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At least 181 records · Page 10Linked to original sources

PubMed2001

Balance control and posture in anxious mice improved by SSRI treatment.

A task requiring dynamic postural stabilisation during locomotion in a conflicting visual vestibular environment (rotating beam), has been devised to assess anxiety-related balance impairments and postural changes in mice. The model, already validated with acutely administered diazepam, was used to assess the action of two chronically administered selective serotonin reuptake inhibitors (SSRIs), fluoxetine and paroxetine. On three behavioural measures (imbalance, elevation of trunk and angle of tail), observed in anxious BALB/cByJ mice, both compounds had the same diazepam-like effects: reduction in number of imbalances, higher elevation of trunk and increase in tail angle. These data suggest, for the first time, that SSRIs should be useful in the treatment of anxiety-induced balance impairments.

Animals↗

PubMed2002

The influence of commercial-grade carpet on postural sway and balance strategy among older adults.

PURPOSE: The purpose of this research study was to examine the effect of a selected commercial-grade carpet on the static balance of healthy, older adults who had not fallen more than twice in the last 6 months. DESIGN AND METHODS: We tested a total of 45 participants. Each participant stood on a computerized balance machine and was subjected to a carpeted versus a noncarpeted condition while exposed to various sensory limitations. We measured both postural sway and balance strategy. RESULTS: The selected commercial-grade carpet did not affect postural sway. The participants were able to adapt to the sensory limitations regardless of whether they were standing on the carpet. Although balance strategy scores were significantly lower during the carpeted conditions, the clinical significance was questionable as the difference between the means was small for practical purposes. IMPLICATIONS: Healthy, older adults did not have difficulty maintaining static balance on the carpeted surface; however, the results could be different if participants who had a history of falling had been included. The results from this study are important and provide a basis of comparison for those individuals who have experienced more than two falls in the last 6 months or who have a history of falling.

Accidental Falls↗

PubMed1996

Influence of dopaminergic medication on automatic postural responses and balance impairment in Parkinson's disease.

It is still unclear why balance impairment in Parkinson's disease (PD) often responds insufficiently to dopaminergic medication. We have studied this issue in 23 patients with idiopathic PD and 24 healthy controls. Our specific purposes were (a) to investigate the contribution of abnormal automatic postural responses to balance impairment in PD and (b) to assess the influence of dopaminergic medication on abnormal automatic postural responses and balance impairment. Standing subjects received 4 degrees "toe-up" rotational perturbations of a supporting forceplate. We bilaterally recorded posturally destabilizing medium latency (ML) responses from the stretched gastrocnemius muscles and functionally corrective long latency (LL) responses from the shortened tibialis anterior (TA) muscles. We also assessed changes in the center of foot pressure (CFP) and the center of gravity (COG). All patients were tested in the "off" and "on" phases. All controls were tested and retested after 1 h. During the off phase, we found enlarged ML amplitudes and diminished LL amplitudes in patients, together with a markedly increased posterior displacement of the COG. The abnormal ML and LL responses were partially responsible for the increased body sway in patients because the initial forward (destabilizing) displacement of the CFP was increased, while the subsequent backward displacement of the CFP (a measure of the corrective braking action of LL responses) was delayed. Abnormal late automatic or possibly more voluntary postural corrections also contributed substantially to the increased body sway. During the on phase, ML amplitudes were reduced in patients but remained increased compared with controls. LL amplitudes no longer differed between both groups due to a modest, possibly dopamine-related increase in patients and a simultaneous decrease in controls. The abnormal CFP displacement was only partially improved by dopaminergic medication. The later postural corrections were not improved at all. Consequently, the increased posterior COG displacement was not ameliorated during the on phase. We conclude that (a) a combination of abnormal automatic and perhaps more voluntary postural corrections contributes to increased body sway in PD and (b) dopaminergic medication fails to improve balance impairment in PD because early automatic postural responses are only partially corrected, while later occurring postural corrections are not improved at all. These electrophysiological results support clinical observations and suggest that nondopaminergic lesions play a significant role in the pathophysiology of postural abnormalities in PD.

