Postural control systems in developmental perspective

Higher surface folding of the human premotor cortex is associated with better long-term learning capability

The capacity to learn enabled the human species to adapt to various challenging environmental conditions and pass important achievements on to the next generation. A growing body of research suggests links between neocortical folding properties and numerous aspects of human behavior, but their impact on enhanced human learning capacity remains unexplored. Here we leverage three training cohorts to demonstrate that higher levels of premotor cortical folding reliably predict individual long-term learning gains in a challenging new motor task, above and beyond initial performance differences. Individual folding-related predisposition to motor learning was found to be independent of cortical thickness and intracortical microstructure, but dependent on larger cortical surface area in premotor regions. We further show that learning-relevant features of cortical folding occurred in close spatial proximity to practice-induced structural brain plasticity. Our results suggest a link between neocortical surface folding and human behavioral adaptability.

Postural control before and after transitional locomotor tasks in children on the autism spectrum: A case-control study

BACKGROUND

Instrumented measurements of postural control provide a more accurate insight into the motor development of children with autism. This study aimed to identify postural control deficits in autistic children during quiet standing before and after transient locomotor task. It was hypothesized that the parameters that characterize the trajectory of center of foot pressure (COP) displacement would be higher in autistic children compared to typically developing children.

METHODS

Sixteen autistic children aged 6-10 but without a comorbidity diagnosis, were enrolled in the study group. The control group comprised 16 typically developing peers. The assessment of the transitional task comprised four different conditions: unperturbed and perturbed transition, stepping up, and stepping down tasks. Analysis of the COP signal was carried out for three distinct phases, i.e., phase 1 - quiet standing before step initiation, phase 2 - transit, and phase 3 - quiet standing until measurement completion.

FINDINGS

The two-way ANOVA with a 2 × 4 factorial design (group × testing condition) revealed a group effect on all posturographic variables in the antero-posterior and medio-lateral directions of phase 1 and in the antero-posterior direction of phase 3. The Bonferroni post-hoc test showed the means of all those variables were significantly higher for the autistic than for typically developing children. Group allocation also had an effect on the time of transit and step length, which turned out to be significantly longer in autistic children compared to healthy peers.

INTERPRETATION

Autistic children show increased postural sway before and after transitional locomotor tasks compared to typically developing children. The trial was prospectively registered in the Australian and New Zealand Clinical Trials Registry (no. ACTRN12621001113842; date registered: 23.08.2021).

Spatiotemporal Evolution of Toddlers' Regional Foot Pressure Distribution and Center of Pressure at Antero-Posterior Axis During Learning of Standing

We investigated quiet stance of newly standing toddlers every three months (trimesters) of their second year of life. Their anteroposterior center-of-pressure (CoPx) velocity and centroidal frequency (CFREQ: 2.36 ± 0.10 to 1.50 ± 0.11 Hz) decreased over time. Besides, mean pressures revealed a potential role-sharing of foot regions in learning and control aspects of standing, with hindfoot carrying the highest (23.89 ± 6.47 kPa) pressure while forefoot the lowest (10.26 ± 2.51 kPa). The highest CFREQ of pressure signal was at midfoot. Through regional CoPx, forefoot has manifested the highest CFREQ (2.10 ± 0.40 Hz) and 90% power frequency (90%PF), whereas hindfoot presented the lowest (CFREQ: 1.80 ± 0.33 Hz). CFREQ and 90%PF of pressure and regional CoPx significantly decreased throughout the trimesters.

The impact of exergames on the functional balance of a teenager with cerebral palsy - a case report

PURPOSE

To understand the impact of an intensive rehabilitation program based on exergames in balance and lower limb function in a teenager with cerebral palsy.

METHODS

The rehabilitation program comprised different customised exergames and was delivered in 5 weekly sessions of 30 min for 4 weeks. Pre-, post-, and 1-month Follow-up assessments included the following metrics: Berg Balance Scale (BBS), Dynamic Gait Index (DGI), Gross Motor Function Measure (GMFM), Posturography, and Gait analysis.

RESULTS

We observed increased scores after the intervention of 9/72 points in GMF - Module E (Walk, Run and Jump) and of 9/56 points in BBS, sustained at Follow-up. Changes in function, specifically in the quality and independence of the performance of specific movements such as turning 360°, increased distance reaching forward, walk behind, step over obstacles, and step stairs up and down were also observed. Gait kinematics and Spatio-temporal parameters tended to get closer to the 50th percentile.

CONCLUSIONS

We observed positive changes in motor function of a teenager with cerebral palsy, with sustained increased scores at a 1-month Follow-up. Findings are suggestive that intensive rehabilitation programs using exergames with high customisation features are a potentially valuable rehabilitation tool for training balance in teenagers with Cerebral Palsy.Implications for rehabilitationExergames may be a useful for providing balance training for teenagers who have a mixed form of cerebral palsy.Exergames that require body displacement may be suitable for modulating gait kinematics and spatio-temporal parameters.The customisation of virtual rehabilitation tools seems to impact the motivation and effort of the user positively.

