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PubMed1993

Test-retest reliability of two tiltboard tests in children.

BACKGROUND AND PURPOSE: Most clinical evaluations of postural control in children are relatively subjective and have not been tested for reliability of scoring. The purpose of this study was to investigate the test-retest reliability of measurements obtained with two tiltboard tests. SUBJECTS: Subjects were 18 children, aged 53 to 81 months (mean = 64.4, SD = 8.3), who were typically developing (TD group) and 18 children, aged 50 to 79 months (mean = 63.3, SD = 8.4), with developmental delays (DD group). METHODS: Each child was tested using the two tilt-board tests and was then retested using the same tests approximately 1 week later. The maximum angle of tiltboard tilt prior to any postural adjustment by the child was recorded. RESULTS: Intraclass correlation coefficients for test-retest reliability (two-way, random-effects, repeated-measures model) ranged from .49 to .54 for the TD group and from .52 to .82 for the DD group. Angles were higher for both groups for the second test. CONCLUSION AND DISCUSSION: The results suggest that these tiltboard tests do not give stable and reliable measurements across test sessions. Before these tests can be used to document change in postural control abilities across time, further research is warranted.

Child↗

PubMed2005

Effects of whole-body vibration in patients with multiple sclerosis: a pilot study.

OBJECTIVE: To examine whether a whole-body vibration (mechanical oscillations) in comparison to a placebo administration leads to better postural control, mobility and balance in patients with multiple sclerosis. DESIGN: Double-blind, randomized controlled trial. SETTING: Outpatient clinic of a university department of physical medicine and rehabilitation. SUBJECTS: Twelve multiple sclerosis patients with moderate disability (Kurtzke's Expanded Disability Status Scale 2.5-5) were allocated either to the intervention group or to the placebo group. INTERVENTIONS: In the intervention group a whole-body vibration at low frequency (2.0-4.4 Hz oscillations at 3-mm amplitude) in five series of 1 min each with a 1-min break between the series was applied. In the placebo group a Burst-transcutaneous electrical nerve stimulation (TENS) application on the nondominant forearm in five series of 1 min each with a 1-min break between the series was applied as well. MAIN OUTCOME MEASURES: Posturographic assessment using the Sensory Organization Test, the Timed Get Up and Go Test and the Functional Reach Test immediately preceding the application, 15 min, one week and two weeks after the application. The statistical analysis was applied to the change score from preapplication values to values 15 min, one week and two weeks post intervention. RESULTS: Compared with the placebo group the intervention group showed advantages in terms of the Sensory Organization Test and the Timed Get Up and Go Test at each time point of measurement after the application. The effects were strongest one week after the intervention, where significant differences for the change score (p = 0.041) were found for the Timed Get Up and Go Test with the mean score reducing from 9.2 s (preapplication) to 8.2 s one week after whole-body vibration and increasing from 9.5 s (preapplication) to 10.2 s one week after placebo application. The mean values of the posturographic assessment increased from 70.5 points (preapplication) to 77.5 points one week after whole body vibration and increased only from 67.2 points (preapplication) to 67.5 points one week after the placebo application. No differences were found for the Functional Reach Test. CONCLUSION: The results of this pilot study indicated that whole-body vibration may positively influence the postural control and mobility in multiple sclerosis patients.

Adult↗

PubMed2006

Leg orientation as a clinical sign for pusher syndrome.