Adult↗

PubMed2006

Age-related part taken by attentional cognitive processes in standing postural control in a dual-task context.

The aim of this work was to determine the effects of ageing on the possible mobilisation of cognitive processes in orthostatic postural balance. Seventy-nine individuals of three different age groups were placed in dual-task situations that combined standing postural control with three different cognitive tasks. Two of these three tasks, auditory-verbal and visual-verbal ones, required external information acquisition whereas the third, a mental counting task, did not require such information. The results showed contrasting variations in postural control performances that are an improvement in young subjects during cognitive tasks which required external information acquisition and a deterioration in elderly subjects during cognitive tasks which did not involve external information acquisition. The middle-aged subjects tended to develop these two types of variations simultaneously. These results confirm that cognitive processes could have a role that increases with age in ensuring postural control. The contrasting results observed between the young and old populations highlight that the allocation of cognitive resources to postural control could, on the one hand, contribute to improving postural performance in subjects with mainly automated control and, on the other, perturb this performance in subjects with mainly cognitive control.

Adult↗

PubMed2005

Effect of vision, touch and stance on cerebellar vermian-related sway and tremor: a quantitative physiological and MRI study.

Postural balance is impaired in individuals with pathology of the anterior superior vermis of the cerebellum. Chronic alcoholism, with its known vermian pathology, provides a viable model for studying the relationship between cerebellar pathology and postural stability. Decades of separate study of recovering alcoholics and post-mortem neuroanatomical analysis have demonstrated vermian pathology but few studies have used quantitative posturography, acquired concurrently with quantitative neuroimaging, to establish whether this brain structure-function relationship is selective in vivo. Here, 30 healthy men and 39 chronic alcoholic men, abstinent from alcohol for several months, underwent MRI for volumetric quantitation of the cerebellar vermis and three comparison brain regions, the cerebellar hemispheres, supratentorial cortex and corpus callosum. All subjects also participated in an experiment involving a force platform that measured sway path length and tremor during static standing balance under four sensory conditions and two stance conditions. Three novel findings emerged: (i) sway path length, a physiological index of postural control, was selectively related to volume of the cerebellar vermis and not to any comparison brain region in the alcoholics; (ii) spectral analysis revealed sway prominence in the 2-5 Hz band, another physiological sign of vermian lesions and also selectively related to vermian volume in the alcoholics; and (iii) despite substantial postural sway in the patients, they successfully used vision, touch and stance to normalize sway and reduce tremor. The selective relationship of sway path to vermian but not lateral cerebellar volume provides correlational evidence for functional differentiation of these cerebellar regions. Improvement to virtual normal levels in balance and reduction in sway and tremor with changes in vision, touch and stance provide evidence that adaptive mechanisms recruiting sensorimotor integration can be invoked to compensate for underlying cerebellar vermian-related dysfunction.

Alcoholism↗

PubMed1994

Multisensory training of standing balance in older adults: I. Postural stability and one-leg stance balance.

BACKGROUND: The effects of standing balance training on the ability to maintain stability in both static two-leg and one-leg stance were tested in healthy older adults. METHODS: Subjects (age range 65-90 years) were randomly assigned to a training (n = 12) or control group (n = 12). Training subjects received a 10-hour balance training program which selectively manipulated sensory inputs from the visual, vestibular, and somatosensory systems. RESULTS: Training subjects showed significantly improved stability (root-mean-square values of anteroposterior platform torque) after training in five of the eight training conditions (when somatosensory inputs were changed or when two or more sensory systems were simultaneously manipulated) (p < .006). When tested 4 weeks after completion of training, subjects (a) fell less frequently when the ankle/foot somatosensory inputs were minimized and (b) stood longer on one leg than the control group (p < .001). CONCLUSIONS: Balance training designed to improve intersensory interaction could effectively improve balance performance in healthy older adults.

Accidental Falls↗

PubMed1998

Postural sway and balance testing: a comparison of normal and anterior cruciate ligament deficient knees.