Identifying Postural Instability in Children with Cerebral Palsy Using a Predictive Model: A Longitudinal Multicenter Study

Insufficient postural control and trunk instability are serious concerns in children with cerebral palsy (CP). We implemented a predictive model to identify factors associated with postural impairments such as spastic or hypotonic truncal tone (TT) in children with CP. We conducted a longitudinal, double-blinded, multicenter, descriptive study of 102 teenagers with CP with cognitive impairment and severe motor disorders with and without truncal tone impairments treated in two specialized hospitals (60 inpatients and 42 outpatients; 60 males, mean age 16.5 ± 1.2 years, range 12 to 18 yrs). Clinical and functional data were collected between 2006 and 2021. TT-PredictMed, a multiple logistic regression prediction model, was developed to identify factors associated with hypotonic or spastic TT following the guidelines of "Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis". Predictors of hypotonic TT were hip dysplasia (p = 0.01), type of etiology (postnatal > perinatal > prenatal causes; p = 0.05), male gender, and poor manual (p = 0.01) and gross motor function (p = 0.05). Predictors of spastic TT were neuromuscular scoliosis (p = 0.03), type of etiology (prenatal > perinatal > postnatal causes; p < 0.001), spasticity (quadri/triplegia > diplegia > hemiplegia; p = 0.05), presence of dystonia (p = 0.001), and epilepsy (refractory > controlled, p = 0.009). The predictive model's average accuracy, sensitivity, and specificity reached 82%. The model's accuracy aligns with recent studies on applying machine learning models in the clinical field.

A preliminary investigation into the impact of shock wave therapy and sonotherapy on postural control of stepping tasks in patients with Achilles tendinopathy

Objective

The outcomes of physical therapy are commonly assessed with subjective scales and questionnaires. Hence, a continuous search to identify diagnostic tests that would facilitate objective assessment of symptom reduction in those patients with Achilles tendinopathy who undergo mechanotherapy. The main aim of this study was to evaluate and compare the effectiveness of shock wave and ultrasound treatments, using objective posturographic assessment during step-up and step-down initiation.

Materials and methods

The patients with non-insertional Achilles tendinopathy and pain lasting for more than 3 months were randomly assigned to one of the experimental groups, i.e., radial shock wave therapy (RSWT), ultrasound therapy, or placebo ultrasound. All groups also received deep friction massage as the primary therapy. The transitional locomotor task was performed with the affected and unaffected limb in random order, on two force platforms under two conditions (step-up and step-down). The recording of center of foot pressure displacements was divided into three phases: quiet standing before step-up/step-down, transit, and quiet standing until measurement completion. Pre-intervention measurements were performed and then short-term follow-ups at weeks 1 and 6 post-therapy.

Results

The three-way repeated measures ANOVA showed few statistically significant two-factor interactions between therapy type, time point of measurement and the type of the locomotor task. Significant increases in postural sway were observed in the entire study population throughout the follow-up period. Three-way ANOVAs revealed a group effect (shock wave vs. ultrasound) on almost all variables of the quiet standing phase prior to step-up/step-down initiation. Overall, postural stability before the step-up and step-down tasks appeared to be more efficient in patients who had undergone RSWT compared to the ultrasound group.

Conclusion

Objective posturographic assessment during step-up and step-down initiation did not demonstrate therapeutic superiority of any of the three therapeutic interventions used in patients with non-insertional Achilles tendinopathy.Clinical Trial Registration: The trial was prospectively registered in the Australian and New Zealand Clinical Trials Registry (no. ACTRN12617000860369; registration date: 9.06.2017).

Pediatric Slow-Progressive, but Not Non-Progressive Cerebellar Ataxia Delays Intra-Limb Anticipatory Postural Adjustments in the Upper Arm

We recently investigated the role of the cerebellum during development, reporting that children with genetic slow-progressive ataxia (SlowP) show worse postural control during quiet stance and gait initiation compared to healthy children (H). Instead, children with genetic non-progressive ataxia (NonP) recalled the behavior of H. This may derive from compensatory networks, which are hindered by disease progression in SlowP while free to develop in NonP. In the aim of extending our findings to intra-limb postural control, we recorded, in 10 NonP, 10 SlowP and 10 H young patients, Anticipatory Postural Adjustments (APAs) in the proximal muscles of the upper-limb and preceding brisk index finger flexions. No significant differences in APA timing occurred between NonP and H, while APAs in SlowP were delayed. Indeed, the excitatory APA in Triceps Brachii was always present but significantly delayed with respect to both H and NonP. Moreover, the inhibitory APAs in the Biceps Brachii and Anterior Deltoid, which are normally followed by a late excitation, could not be detected in most SlowP children, as if inhibition was delayed to the extent where there was overlap with a late excitation. In conclusion, disease progression seems to be detrimental for intra-limb posture, supporting the idea that inter- and intra-limb postures seemingly share the same control mechanism.

Balance rehabilitation for postural control in children with Autism Spectrum Disorder: A two-case report study

OBJECTIVE

This study aimed to investigate the effect of balance rehabilitation on postural control in both low and increased cognitive load conditions in two children with Autism Spectrum Disorders (ASD).

METHODS

Two children diagnosed with ASD participated in a 4-week personalized balance rehabilitation program with two sessions per week. We assessed postural control in two single task (ST) conditions with low cognitive load: Eyes Closed (EC), Eyes Open (EO); and in five increased cognitive load conditions. Those dual task (DT) conditions consisted of presenting images representing a neutral condition, sadness, anger, happiness, and fear. Postural control parameters (surface, velocity, medio-lateral and antero-posterior sway amplitudes of the center of pressure (CoP)) were collected by a posturographic platform before and after the balance rehabilitation.