BACKGROUND: Effective control of (upright) body posture requires a proper representation of body orientation. Stroke patients with pusher syndrome were shown to suffer from severely disturbed perception of own body orientation. They experience their body as oriented 'upright' when actually tilted by nearly 20 degrees to the ipsilesional side. Thus, it can be expected that postural control mechanisms are impaired accordingly in these patients. Our aim was to investigate pusher patients' spontaneous postural responses of the non-paretic leg and of the head during passive body tilt. METHODS: A sideways tilting motion was applied to the trunk of the subject in the roll plane. Stroke patients with pusher syndrome were compared to stroke patients not showing pushing behaviour, patients with acute unilateral vestibular loss, and non brain damaged subjects. RESULTS: Compared to all groups without pushing behaviour, the non-paretic leg of the pusher patients showed a constant ipsiversive tilt across the whole tilt range for an amount which was observed in the non-pusher subjects when they were tilted for about 15 degrees into the ipsiversive direction. CONCLUSION: The observation that patients with acute unilateral vestibular loss showed no alterations of leg posture indicates that disturbed vestibular afferences alone are not responsible for the disordered leg responses seen in pusher patients. Our results may suggest that in pusher patients a representation of body orientation is disturbed that drives both conscious perception of body orientation and spontaneous postural adjustment of the non-paretic leg in the roll plane. The investigation of the pusher patients' leg-to-trunk orientation thus could serve as an additional bedside tool to detect pusher syndrome in acute stroke patients.

Adult↗

PubMed2006

The Physical Performance Test as a predictor of frequent fallers: a prospective community-based cohort study.

OBJECTIVE: To construct a risk model in order to identify elderly individuals at risk of frequent falling. DESIGN: Prospective community-based cohort study over 12 months. SETTING: Baseline measures were performed at a local community centre. SUBJECTS: Two hundred and sixty-three community-dwelling elderly people (mean age 72 years). MEASUREMENTS: A variety of variables were evaluated, including medical, psychological, sensory, physical and postural control measurements. Fall incidence was monitored retrospectively and during one-year follow-up. RESULTS: Logistic regression analysis showed that polypharmacia was the most prominent medical fall predictor with an odds ratio (OR) of 1.29 (P= 0.005), poor visual acuity the best sensory predictor (OR = 0.84; P= 0.009) and general fear of falling the most crucial psychological predictor (OR = 3.25; P< 0.001). Increased postural sway in near-tandem stance with eyes open was selected as the best balance predictor for falls (OR = 5.60; P= 0.010), followed by delayed anteroposterior movement velocity during rhythmic weight shifts (OR = 0.42; P= 0.004). The best physical predictor was a low score on the Physical Performance Test (OR =4.16; P< 0.001), followed by decreased maximal handgrip strength (OR = 0.87; P< 0.001) and increased timed chair-stands (OR = 1.13; P= 0.003). Step-by-step regression analysis revealed a risk model for the prediction of future falls, as a combination of the Physical Performance Test and maximal handgrip strength. CONCLUSION: This study confirms the multicausality of falls, since medical, psychological, sensory, postural control as well as physical variables provides a predictive value. The composed fall risk model was mainly physically oriented.

Accidental Falls↗

PubMed1980

Control of postural changes of end expiratory volume (FRC) by airways slowly adapting mechanoreceptors.

We recorded the e.m.g. activity of the diaphragm and of an abdominal muscle (ext. oblique) and the respiratory volume in anesthetized rabbits challenged with head-up tilting and positive pressure breathing (PPB). Both maneuvers determined an inhibition of inspiratory activity and an activation of abdominal muscles, the latter being especially marked with tilting. After cervical vagotomy neither the inspiratory inhibition nor the abdominal recruitment was present during tilting and PPB and the FRC increase was more pronounced. Sulphur dioxide was given in the inspired air (200 ppm) to selectively block the slowly adapting mechanoreceptors. Such blockade was indicated by the absence of the Hering-Breuer inflation reflex. The permanence of other respiratory reflexes was shown by a parodoxical response to inflation and by a still evident response to deflation. With SO2 block, both tilting and PPB did not elicit either the inspiratory inhibition or the abdominal muscles activation, leading to an FRC shift similar to that observed after vagotomy. We conclude that the slowly adapting mechanoreceptors subserve a reflex mechanism relevant in controlling FRC.

Abdominal Muscles↗

PubMed2003

[Influence of obesity on postural capacities of teenagers. Preliminary study].