The purpose of this study was to assess postural sway and balance in normal and anterior cruciate ligament (ACL) deficient (ACLD) knees. Performance was assessed in 15 ACLD and 15 matched control (CON) subjects whilst standing on a postural sway meter and on a balance board. On both pieces of apparatus subjects attempted to maintain balance for 30 s under six different conditions; (1) and (2) standing on both legs with eyes open and closed; (3) and (4) standing on the injured leg with eyes open and closed; and (5) and (6) standing on the non-injured leg with eyes open and closed. Performance on the postural sway meter and balance board deteriorated significantly when both ACLD and CON stood on one leg (P<0.01), and when eyes were closed (P<0.01). This was independent of whether the leg was injured or not. The interaction of vision loss and single leg stance resulted in a significant deterioration in balance board performance on the injured leg compared to the non-injured leg in the ACLD group. Results suggest that use of a postural sway meter for predicting function and stability during dynamic activities in ACLD subjects may be inappropriate. Copyright 1998 Elsevier Science B.V.

Journal Article↗

PubMed1996

The effect of trunk support on performance during arm ergometry in patients with cervical cord injuries.

Earlier studies have shown that the diaphragm might have a postural function that could interfere with its respiratory function during arm cycling in patients with cervical cord injuries with impaired elbow extension. The purpose of this study was to evaluate the effect of trunk support on working performance in such patients. Ten patients with low-cervical-cord injuries performed an arm ergometer test without and with trunk support with at least one week between the tests. The work load averaged 30 (20-50) Watt. Oxygen uptake at steady state averaged 0.71 +/- 0.09 l/min without trunk support and 0.64 +/- 0.10 l/min with trunk support, P < 0.05. There was no difference in blood lactate without or with trunk support. Maximum performance time averaged 8.3 +/- 4.3 min without trunk support and 19.5 +/- 8.8 min with trunk support, P < 0.01. Oxygen saturation tended to decrease during work and returned to resting values after termination. This study showed that trunk support during arm ergometry in cervical-cord-injury patients with impaired elbow extension decreased the energy cost during sub-maximal work and increased the time to perform work. The results indicate that trunk stabilisation might improve performance of activities of daily living and that it should also be considered during exercise affecting the postural balance of these patients.

Adult↗

PubMed1976

[Visual stabilization of free stance in infants: a sign of maturity (author's transl)].

The development of the visual contribution to postural stabilization has been tested using a large visual display rotating around the stationary subject's line of sight. This, in the adult, causes a marked optokinetic postural reaction with a shift of the body center of gravity toward the direction of pattern motion. Scalings of the reactions in children between 6 months and 16 years revealed three phases of development: (1) 6--12-month-old-babies show none or very little optokinetic disturbance of their newly acquired ability to sit. With the development of upright stance and gait, optokinetic influences become increasingly important. (2) Children between the age of 2--5 show a marked dependence of postural stability on vision. In them, the disturbing optokinetic stimulus leads to a marked ipsilateral postural deviation or irresistible fall. (3) From 5 to 15 years of age, visual effects on postural balance slowly decrease to their final strength in adulthood--moderate head and body tilt--in response to the rotating stimulus. It is concluded that the optokinetic loop participates rather late in the multisensory process of postural stabilization. The calibration of the three main loops, visual, vestibular, and proprioceptive, seems to be sequential and mutually interactive. Optimal functioning requires the continuous evaluation of the reafferent sensory consequences of self-generated body movements. Optokinetic destabilization of stance requires the maturity of opto-vestibulo-spinal pathways. Its clinical applicability as a maturity test, however, sofar seems limited.

Adolescent↗

PubMed1997

[Asymmetrical body tilt induced by vibration of the Achilles tendon in patients with unilateral vestibular hypofunction].