RESULTS

The rehabilitation program resulted in a 30-96% improvement of postural control parameters in the ST condition for both participants. In DT, participant 1 progressed on all conditions while participant 2 progressed on 3 of the 5 conditions (sadness, anger and fear).

CONCLUSION

This suggests that these two children with ASD improved their balance control in both low and increased cognitive load conditions. These encouraging results need to be replicated before recommending balance rehabilitation as standard health rehabilitation in children with ASD.

Acute Effects of a Haptic Anchor System on Postural Sway of Individuals with Parkinson's Disease: A Preliminary Study

Some investigators have demonstrated that an anchor system can improve postural control in elderly persons during balance tasks, but none have reported on the use of this approach in individuals with Parkinson's disease (PD). Therefore, we aimed to evaluate the effect of an anchor system on postural sway in elderly individuals with (n = 13) and without (n = 14) PD. In this cross-sectional study, we measured postural sway with a force platform based on the Clinical Test of Sensory Interaction of Balance (CTSIB). We calculated center of pressure (COP) parameters, as a function of time, based on the ellipse sway area (cm²) and evaluated self-efficacy for postural control based on the degree of difficulty in each task. With the anchor system (i.e., handheld ropes attached to weights on the floor), we observed a significant reduction in the ellipse sway area in the semi-tandem position among individuals with PD (p = .04). For participants without PD, there was no significant difference in sway with or without the anchor system in all positions. Also, for participants with PD, there was an improvement in self-efficacy for postural control associated with the anchor system in several positions while there was only a self-efficacy improvement with the anchor system in the semi-tandem position for those without PD. Acute use of a haptic anchor system reduced postural sway in the semi-tandem position in individuals with PD, and the anchor system generally improved postural control self-efficacy for body sway in individuals with PD.

Prospective association between standing balance and cognitive function in middle-aged and older Chinese adults

Objective

To investigate the association of standing balance with cognitive functions and the rate of cognitive decline among middle-aged and older Chinese adults.

Methods

Participants were selected from China’s Health and Retirement Longitudinal Study. A total of 8,499 subjects aged ≥45 years who participated in wave 1 to wave 3 surveys were included in the final analysis. Standing balance was measured using the tandem test, and participants were categorized into two groups according to their ability to maintain standing balance. Cognitive functions were assessed in three domains: episodic memory, mental status, and global cognition. The associations between standing balance scores, cognitive scores, and the rate of cognitive decline were evaluated using linear regression and linear mixed models.

Results

Compared with participants who successfully completed the standing balance test, those who were unable to complete the test had lower scores on episodic memory [β = −0.18; 95% confidence interval (CI): −0.24, −0.11], mental status (β = −0.28; 95% CI: −0.37, −0.19), and global cognition (β = −0.51; 95% CI: −0.65, −0.38) after 4 years of follow-up. In addition, the rate of decline in mental status and global cognition increased by 0.10 (β = 0.10; 95% CI: 0.07, 0.13) and 0.08 (β = 0.08; 95% CI: 0.04, 0.12) units, respectively, in participants who were unable to complete the test compared with their counterparts.

Conclusion

Good standing balance was significantly associated with higher cognitive function and a lower decline in mental status and global cognition in middle-aged and older Chinese adults.

Unperceived motor actions of the balance system interfere with the causal attribution of self-motion

The instability of human bipedalism demands that the brain accurately senses balancing self-motion and determines whether movements originate from self-generated actions or external disturbances. Here, we challenge the longstanding notion that this process relies on a single representation of the body and world to accurately perceive postural orientation and organize motor responses to control balance self-motion. Instead, we find that the conscious sense of balance can be distorted by the corrective control of upright standing. Using psychophysics, we quantified thresholds to imposed perturbations and balance responses evoking cues of self-motion that are (in)distinguishable from corrective balance actions. When standing immobile, participants clearly perceived imposed perturbations. Conversely, when freely balancing, participants often misattributed their own corrective responses as imposed motion because their balance system had detected, integrated, and responded to the perturbation in the absence of conscious perception. Importantly, this only occurred for perturbations encoded ambiguously with balance-correcting responses and that remained below the natural variability of ongoing balancing oscillations. These findings reveal that our balance system operates on its own sensorimotor principles that can interfere with causal attribution of our actions, and that our conscious sense of balance depends critically on the source and statistics of induced and self-generated motion cues.

Physical Activity Design for Balance Rehabilitation in Children with Autism Spectrum Disorder

One of the characteristics of autism spectrum disorder (ASD) subjects is postural control deficit, which is significant when somatosensory perception is affected. This study analyzed postural stability evolution after physical therapy exercises based on balance training. The study included 28 children with ASD (average age 8 years, average weight 32.18 kg). The rehabilitation program involved performing balance exercises twice a week for three months. Subject assessment was carried out using the RSScan platform. The parameters were the surface of the confidence ellipse (A) and the length of the curve (L) described by the pressure center, which were evaluated before and after the rehabilitation program. Following data processing, we observed a significant decrease in the surface of the confidence ellipse by 92% from EV1 to EV2. Additionally, a decrease of 42% in the curve length was observed from EV1 to EV2. A t test applied to the ellipse surface showed a p = 0.021 and a Cohen’s coefficient of 0.8 (very large effect size). A t test applied to the length L showed p = 0.029 and Cohen’s coefficient of 1.27 mm. Thus, the results show a significant improvement in the two parameters. The application of the program based on physical exercise led to an improvement in the balance of children with autism under complex evaluation conditions.