OBJECTIVE: The purpose of this work was to define the influence of obesity on static postural control of teenagers. SUBJECTS AND METHOD: Nine obese subjects and seven non-obese subjects were characterised with stabilometric data of surface, of lengths and spontaneous sway in the lateral (X) and antero-posterior (Y) axis with open eyes and closed eyes in two conditions on firm floor and foam floor condition. RESULTS: For length data, significative differences were observed between the two groups for the opened eyes condition (p < 0.02) and eyes closed (p < 0.03) during foam floor condition. CONCLUSION: During experimental solicitations, obesity influences significatively the postural control of teenagers. Instead of systematic statistic differences, we observed a decrease in balance capacities of obese subjects. The effects of fat tissue distributions were not verified.

Adolescent↗

PubMed2004

The influence of Tai Chi training on the center of pressure trajectory during gait initiation in older adults.

OBJECTIVE: To determine if a program of intense Tai Chi exercise that has been shown to reduce the risk of falling in older adults improves postural control by altering the center of pressure (COP) trajectory during gait initiation. DESIGN: Before-after trial. SETTING: Biomechanics research laboratory. PARTICIPANTS: Twenty-eight older adults transitioning to frailty who participated in either a 48-week intervention of intense Tai Chi training or a wellness education (WE) program. INTERVENTIONS: Eight Tai Chi forms emphasizing trunk rotation, weight shifting, coordination, and narrowing of lower-extremity stance were taught twice weekly. WE program participants met once a week and received lectures focused on health. Main outcome measures The COP was recorded during gait initiation both before and after the 48-week intervention by using a forceplate sampling at 300 Hz. The COP trajectory was divided into 3 periods (S1, S2, S3) by identifying 2 landmark events. Displacement and average velocity of the COP trace in the anteroposterior (x) and mediolateral (y) directions, as well as smoothness, were calculated. RESULTS: Tai Chi training increased the posterior displacement of the COP during S1 and improved the smoothness of the COP during S2. CONCLUSIONS: Tai Chi improved the mechanism by which forward momentum is generated and improved coordination during gait initiation, suggesting improvements in postural control.

Aged↗

PubMed2003

The effect of two types of virtual reality on voluntary center of pressure displacement.

Voluntary movements result in internal perturbations of balance and equilibrium. One variable regulated during movement is the position of the center of pressure (COP). Sensory information from the visual, vestibular and somatosensory systems is used in establishing relevant frames of reference for postural control. In this study, we were interested in determining whether different limitations of COP movement occur when different approaches to delivering virtual environments are used and when visual information incoherent with vestibular and somatosensory information is provided. Eighteen healthy adults completed voluntary lateral reaches under three conditions: continuous lateral reach (CLR), flatscreen virtual reality (FS), and head-mounted display virtual reality (HMD). Reaching behavior was indexed by force plate measures of maximum anterior-posterior and lateral displacement of the COP. The COP movement decreased in the lateral direction in the HMD condition relative to the FS. The maximum range of COP movement in the anterior-posterior direction increased as a function of reaching task with HMD realizing the greatest amount of movement. The lack of an exocentric frame of reference in HMD coherent with information from other sensory systems results in limiting COP movement within the base of support (BOS) in order to decrease the challenge to the postural control system.

Adult↗

PubMed2006

Modeling postural instability with Galvanic vestibular stimulation.

In this study the effect of a pseudorandom binaural bipolar Galvanic stimulus generated by a sum of nonharmonically related sine waves on postural control was functionally assessed using computerized dynamic posturography (CDP), and the results compared to vestibulopathic patient populations and astronauts exposed to microgravity. The standardized CDP test battery comprised six sensory organization tests (SOTs) that combined three visual conditions (eyes open, eyes closed, and sway-referenced vision) with two proprioceptive conditions (fixed and sway-referenced support surfaces). Subjects (12) performed 18 randomized trials (three trials of each of the six SOTs) as a baseline, repeated the 18 trials with Galvanic vestibular stimulation (GVS), and then performed a post-GVS baseline. A 10 min rest period was inserted between each test battery. Anterioposterior postural sway increased significantly and was in the abnormal range (fifth percentile) during GVS for SOTs where visual input was compromised (sway-referenced surround) or absent. Postural stability returned to baseline when GVS was removed. An analysis of sensory input scores (somatosensory, visual, and vestibular) demonstrated the specificity of GVS in distorting vestibular input to postural control. The SOT scores observed in astronauts on landing day did not differ significantly to that generated by GVS in our normal subjects. GVS also induced a similar pattern of instability on CDP as profound bilateral vestibular loss, although not as severe. The results suggest that unpredictably varying GVS quantitatively and qualitatively models postural instability of vestibular origin.