Unilateral vestibular lesion results in postural balance deficits, which progressively vanish with time compensation. This functional recovery is caused due to the reorganization of the CNS structures and afferent inputs, mainly of the proprioceptive afferentation. Our aim was to determine the postural effect of leg proprioceptive input induced by the Achilles tendon (AT) vibration in standing patients with unilateral vestibular hypofunction. The examined patients (9 patients unilateral vestibular neuritis and 3 patients with Meniere's disease) had unilaterally decreased caloric responses. The control were 20 healthy volunteers with intact vestibular and motor functions. The postural responses evoked by AT vibration were evaluated by the symmetry of centre of pressure (COP) of the subject. The postural responses induced by the AT vibration in the healthy were bilaterally symmetrical. In the patients the body lean evoked by vibration on the side of intact vestibular apparatus was significantly decreased. The AT vibration on the lesioned side evoked practically identical response to the response of healthy subjects. In the repeated examination after 6 months the asymmetry disappeared which was in accordance with the recovered clinical state. The findings of asymmetry of postural COP displacement in patients with acute unilateral vestibular hypofunction documented transitory asymmetry of influence from leg proprioceptive inputs. The direction of decreased postural response to the proprioceptive stimuli was the same as pathological body lean of patient to the side of lesioned vestibular apparatus. This fact allows us to hypothesize that the postural responses evoked by leg proprioceptive inputs, directionally identical with the pathological body lean induced by asymmetry of vestibular afferentation are inhibited. (Fig. 3, Ref. 15.)

Achilles Tendon↗

PubMed2006

[Attentional control of postural stability in institutionalised elderly people: effects of a physical exercise program].

OBJECTIVE: We aimed to examine the effect of a physical activity program on postural sway and on the attentional control of postural abilities in elderly frail adults. METHOD: Twelve older adults (age 81.4+/-9 years) institutionalised in a geriatric care institution participated in the physical activity program posture-balance-mobility (PBM) twice a week (1 hour per session) for 12 weeks. We analysed stabilometric data for surface and length of the center of pressure (COP) sway, with eyes open and eyes closed, under single-task and dual-task conditions on a firm floor before and after the training program. During the static postural evaluation and under the dual-task condition, subjects performed an attention-demanding cognitive task, the random number generation task. RESULTS: Only the length of COP sway was more important under the dual-task condition than under the single-task condition (p=0.05). At baseline, cognitive performance was significantly weaker under the dual-task condition (standing) than under the single-task condition (seated), with eyes closed but not eyes open (p<0.05). However, after the training program, the performance of the cognitive task did not significantly differ between the dual-task condition with eyes closed and the single-task condition with eyes closed. CONCLUSION: The training program allowed elderly subjects to improve their ability to perform an attention-demanding cognitive task while standing still, in particular with their eyes closed. Although balance seemed to be less stable under the dual-task condition than under the single-task condition, these results could be interpreted as an improvement of the attentional control of postural stability.

Aged, 80 and over↗

PubMed1996

Reorientation of visually evoked postural responses by different eye-in-orbit and head-on-trunk angular positions.

We examined the question of whether the position of the eyes in the head and of the head on the trunk influence the direction of visually elicited postural reactions. Normal subjects stood on a force platform viewing a large disc, rotating in the roll plane, always maintained orthogonal to the line of sight. The disc was presented at 0 degree, 30 degrees and 90 degrees to the right or left with respect to the mid-frontal plane of the subject's body and was viewed with various combinations of horizontal eye-in-orbit and head-on-trunk deviations. It was found that the main direction of body sway was always reoriented to be parallel to the disc (e.g. viewing the disc at 30 degrees oriented sway responses at a mean angle of 33 degrees). The largest sway responses were obtained when the disc was parallel to the sagittal plane of the body and was viewed with an ipsilateral eye-neck deviation totalling 90 degrees (head-on-trunk 60 degrees+eye-in-orbit 30 degrees). When eye and head deviations cancelled each other (i.e. eye-in-orbit +30 degrees combined with head-on-trunk -30 degrees), directional effects on sway also cancelled each other out. This result demonstrates that signals of eye-in-orbit and head-on-trunk position have the capability to redirect visuo-motor commands to the appropriate postural muscles. This allows vision to regulate postural balance whatever the position of the eyes in space. We speculate that this function is mediated by eye and neck proprioceptive signals (or alternatively by efference copy) with access to gain control mechanisms in the visuo-postural system.