Proprioceptive manipulations in orthograde posture modulate postural control in low back pain patients: a pilot study

As we stand upright, perceptual afferences are crucial to successfully help generating postural motor commands. Non-Specific Low Back Pain patients frequently demonstrate a lack of proprioceptive acuity, often translating into postural control deficiencies. For the first time, to our knowledge, we studied the postural effects of proprioceptive manipulations in orthograde posture on Non-Specific Low Back Pain patients. Using static posturography recordings, we computed sway speed, speed variance, and the main direction of sway. We also addressed the patient’s subjective feedbacks after being manipulated. Five minutes after the proprioceptive manipulations, our results revealed decreased speed and speed variance outcomes, but the main direction of sway was not modulated. Furthermore, after the proprioceptive manipulations, the patients also self-reported improved clinical outcomes. These findings provide new knowledge opening new fields of research as well as potential treatment strategies in Low Back Pain patients.

Identification of Human Balance Control Responses to Visual Inputs Using Virtual Reality

Human upright balance is maintained through feedback mechanisms that use a variety of sensory modalities. Vision senses information about the motion of the visual surround to improve balance. This study characterized the effects of visual information on human anterior-posterior body sway in upright stance by presenting perturbations through a virtual reality system. This made it possible to use a new visual stimulus, whose amplitude and velocity could be controlled separately. To date, the influences of visual field position and velocity have only been studied independently due to the experimental limitations. The hip displacement, ankle torques, shank angles, and surface EMGs of four major ankle muscles were measured bilaterally as outputs. We found that the root-mean-square (RMS) hip displacement (body angle) increased systematically with visual input amplitude. However, for each amplitude, the RMS body angle increased when input velocity was changed from 2 to 5 degree per second and then decreased from 5 to 10 dps. Spectral analysis was utilized to compute frequency response over a frequency range from 0.04-0.6 Hz. The gain of body sway relative to the perturbation increased with frequency, while the coherence declined. Moreover, as the stimulus amplitude increased, the gain generally decreased, while the mean coherence values always increased. The mean gains and mean coherence values were greatest for the velocity of 5 dps. This study presents a novel experimental approach to study human postural control and augments our knowledge on how the visual information is processed in the central nervous system to maintain balance.

The effect of increased cognitive processing on reactive balance control following perturbations to the upper limb

Reactive balance control following hand perturbations is important for everyday living as humans constantly encounter perturbations to the upper limb while performing functional tasks while standing. When multiple tasks are performed simultaneously, cognitive processing is increased, and performance on at least one of the tasks is often disrupted, owing to attentional resources being divided. The purpose here was to assess the effects of increased cognitive processing on whole-body balance responses to perturbations of the hand during continuous voluntary reaching. Sixteen participants (8 females; 22.9 ± 4.5 years) stood and grasped the handle of a KINARM - a robotic-controlled manipulandum paired with an augmented visual display. Participants completed 10 total trials of 100 mediolateral arm movements at a consistent speed of one reach per second, and an auditory n-back task (cognitive task). Twenty anteroposterior hand perturbations were interspersed randomly throughout the reaching trials. The arm movements with random arm perturbations were either performed simultaneously with the cognitive task (combined task) or in isolation (arm perturbation task). Peak centre of pressure (COP) displacement and velocity, time to COP displacement onset and peak, as well as hand displacement and velocity following the hand perturbation were evaluated. N-back response times were 8% slower and 11% less accurate for the combined than the cognitive task. Peak COP displacement following posterior perturbations increased by 8% during the combined compared to the arm perturbation task alone, with no other differences detected. Hand peak displacement decreased by 5% during the combined compared to the arm perturbation task. The main findings indicate that with increased cognitive processing, attentional resources were allocated from the cognitive task towards upper limb movements, while attentional resources for balance seemed unaltered.

Age-related reduction in peak power and increased postural displacement variability are related to enhanced vestibular-evoked balance responses in females

Adult aging is associated with reductions in muscle function and standing balance control. However, whether sensorimotor function adapts to maintain upright posture in the presence of age-related muscle weakness is unclear. The purpose was to determine whether vestibular control of balance is altered in older compared to younger females and whether vestibular-evoked balance responses are related to muscle power. Eight young (22.6 ± 1.8 years) and eight older (69.7 ± 6.7 years) females stood quietly on a force plate, while subjected to random, continuous electrical vestibular stimulation (EVS; 0-20 Hz, root mean square amplitude: 1.13 mA). Medial gastrocnemius (MG) and tibialis anterior (TA) surface electromyography (EMG) and force plate anterior-posterior (AP) forces were sampled and associated with the EVS signal in the frequency and time domains. Knee extensor function was evaluated using a Biodex multi-joint dynamometer. The weaker, less powerful older females exhibited a 99 and 42% greater medium-latency peak amplitude for the TA and AP force (p < 0.05), respectively, but no other differences were detected for short- and medium-latency peak amplitudes. The TA (<10 Hz) and MG (<4 Hz) EVS-EMG coherence and EVS-AP force coherence (<2 Hz) was greater in older females than young. A strong correlation was detected for AP force medium-latency peak amplitude with center of pressure displacement variability (r = 0.75; p < 0.05) and TA medium-latency peak amplitude (r = 0.86; p < 0.05). Power was negatively correlated with AP force medium-latency peak amplitude (r = -0.47; p < 0.05). Taken together, an increased vestibular control of balance may compensate for an age-related reduction in power and accompanies greater postural instability in older females than young.

