The purpose of this study was to evaluate the effect of unilateral stimulation of the nucleus ventralis intermedius (VIM) on parkinsonian signs like postural stability and locomotion with respect to the severity of Parkinson's disease (PD). Seven patients with idiopathic PD were included in the study. Changes in visual cues on postural stability and step initiation were assessed on a fixed platform system with VIM stimulation switched either on (VIM ON) or off (VIM OFF), and compared with a control group of seven age-matched normal individuals. Sway scores (area and path) were significantly (p <0.05) higher in the parkinsonian patients with VIM OFF than with VIM ON as well as compared with the control subjects. No correlation was obtained between extent of sway scores and severity of contralateral tremor after cessation of VIM stimulation. Locomotion parameters, by contrast, were not influenced by VIM stimulation: latency until step initiation and walking-cycle time were the same among parkinsonian patients as among normal individuals, both in the presence and in the absence of VIM stimulation. In conclusion, our results indicate that tremor suppression by VIM stimulation improves postural stability.

Aged↗
PubMed2000

Lateral leg raising in patients with Parkinson's disease: influence of equilibrium constraint.

Patients with Parkinson's disease often have difficulty maintaining postural stability. This impairment is attributed to postural adjustment deficits. We studied the postural adjustments associated with the performance of two complex tasks which differed only in the final equilibrium constraints. Ten patients with Parkinson's disease and six age-matched control subjects were asked to raise one leg laterally to an abduction angle of approximately 45 degrees as fast as possible to the right or left in random order. In the first series of tests, the subjects were instructed to maintain the leg at 45 degrees, whereas in the second series they were instructed to place their foot back on the ground. Recordings included ground reaction forces and kinematics. In the patients with Parkinson's disease the final posture for the first task was never maintained. The strategy used to shift the body weight was different for the two groups. In control subjects, it was initiated by a whole body rotation around the ankle followed by a trunk inclination around the hip. Conversely, in patients with Parkinson's disease, the shift of the body weight was initiated by a trunk inclination around the hip and then by a whole body rotation around the ankle. The amplitude of the trunk inclination toward the supporting side was smaller than in the control subjects. The second task with less severe equilibrium constraints was, on the whole, better performed by the patients even though the same postural adjustment deficits were present.

Aged↗
PubMed1980

Development of the brain stem in the rat. III. Thymidine-radiographic study of the time of origin of neurons of the vestibular and auditory nuclei of the upper medulla.

Groups of pregnant rats were injected with two successive daily doses of 3H-thymidine from gestational days 12 and 13 (E12 + 13) until the day before parturition (E21 + 22). In adult progeny of the injected rats the proportion of neurons generated on specific embryonic days was determined quantitatively in the vestibular and auditory nuclei of the upper medulla. In the vestibular nuclei, neurons are generated between days E11 and E15 in an overlapping sequential order, yielding a lateral-to-medial and a rostral-to-caudal internuclear gradient. In the lateral vestibular nucleus peak production time is day E12; in the superior nucleus, E13; in the inferior nucleus, E13 and E14; and in the medial nucleus, E14. The early generation of neurons of the lateral vestibular nucleus may reflect the early differentiation of the circuit from the gravity receptors (utricle) to neurons of the spinal cord controlling postural balance. The later production of neurons of the superior vestibular nucleus may reflect the subsequent differentiation of the circuit from the rotational receptors (semicircular canals) to the neurons of the brain stem controlling eye movements. The generation time of neurons of the nucleus prepositus hypoglossi overlaps with that of the medial vestibular nucleus. The neurons of the anteroventral and posteroventral cochlear nuclei are produced from days E13 to E17, with no temporal differences between the two nuclei. The neurons of the dorsal cochlear nucleus are generated over a very long time span, beginning on day E12 and extending into the postnatal period. There is a sequence in the production of neurons forming the different layers of the dorsal cochlear nucleus in the following order: pyramidal cells, cells of the inner layer, cells of the outer layer and, finally, cells of the granular layer. There is also a sequential production of neurons in four nuclei of the superior olivary complex. In the lateral trapezoid nucleus peak production time is day E12; in the medial superior olivary nucleus, day E13; in the medial trapezoid nucleus, day E15; and in the lateral superior olivary nucleus, day E16. This order yields a medial-to-lateral gradient in the dorsal aspect of the superior olivary complex, and a lateral-to-medial gradient ventrally. These mirror-image gradients were also seen intranuclearly in the lateral superior olivary nucleus and the medial trapezoid nucleus. The cytogenetic gradients could not be related to tonotopic representation; however, they could be related to the lateral location of ipsilateral cochlear nucleus input to the lateral superior olivary nucleus and the medial location of the contralateral cochlear nucleus input to the medial trapezoid nucleus.

Animals↗
PubMed2005

Development of somatosensory-motor integration: an event-related analysis of infant posture in the first year of independent walking.