Adult↗

PubMed2002

Recovery of postural stability following conscious sedation with midazolam in the elderly.

PURPOSE: To investigate the differences in recovery of postural stability, after obtaining similar intravenous sedation levels with midazolam, in elderly and younger patients undergoing dental surgery. METHODS: We studied 15 elderly patients (>65 years) and 15 younger patients (<55 years) after intravenous sedation. Midazolam was carefully titrated over 4-5 min until slow response to verbal commands, ptosis of the eyelid, or slight slurring of speech was obtained. Parameters were postural balance tests and an addition test, as a psychomotor function test. RESULTS: The dose of midazolam in the elderly group (0.045 +/- 0.012 mg.kg(-1)) was 62% of that in the younger group (0.074 +/- 0.026 mg.kg(-1)). In evaluation of the percentile rank of a balance test with a visual feedback system, which contained a dynamic balance element, recovery at 60 min in the elderly group was significantly slower than that in the younger group. However, the recovery times for the balance test and the addition test, at which the significantly changed values were restored to the baseline values, were 120 min and 90 min, respectively, in both groups. CONCLUSION: In the recovery from sedation, elderly patients had more difficulty in acquiring postural adjustment during movement than in maintaining a standing posture. If the dose is carefully administered, however, even elderly patients might be able to return home 2 h after midazolam administration, as could the younger patients.

Journal Article↗

PubMed1991

Alteration of vertical dimension and its effect on head and neck posture.

Previous research has shown a relationship between head posture and rest position of the mandible. Should this relationship really be an interrelationship? Does a change in mandibular posture alone also alter head and neck posture? The purpose of this article is to demonstrate how a change in mandibular posture, specifically an increase in vertical dimension, contributes to craniovertical extension leading to suboccipital compression and upsetting the postural balance between the head and neck. A model of physiologic equilibrium is presented for the craniomandibular articulation.

Adaptation, Physiological↗

PubMed2002

Optimal hand locations for safe scaffold-end-frame disassembly.

Overexertion and fall injuries comprise the largest category of injuries among scaffold workers. A significant portion of these injuries is associated with scaffold-end-frame dismantling tasks, which require both muscle strength and postural balance skills. The commonly used tubular scaffold end frame is 1.52-m wide x 2-m high and weighs 23 kg. Previous studies have indicated that a great muscle strength can be generated when scaffold workers placed their hands symmetrically at knuckle height. However, adequate postural stability can only be reached when the workers placed their hands at the chest or shoulder height, which is near to the height of scaffold-end-frame center-of-mass. A reasonable approach to solve this dilemma is to develop an assistive lifting device, such as a light-weight clip-and-lift bar, that allows workers to place their hands at the height of the center-of-mass of end frames and concurrently allows an optimal hand separation for them to generate an adequate maximum isometric muscle force to safely accomplish the task. This study was conducted to determine the optimal hand location for a conceptual assistive lifting device to mitigate potential postural imbalance while reducing overexertion hazards during scaffold disassembly. This location would be within a window defined by a vertical hand placement between shoulder height and knuckle height and by a horizontal hand separation distance of shoulder width to end-frame width. The whole-body maximum isometric strength of 54 construction workers was measured in nine symmetric scaffold-end-frame disassembly postures, defined by a combination of three vertical hand placements by three horizontal hand separation distances within the aforementioned window. The study apparatus include a computer-controlled data-acquisition system, a custom-fabricated scaffold fixture, and two Bertec force platforms. An analysis of variance showed that the interaction effect of vertical hand placement and hand separation on workers' maximum isometric strength was significant (p < 0.004). A hand location between elbow height and chest height with a hand separation distance of 46 cm (a conceptual, light-weight assistive bar) would allow workers to generate sufficient isometric strength (about twice that of the scaffold weight) to disassemble the typical 23 kg scaffolds while concurrently allowing them to mitigate the likelihood of postural imbalance.