A Review of the Potential of Virtual Walking Techniques for Gait Rehabilitation

Virtual reality (VR) technology has emerged as a promising tool for studying and rehabilitating gait disturbances in different cohorts of patients (such as Parkinson's disease, post-stroke, or other neurological disorders) as it allows patients to be engaged in an immersive and artificial environment, which can be designed to address the particular needs of each individual. This review demonstrates the state of the art in applications of virtual walking techniques and related technologies for gait therapy and rehabilitation of people with movement disorders makes recommendations for future research and discusses the use of VR in the clinic. However, the potential for using these techniques in gait rehabilitation is to provide a more personalized approach by simulate the experience of natural walking, while patients with neurological disorders are maintained localized in the real world. The goal of our work is to investigate how the human nervous system controls movement in health and neurodegenerative disease.

A Novel Viewpoint on the Anticipatory Postural Adjustments During Gait Initiation

Anticipatory postural adjustments (APAs) are the coordinated muscular activities that precede the voluntary movements to counteract the associated postural perturbations. Many studies about gait initiation call APAs those activities that precede the heel-off of the leading foot, thus taking heel-off as the onset of voluntary movement. In particular, leg muscles drive the center of pressure (CoP) both laterally, to shift the body weight over the trailing foot and backward, to create a disequilibrium torque pushing forward the center of mass (CoM). However, since subjects want to propel their body rather than lift their foot, the onset of gait should be the CoM displacement, which starts with the backward CoP shift. If so, the leg muscles driving such a shift are the prime movers. Moreover, since the disequilibrium torque is mechanically equivalent to a forward force acting at the pelvis level, APAs should be required to link the body segments to the pelvis: distributing such concentrated force throughout the body would make all segments move homogeneously. In the aim of testing this hypothesis, we analyzed gait initiation in 15 right-footed healthy subjects, searching for activities in trunk muscles that precede the onset of the backward CoP shift. Subjects stood on a force plate for about 10 s and then started walking at their natural speed. A minimum of 10 trials were collected. A force plate measured the CoP position while wireless probes recorded the electromyographic activities. Recordings ascertained that at gait onset APAs develop in trunk muscles. On the right side, Rectus Abdominis and Obliquus Abdominis were activated in 11 and 13 subjects, respectively, starting on average 33 and 54 ms before the CoP shift; Erector Spinae (ES) at L2 and T3 levels was instead inhibited (9 and 7 subjects, 104 and 120 ms). On the contralateral side, the same muscles showed excitatory APAs (abdominals in 11 and 12 subjects, 27 and 82 ms; ES in 10 and 7 subjects, 75 and 32 ms). The results of this study provide a novel framework for distinguishing postural from voluntary actions, which may be relevant for the diagnosis and rehabilitation of gait disorders.

Repercussions of the Degrees of Hearing Loss and Vestibular Dysfunction on the Static Balance of Children With Sensorineural Hearing Loss

OBJECTIVE

The purpose of this study was to assess the static balance of children with sensorineural hearing loss (SNHL) according to the degrees of SNHL and the function of the vestibular system.

METHODS

This cross-sectional study was conducted in public schools located in Caruaru, Pernambuco state, Brazil, with 130 children (65 with normal hearing and 65 with SNHL as documented by air and bone conduction audiometry) of both sexes between 7 and 11 years old. Static balance was assessed by a stabilometric analysis using a force platform consisting of the circular area of center-of-pressure displacement of the children evaluated in 3 positions: bipedal support with feet together and parallel (PF), tandem feet (TF), and 1 foot (OF), carried out under 2 sensory conditions each, with eyes open and eyes closed. After balance assessments, the children with SNHL received examinations of auditory and vestibular functions-through audiometry and computerized vectoelectronystagmography, respectively-to compose the groups according to degrees of SNHL and vestibular function.

RESULTS

The children with severe and profound SNHL demonstrated more static balance instabilities than the children with normal hearing in 5 positions assessed with eyes open (PF, TF, and OF) and eyes closed (PF and TF). The same phenomenon occurred in children with SNHL and associated vestibular dysfunction in all of the positions assessed with eyes open and eyes closed (PF, TF, and OF).

CONCLUSION

The larger the degree of SNHL, the greater the balance instability of the children. The children with SNHL and associated vestibular dysfunction showed the highest balance instabilities in this study.

IMPACT

Children with larger degrees of SNHL and associated vestibular dysfunction might require prolonged periods to rehabilitate their balance.