Adult↗

PubMed2004

Does footedness or hemispheric visual asymmetry influence centre of pressure displacements?

To isolate the footedness contribution from the hemispheric visual asymmetry contribution to the upright postural control, seven right and six left-footed healthy women were asked to balance on each unipodal stance on an unstable platform for each visual hemispaces. We compared lateral deviations of the centre of pressure when balancing on the left leg and on the right leg in three visual conditions: normal and restricted to each hemifields. Whatever the visual conditions, left-footers displaced the centre of pressure towards the outside of the supporting foot, whereas right-footers displaced it towards the right side for the two feet. Postural control appears to be regulated differently between the two groups of footedness. For left-footers it should be more based upon the perception of the centre of body mass and for right-footers upon the asymmetrical utilization of head receptors.

Adolescent↗

PubMed2001

Nonlinear analysis of orthostatic posture in patients with vertigo or balance disorders.

The stabilometry signals involve irregular and unpredictable components. In order to identify the hidden dynamics that underlie the multi-link networks consisted of the multiple sensory systems, motor components and central integration, we applied a nonlinear analysis to these signals. We evaluated the postural control differences between eyes open and closed by means of the dynamical closeness between two states, known as similarity index, for the patients with vestibular disorders. We were able to demonstrate that some patients (eight of 21) showed a difference between the conventional and nonlinear measures. Especially, the similarity index tended to reflect the clinical course of the vestibular compensation and the findings in the patients with benign paroxysmal positional vertigo (BPPV) demonstrated that its vestibular function may include various pathologies besides canalithiasis. These results suggest that nonlinear analysis can elucidate the complex postural control networks and this procedure may also be able to provide the new findings of the stabilometry examinations.

Adult↗

PubMed2005

Quantitative assessments of the effect of bilateral subthalamic stimulation on multiple aspects of sensorimotor function for patients with Parkinson's disease.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective for the treatment of advanced Parkinson's disease. Most studies have evaluated the effectiveness of DBS of the STN using clinical motor scores or simple timed tests of motor function. There have been few studies that quantitatively assessed the outcome of STN DBS using multiple testing paradigms. In the current study, 11 patients who had bilateral STN DBS were quantitatively evaluated under four conditions using gait, postural control, and gait initiation. The four conditions included the medication on/stimulation on (M_on/S_on), medication on/stimulation off (M_on/S_off), medication off/stimulation on (M_off/S_on), and medication off/stimulation off (M_off/S_off) conditions. DBS of the STN significantly increased walking speed with and without levodopa, but had no influence on the cadence. The addition of levodopa had a minimal additional effect on walking speed. The effect of STN DBS on gait initiation approached the significant level. The mean values of lateral body sway during quiet standing increased moderately with medication and/or DBS, but the changes were not statistically significant. Future studies need to determine whether or not there is a potential negative effect of STN DBS on the postural control.

Adult↗

PubMed1990

Postural dynamics in the standing human.