Accidental Falls↗

PubMed2001

Nineteen-hour variation of postural sway, alertness and rectal temperature during sleep deprivation.

Nineteen-hour variation of postural sway, alertness and rectal temperature during sleep deprivation were studied. Alertness decreased gradually at night and remained low until morning. Postural sway in the eyes-closed condition increased during early morning. In six of the eight subjects the greatest sway was observed during the 3-h period when rectal temperature was at its minimum. It is suggested that unbearable sleepiness during sleep deprivation will give rise to measurable impairment of postural balance especially during the time zone of temperature nadir.

Adult↗

PubMedDate not supplied

Visual function in regenerating teleost retina following cytotoxic lesioning.

Teleost fish retinas can regenerate in vivo in adulthood. Retinal and visual function was assessed in adult goldfish following comprehensive retinal destruction by intraocular injection of ouabain. Electroretinograms (ERGs) and the dorsal light reflex (DLR) were used to evaluate the return of visual function. ERGs were detectable in regenerating eyes 50 to 70 days following ouabain injection. Amplitudes of both a- and b-waves increased steadily through day 210 following ouabain treatment, at which time a-wave amplitude was 90% and b-wave amplitude approached 50% of the contralateral control eye. The progressive gain observed in the a-wave was attributed to photoreceptor regeneration. The increase in b-wave amplitude was attributed to an increase in the number of inner nuclear layer cells and the number and efficacy of neuronal connections to or within the inner retina. The photopic spectral sensitivity of the b-wave in regenerating retina closely matched the intrafish control retina, suggesting that the relative numbers of cone photoreceptors was normal in regeneration. The recovery of the DLR (indicated by improved postural balance during regeneration) paralleled electrophysiological gains during retinal regeneration. Fish displayed a marked longitudinal body imbalance toward the control eye following retinal destruction. Improvement in equilibrium was correlated with increasing b-wave amplitudes. When the b-wave reached 50% of control amplitude (30 weeks), normal posture was restored. The return of the ERG indicates that photoreceptors and their synaptic connections must be functional in regenerating retina. Failure of the retina to regenerate produced an abnormal DLR that persisted through 30 weeks and ERGs were not measurable. The return of normal equilibrium indicates that the regenerating retina can establish central connections to the brain, and that the regenerated connections can mediate functional visual behavior.

Animals↗

PubMed2000

Isopropanol and methylformate exposure in a foundry: exposure data and neurobehavioural measurements.

OBJECTIVES: The aim of this study was to determine the dose-effect relationship between solvent exposure and acute neurobehavioural effects at the worksite. METHODS: In a balanced design, ten workers in a Swiss foundry were monitored for 15 days at ten different times during work. Urine samples were taken in the morning and at the time of examination, and personal exposure to isopropanol and methylformate was measured with active samplers. Neurobehavioural tests such as postural balance (bipedal, bipedal blind, monopedal), simple reaction time and digit span of the Neurobehavioural Evaluation System (NES2) and a combined memory and reaction-time test, the combi-test, were performed. A rating of well-being, and the last consumption of alcohol, caffeine, nicotine and medication were reported. RESULTS: Average environmental concentrations of isopropanol were at 44 ppm ( +/- 16 ppm), and at 36 ppm (+/-21 ppm) for methylformate. Maximum values of personal exposure to isopropanol reached barely the maximal allowable concentration (MAC) value (400 ppm); the methylformate personal exposure of three workers exceeded the MAC value (100 ppm). Urine concentrations of methanol were high (3.1 +/- 2.3 mg/l in the morning, 7.8 +/- 4.9 mg/l after exposure) compared with the results of other studies; concentrations of isopropanol were rather low (0.88 +/- 0.73 mg/l after exposure). CONCLUSIONS: Nevertheless, between personal exposure and biomonitoring, linear correlation was found. Methylformate exposure correlated with methanol and formic acid concentration in the urine, and isopropanol exposure with its concentration in the urine. With the neurobehavioural tests used, no solvent effect in relation to the dose could be determined.

2-Propanol↗