Multisensory postural control in adults: Variation in visual, haptic, and proprioceptive inputs

Maintaining balance is fundamentally a multisensory process, with visual, haptic, and proprioceptive information all playing an important role in postural control. The current project examined the interaction between such sensory inputs, manipulating visual (presence versus absence), haptic (presence versus absence of contact with a stable or unstable finger support surface), and proprioceptive (varying stance widths, including shoulder width stance, Chaplin [heels together, feet splayed at approximately 60°] stance, feet together stance, and tandem stance) information. Analyses of mean velocity of the Centre of Pressure (CoP) revealed significant interactions between these factors, with stability gains observed as a function of increasing sensory information (e.g., visual, haptic, visual + haptic), although the nature of these gains was modulated by the proprioceptive information and the reliability of the haptic support surface (i.e., unstable versus stable finger supports). Subsequent analyses on individual difference parameters (e.g., height, leg length, weight, and areas of base of support) revealed that these variables were significantly related to postural measures across experimental conditions. These findings are discussed relative to their implications for multisensory postural control, and with respect to inverted pendulum models of balance. (185 words).

Postural Control and Sleep Quality in Cognitive Dual Tasking in Healthy Young Adults

Although sleep quality disorders can have a negative effect on postural control, studies about this subject are scarce. The aim of this study is to assess the differences in standing posture performance during dual tasking between healthy young adults with a good and poor sleep quality. Thirty-five healthy participants (23.09 ± 3.97 years) performed a postural task (standing posture single task ((ST)) and a dual task (DT): quiet standing while performing a concurrent cognitive task, while the total excursion of the center of pressure (TOTEX CoP), the displacement anterior–posterior (CoP-AP) and medial–lateral (CoP-ML), the mean total velocity displacement of CoP (MVELO CoP) and ellipse sway area (CEA) were measured with a force plate. After assessing the sleep quality with the Pittsburgh Sleep Quality Index, they were divided into two groups (good ((n = 21)) and poor ((n = 14)) sleep quality) to establish comparisons. This study revealed no significant differences in TOTEX CoP, CoP-ML, CoP-AP, MVELO CoP, and CEA among both sleep quality groups. In conclusion, differences in the sleep quality (good or poor sleep quality) among young adults appear not to be a relevant factor in the CoP variation, but the DT versus ST can compromise postural control performance independently of the sleep quality.

Dizziness and localized pain are often concurrent in patients with balance or psychological disorders

Background and aims Symptoms of dizziness and pain are both common complaints and the two symptoms often seem to coincide. When symptoms appear concomitant for sustained periods of time the symptoms might maintain and even exacerbate each other, sometimes leading to psychological distress. In order to evaluate such comorbidity we studied patients referred to a vestibular unit and to a psychiatric outpatient clinic with respectively balance disorders and psychological issues. Methods Consecutive patients referred to a vestibular unit (n = 49) and a psychiatric outpatient clinic (n = 62) answered the Dizziness Handicap Inventory (DHI) questionnaire and a questionnaire detailing occurrence of dizziness and pain. Results The experience of dizziness and pain often coincided within individuals across both clinical populations, especially if the pain was located to the neck/shoulder or the back (p = 0.006). Patients who reported dizziness had significantly more often pain (p = 0.024); in the head (p = 0.002), neck/shoulders (p = 0.003) and feet (p = 0.043). Moreover, patients who reported dizziness stated significantly higher scoring on emotional (p < 0.001) and functional (p < 0.001) DHI sub-scales. Furthermore, patients who reported an accident in their history suffered significantly more often from dizziness (p = 0.039) and pain (p < 0.001); in the head (p < 0.001), neck/shoulders (p < 0.001) and arms (p = 0.045) and they scored higher on the emotional (p = 0.004) and functional (p = 0.002) DHI sub-scales. Conclusions The findings suggest comorbidity to exist between dizziness and neck/shoulder or back pain in patients seeking health care for balance disorders or psychological issues. Patients suffering from dizziness and pain, or with both symptoms, also reported higher emotional and functional strain. Thus, healthcare professionals should consider comorbidity when determining diagnosis and consequent measures. Implications Clinicians need to have a broader "receptive scope" in both history and clinical examinations, and ask for all symptoms. Although the patients in this study visited a vestibular unit respectively a psychological clinic, they commonly reported pain conditions when explicitly asked for this symptom. A multimodal approach is thus to favor, especially when the symptoms persist, for the best clinical management.

Balance and cognitive decline in older adults in the cardiovascular health study

BACKGROUND

Previous studies have demonstrated an association between gait speed and cognitive function. However, the relationship between balance and cognition remains less well explored. This study examined the cross-sectional and longitudinal relationship of balance and cognitive decline in older adults.

METHODS

A cohort of 4,811 adults, aged ≥65 years, participating in the Cardiovascular Health Study was followed for 6 years. Modified Mini-Mental State Examination (3MSE) and Digit Symbol Substitution Test (DSST) were used to measure cognition. Tandem balance measures were used to evaluate balance. Regression models were adjusted for demographics, behavioural and disease factors.

RESULTS

Worse balance was independently associated with worse cognition in cross-sectional analysis. Longitudinally, participants aged ≥76 years with poorer balance had a faster rate of decline after adjustment for co-variates: -0.97 points faster decline in 3MSE per year (95% confidence interval (CI): -1.32, -0.63) compared to the participants with good balance. There was no association of balance and change in 3MSE among adults aged <76 years (P value for balance and age interaction < 0.0001). DSST scores reflected -0.21 (95% CI: -0.37, -0.05) points greater decline when adjusted for co-variates. In Cox proportional hazard models, participants with worse balance had a higher risk of being cognitively impaired over the 6 years of follow-up visits (adjusted HR:1.72, 95% CI: 1.30, 2.29).