The purpose of this study was to develop a mathematical model of the linkage dynamics in upright standing, and to use this model to study output principles for postural control. The standing human was modelled in the sagittal plane as a three-segment linkage. Mechanical disturbances were simulated as forces which could be applied at various points in this linkage. An iterative approach was used to find joint torque combinations which would restore balance within 80 ms of these mechanical disturbances. The model predicted that a specific proportional relationship was necessary between the hip, knee and ankle torques in order for balance to be restored. This proportional relationship was shown to be a function of the model structure, but independent of the location, direction and amplitude of the disturbance. These predictions were tested experimentally. A disturbance apparatus was designed to apply an impulsive force to the subjects. The joint torque responses of the subjects were in quantitative agreement with the predictions of the model. The results suggest that a fixed relationship between joint torques may be required to restore balance, and this fixed relationship may make the task of postural control simpler for the nervous system.

Computer Simulation↗

PubMed2003

Acceleration patterns of the head and pelvis when walking on level and irregular surfaces.

The aim of this study was to evaluate acceleration patterns at the head and pelvis while subjects walked on a level and an irregular walking surface, to develop an understanding of how the postural control system responds to challenging walking conditions. Thirty young, healthy subjects walked on a level corridor and on artificial grass underlain with foam and wooden blocks placed in an arbitrary manner. Temporo-spatial gait parameters and acceleration patterns at the head and pelvis were measured. The results revealed that when walking on the irregular surface, subjects were able to maintain their velocity, but adopted a slower and more variable cadence and a significantly longer stride length. The magnitude of pelvis accelerations increased, however head accelerations were not affected by the walking surface. When considered as an overall pattern of movement, these findings suggest that one of the primary objectives of the postural control system when walking on irregular surfaces is head control, and that subjects adapt their stepping pattern on irregular surfaces to ensure that the head remains stable.

Acceleration↗

PubMed2006

Neuromuscular performance and knee laxity do not change across the menstrual cycle in female athletes.

Female athletes incur anterior cruciate ligament ruptures at a rate at least twice that of male athletes. Hypothesized factors for the increased injury risk in females include biomechanical, neuromuscular, and hormonal differences between genders. A wealth of literature exists examining these potential predispositions individually, but the interactions between these factors have not been examined extensively. Our purpose was to investigate changes in neuromuscular control and laxity at the knee across the menstrual cycle of healthy females. Fourteen female collegiate athletes with normal, documented ovulatory menstrual cycles, confirmed ovulation, and no history of serious knee injury participated. The presence and timing of ovulation was determined during a screening cycle with ovulation detection kits and during an experimental cycle with collection of daily urine samples and subsequent analysis of urinary estrone-3-glucuronide (E3G) and pregnanediol-3-glucoronide (PdG), which correlate with circulating estrogen and progesterone. Each subject had measures of knee neuromuscular performance and laxity once during the mid-follicular, ovulatory, and mid-luteal stages of her menstrual cycle. The test battery included assessments of knee flexion and extension peak torque, passive knee joint position sense, and postural control in single leg stance. Knee joint laxity was measured with an arthrometer. Analyses of variance revealed that E3G and PdG levels were significantly different across the three testing sessions, but there were no significant differences in the measures of strength, joint position sense, postural control, or laxity. No significant correlations were found between changes in E3G or PdG levels and changes in the performance and laxity measures between sessions. These results suggest that neuromuscular control and knee joint laxity do not change substantially across the menstrual cycle of females despite varying estrogen and progesterone levels.

Adult↗

PubMed2000

Factors associated with thoracic spinal cord injury, lesion level and rotator cuff disorders.