The ability to integrate sensation with action is considered an important factor underlying the development of upright stance and locomotion. While many have studied sensory influences on posture, the nature of these influences and how they change with development have yet to be thoroughly characterized in infancy. Six infants were examined from 1 month prior to walk onset until 9 months of independent walking experience while standing quietly and touching either a static or a dynamic surface. Five adults were examined performing an analogous task. An event-related, time-frequency analysis was used to assess the relationship between postural sway and the motion of the somatosensory stimulus. Phase consistency between sway and stimulus was observed for both adults and infants, and with walking experience the infants increased their phase consistency rather than changing aspects of response amplitude. It is concluded that walking experience provides opportunities for an active tuning of sensorimotor relations for adequate estimation of body position in space and thus facilitates refined control over temporal aspects of postural sway.

Adult↗
PubMed1992

The development of righting reflexes in the pouch young of the marsupial Dasyurus hallucatus.

The development of righting was studied in the young of Dasyurus hallucatus, a small marsupial from northern Australia. Young were tested from birth to weaning. Righting began at 40 days, when tactile input on the snout triggered rotation to prone. Over the next 15-20 days, asymmetrical tactile input on the body triggered righting movements by the hindlegs (and later by the forelegs). Vestibular righting reflexes developed after these tactile righting reflexes. Furthermore, asymmetrical vestibular righting (i.e., when the young are held laterally in the air) developed before symmetrical vestibular righting (i.e., when held downward by the pelvis or placed supine in water). Vestibular righting triggered by falling supine in the air did not develop until about 80 days. This study further demonstrates that righting behavior does not consist of a single, integrated motor pattern, but a suite of motor patterns having independent control mechanisms and patterns of development.

Aging↗
PubMedDate not supplied

The association of abnormal cerebellar function in children with developmental coordination disorder and reading difficulties.

Children with developmental coordination disorder/dyspraxia (DCD) are at high risk of reading and writing delay. The difficulties with motor skills are heterogeneous and many children have features of poor cerebellar function, reflected in problems with posture, balance and fast accurate control of movement. This study confirmed a high level of parental reporting of reading and writing delay in a clinical group of 23 children with DCD, defined on the basis of both clinical examination and standardized testing of motor function. Direct measurement of reading delay, identified still further children in the group. Those children with reading delay had associated findings typical of phonological awareness difficulties. The children also underwent a standardized test of neurological function and although they all had difficulties with cerebellar function, no distinctive pattern emerged for those whose presentation was complicated by delayed reading and writing. Both the children with DCD and 136 typically developing children, completed the pilot parental questionnaire on gross motor skills. The three skills of catching a ball, jumping on a moving playground roundabout and handwriting, distinguished the children with DCD. This study therefore confirms that children with DCD should be assessed for difficulties in phonological awareness. Additionally, children aged between 7 and 12 years are on the whole, highly competent in a range of gross motor skills and further study might determine whether a simple parental questionnaire might detect children who would benefit from further assessment. The study also suggests that all the children with DCD have cerebellar dysfunction and further work with a larger group might determine particular patterns associated with reading delay.

Cerebellum↗
PubMed2002

Vestibular compensation after ganglionectomy: ultrastructural study of the tangential vestibular nucleus and behavioral study of the hatchling chick.

The tangential nucleus is a major part of the avian vestibular nuclear complex, and its principal cells are structurally distinctive neurons participating in the vestibuloocular and vestibulocollic reflexes. After unilateral peripheral vestibular lesion, a behavioral recovery of function defined as vestibular compensation is observed. Because sprouting and hypertrophy of synapses have been reported in other regions of immature animals after central nervous system injury, we investigated whether this also occurs in the vestibular nuclei during compensation. To test this hypothesis, unilateral vestibular ganglionectomy was performed on 4-6-day-old hatchlings and vestibular function was tested during the next 2 months. Degeneration and evidence for regeneration of synapses were studied in the tangential nucleus at 1, 3, 7, and 56 days after surgery. Spoon endings, large vestibular terminals on the principal somata, degenerated 1-3 days after surgery. However, the small synaptic terminals showed no significant change in the percentage or number covering the soma or in mean terminal lengths in the deafferented or contralateral tangential nucleus. Furthermore, there was no evidence of neuron death in the tangential nucleus. Vestibular compensation occurred in three stages: 0-3 days, when vestibular synapses degenerated and severe behavioral deficits were seen; 4-9 days, when primary vestibular fibers degenerated centrally and marked improvement in both the static and the dynamic symptoms were observed; and 10-56 days, when changes in neuronal morphology were not detected but the dynamic symptoms gradually improved. Accordingly, after unilateral vestibular ganglionectomy, vestibular compensation proceeded without ultrastructural evidence of sprouting or hypertrophy of axosomatic synapses in the hatchling tangential nucleus. This rapid behavioral recovery of function distinguishes the vestibular system from other sensory systems, which, in general, exhibit much less robust recovery after injury to their peripheral receptors.

Adaptation, Physiological↗