CONCLUSIONS

Future studies should evaluate standing balance as a potential screening technique to identify individuals at risk of cognitive decline. Furthermore, a better understanding of the pathophysiological link between balance and cognition may inform strategies to prevent cognitive decline.

Co-morbidities to Vestibular Impairments-Some Concomitant Disorders in Young and Older Adults

Background: Dizziness and pain are common complaints that often appear concomitantly, with or without a causal relationship. However, these symptoms might maintain and exacerbate each other and other co-morbidities. Therefore, adequate rehabilitation may have to include an expanded focus on other deficits and preconditions, especially in older adults and in patients. Objective: To understand how frequently vestibular dysfunction coincided with medical conditions and aging, we studied two categories: Study 1: patients referred to a vestibular unit and Study 2: senior members in a fitness association. Method: Study 1: 49 patients [34 females/15 males; mean age 52 years (SEM 2.0)] seeking health care for balance disorders and vestibular deficits were asked in questionnaires about their perception of dizziness and pain, and emotional and functional strains. Study 2: 101 senior members in a fitness association [91 females/10 males; mean age 75 years (SEM 0.6)], were assessed for vestibular and balance deficits and for any co-morbidities. The participants were monitored for falls for 12 months after the initial assessments. Result: Study 1: Co-morbidity often existed between dizziness and pain (65%). The patients reported high emotional and functional strain related to their dizziness and pain. Patients older than 60 years reported longer durations of pain (p ≤ 0.028) but less emotional strain (p = 0.036), compared to younger patients. Study 2: 84% of the participants had a vestibular impairment, often without noticing any symptoms. Furthermore, 40% reported cardiovascular illnesses, 12% musculoskeletal disorders, and 63% reported other medical conditions. Forty-two percent experienced falls within 1 year after the initial assessments (thereof 42% in the group with vestibular deficits and 38% in the group without vestibular deficits). Conclusion: To enhance and preserve postural control, both in patients with vestibular deficits and in older adults, we suggest an expanded clinical perspective. Hence, we recommend detailed examinations of the vestibular system but simultaneously probing for possible co-morbidities. Since aging often entails deterioration of multimodal processes related to maintained mobility and postural stability, our results add focus on the importance of addressing balance disorders together with additional medical conditions.

Contributions of Vision in Human Postural Control: A Virtual Reality-based Study

During human standing, it has been previously observed that information about the position and frequency of visual surround motion improves balance by reducing sway responses to external disturbances. However, experimental limitations only allowed for independent investigation of such parameters while being incapable of providing a fully immersive experience of a real environment. The aim of this study is to investigate the effect of visual information on dynamic body sway in the human upright stance by presenting perturbations through a virtual reality (VR) system. Moreover, we designed a new perturbation signal based on trapezoidal velocity (TrapV) pulses enabling us to simultaneously examine the effects of amplitude and velocity on balance control. The experiments included four different peak-to-peak amplitudes (1-10 degrees), and three velocities (2-10 degree/sec). The body angle, ankle torques and shank angles were measured and analyzed in response to each perturbation. The results reveal that stimuli with higher amplitudes evoked larger responses, while they were initially increased and reached a peak, then decreased by increasing the motion velocity of visual surround.

Tuning of Standing Postural Responses to Instability and Cost Function

Whole-body movements are performed daily, and humans must constantly take into account the inherent instability of a standing posture. At times these movements may be performed in risky environments and when facing different costs of failure. The aim of the study was to test the hypothesis that in upright stance participants continuously estimate both probability of failure and cost of failure such that their postural responses will be based on these estimates. We designed a snowboard riding simulation experiment where participants were asked to control the position of a moving snowboard within a snow track in a risky environment. Cost functions were provided by modifying the penalty of riding in the area adjacent to the snow track. Uncertainty was modified by changing the gain of postural responses while participants were standing on a rocker board. We demonstrated that participants continually evaluated the environmental cost function and compensated for additional risk with feedback-based postural changes, even when probability of failure was negligible. Results showed also that the participants' estimates of the probability of failure accounted for their own inherent instability. Moreover, participants showed a tendency to overweight large probabilities of failure with more biomechanically constrained standing postures that results in suboptimal estimates of risky environments. Overall, our results suggest that participants tune their standing postural responses by empirically estimating the cost of failure and the uncertainty level in order to minimize the risk of falling when cost is high.

Postural stability of 5-year-old girls and boys with different body heights

Background

Postural stability is one of the determinants of proper body posture and a condition for developing motor abilities in every human being. The measurement of the centre of pressure (COP) location and displacement is the most common technique of postural stability assessment.

Objective

The aim of this study was to assess differences in postural stability depending on sex of 5-year-old children with different body heights.

Methods

A study included 435 healthy children (200 girls and 235 boys) born in 2010 whose parents gave a written consent to their participation in the project. Postural stability was assessed with the use of the dynamographic platform (Zebris FDM 1.8). The assessment of postural stability was based on COP shift parameters (sway path length of COP and average velocity of COP) and COP surface area parameters (area of the ellipse, length of ellipse in the anterior-posterior direction and length of the ellipse in the medial-lateral direction). Body height was measured with Holtein anthropometer and the obtained values were compared with percentile ranks determined by the WHO.