BACKGROUND: The study was concerned with the secondary functional compromise persons with long-term paraplegia contend with, that has been shown to be associated with wheelchair use. Of particular interest was the relationship between the level of thoracic spinal cord injury (SCI) and factors predisposing to rotator cuff disorders (RCD), one of the most common upper extremity musculoskeletal complications linked with long-term SCI. Disorders of these peri-articular structures have previously been associated with impaired trunk postural control and abnormal muscle strength ratios in both able-bodied groups and in paraplegic athletes. Despite their neurologically intact shoulder joint musculature, high-level and low-level paraplegics have different degrees of trunk and pelvic stability available to them during activities of daily living (ADL). This fundamental functional anatomical difference between high-level and low-level paraplegics had not previously been related to the diagnosis of RCD in a non-athletic long-term paraplegic population. METHODS: A descriptive cross sectional study was undertaken to demonstrate the differences in the prevalence of clinically diagnosed RCD in a high-level (n=22) and a low-level (n=20) group of persons with long-term paraplegia. Any perceived differences were then related to the functional anatomical variations between the two groups. Inferences were made based on factors predisposing to RCD known to exist among both able-bodied and paraplegic athletes. The 42 subjects completed the Wheelchair User's Shoulder Pain Index (WUSPI) to establish the presence or absence of shoulder pain and the Musculoskeletal Function Assessment (MFA) instrument to determine differences in functional ability and perceived degree of difficulty within five categories of ADL. Each participant underwent a clinical examination using validated provocative clinical tests and isometric muscle strength ratio testing. RESULTS: There was a higher prevalence of RCD in the high-level group (P=0.009) which correlated with decreased trunk control (P=0.009). Differences in ability to perform functional tasks were not shown to be greater in the high-level group, although there was a higher degree of perceived difficulty in ADL. Muscle strength imbalances between the shoulder adductors and abductors were shown to be greater in the high-level group. CONCLUSIONS: The results of this study suggest that the functional anatomical differences that exist within paraplegia contribute to the propensity of high-level paraplegic persons to suffer from RCD. These findings send a clear message to service-providers that greater acknowledgement of the differences in trunk postural control specific to the level of thoracic SCI is required. This may have implications for the prescription of wheelchairs, assistive devices and instruction for alternative ADL techniques to this specific population.

Adult↗

PubMed2003

Bobath or motor relearning programme? A follow-up one and four years post stroke.

OBJECTIVE: The purpose of this follow-up one and four years post stroke was to find out whether the initial physiotherapy approach had had any long-term effects on mortality, motor function, postural control, activities of daily living, life quality, follow-up from community services and living conditions. DESIGN: A randomized controlled trial of first time ever stroke patients. Group 1 (n = 33) and group 2 (n = 28) had initial physiotherapy according to the Motor Relearning Programme and Bobath, respectively. MAIN OUTCOME MEASURES: The Motor Assessment Scale (MAS), the Sødring Motor Evaluation Scale (SMES), the Barthel ADL Index, the Nottingham Health Profile (NHP) and Berg Balance Scale were used. The following parameters were also registered: incidence of new strokes, other diseases, use of assistive devices, the patient's accommodation and use of services from the community. RESULTS: The mortality rates were similar in the two groups. In both groups the motor function, postural control and ADL had decreased rapidly, leaving many of the patients dependent and with a high risk of falling. Life quality had increased compared to the acute stage, but was still low in comparison with healthy persons. Patients in both groups lived at home, but were dependent on help from relatives and community services. Physiotherapy as follow-up service was seldom used. The initial physiotherapy approach did not seem to have a major influence on the patients' ability to cope in the long-term. CONCLUSION: This follow-up at one and four years post stroke showed no major influence of two different initial physiotherapy regimens on long-term function. The study confirmed a rapid deterioration of ADL and motor function and an increased dependence on relatives. The study reveals a gap between the intense treatment in the acute phase and little or no follow-up of physiotherapy treatment or other rehabilitation activities later.

Activities of Daily Living↗

PubMed1983

Retention of generalized hair cell patterns in the inner ear of the primitive flatfish Psettodes.

Flatfish are a group of uniquely asymmetrical vertebrates, lying always on one side. This postural control depends on the vestibular receptors of the inner ear. From the most primitive living flatfish, orientations of sensory hair cells in the inner ear were mapped by scanning electron microscopy. The maps of the three otolith organs, the three semicircular cristae, and the macula neglecta (newly discovered here for flatfish) show patterns that are very similar to those in many upright teleosts, particularly perches. Thus, peripheral sensory structure does not require modification for the unusual postural control of flatfish.

Animals↗