Results

The analysis of the parameters describing postural stability in the examined children revealed dimorphism. For the COP shift parameters and COP surface area parameters, the level of statistical significance was recorded for girls and boys. Girls achieved lower results of these parameters than boys regardless of their body height. In the groups of normal- and tall-statured children, differences between the genders were statistically significant.

Conclusions

The present study characterised sex differences in postural stability of 5-year-old children. Sex-related differences were found during a natural stance for all COP parameters. Girls maintained a two-legged standing position with lower sway velocity and a smaller range of sway than their male counterparts. Normal- and tall-statured girls demonstrated better postural stability significantly more often than boys.

Transcranial Direct Current Stimulation on Parietal Operculum Contralateral to the Moving Limb Does Not Affect the Programming of Intra-Limb Anticipatory Postural Adjustments

Recent data suggest that the parietal operculum acts as an integration center within a multimodal network, originating from different primary sensory and motor cortices and projecting to frontal, parietal and temporal cortical hubs, which in turn govern cognitive and motor functions. Thus, parietal operculum might also play a crucial role in the integrated control of voluntary movement and posture. As a first step to test this hypothesis, the Anticipatory Postural Adjustments (APAs) stabilizing the arm when the index-finger is briskly flexed were recorded, on the preferred side, in three groups of 10 healthy subjects, before, during and after CATHODAL or ANODAL transcranial Direct Current Stimulation (tDCS, 20 min at 2 mA) applied over the contralateral Parietal Operculum (coPO). Results were compared to those obtained in a SHAM group. In agreement with literature, in the SHAM group the activation of the prime mover Flexor Digitorum Superficialis was preceded by an inhibitory APA in Biceps Brachii and Anterior Deltoid, and almost simultaneous to an excitatory APA in Triceps Brachii. The same pattern was observed in both the CATHODAL and ANODAL groups, with no significant tDCS effects on APAs amplitude and timing. Index-finger kinematics were also unchanged. These negative results suggest that the coPO does not disturb the key network governing APAs in index-finger flexion. Since it has been well documented that such APAs share many features with those observed in trunk and limb muscles when performing several other movements, we suggest that coPO may not be crucial to the general APA control.

The cross-sectional relationships between age, standing static balance, and standing dynamic balance reactions in typically developing children

BACKGROUND

Static balance performance is a common metric for evaluating the development of postural control in children. Less is known about the potentially independent development of dynamic balance performance.

RESEARCH QUESTION

How does age relate to static (i.e. postural sway) and dynamic (i.e. stepping thresholds) standing balance performance, and what is the relationship between postural sway and stepping thresholds?

METHODS

Twenty-six typically developing children (12 males, 14 females; 5-12 years of age) were recruited for this cross-sectional study. Static balance performance was quantified as the total path length during a postural sway assessment using a force platform with conditions of eyes open and eyes closed. Dynamic balance performance was quantified using a single-stepping threshold assessment, whereby participants attempted to prevent a step in response to treadmill-induced perturbations in the anterior and posterior directions. Relationships between age and body-size scaled measures of static and dynamic balance performance were assessed using Spearman rank correlations.

RESULTS

There was a weak correlation between age and postural sway (|r_s| < 0.10, p >  0.68), but a moderate-to-strong correlation between age and single-stepping thresholds (r_s > 0.68, p < 0.001). A weak correlation was found between postural sway and single-stepping thresholds (|r_s| < 0.20, p >  0.39).

SIGNIFICANCE

Dynamic, but not static standing balance performance, may improve with typical development between the ages of 5 and 12 years. Static and dynamic balance should be considered as unique constructs when assessed in children.

Effects of forward tilted seating and foot-support on postural adjustments in children with spastic cerebral palsy: An EMG-study

OBJECTIVE

To evaluate the effect of 15° forward (FW) seat inclination and foot-support in children with cerebral palsy (CP) on postural adjustments during reaching.

DESIGN

Observational study repeated-measures design; step two of two-step-project.

SETTING

Laboratory unit within University Hospital and two special education schools.

PARTICIPANTS

19 children (ten unilateral spastic CP (US-CP); nine bilateral spastic CP (BS-CP); Gross Motor Function Classification System levels I-III; 6-12 years old). Participants were able to take part for one one-hour session.

INTERVENTION

Reaching while sitting in four seating conditions (FW or horizontal seat; with or without foot-support) applied in randomized order.

OUTCOME MEASURES

Simultaneously, surface electromyography (EMG) of neck, trunk and arm muscles and kinematics of head and reaching arm (step one of two-step-project) were recorded. Primary outcome parameters were the ability to modulate EMG-amplitudes at baseline and during reaching (phasic muscle activity). Other EMG-parameters were direction-specificity (1st control level), and 2nd level of control parameters: recruitment order, and anticipatory postural activity. Motor behaviour measures: ability to modulate EMG-amplitudes to kinematic characteristics of reaching and head stability.

RESULTS

Only foot-support was associated with increased tonic background EMG-amplitudes and decreased phasic EMG-amplitudes of the trunk extensors in children with US-CP and BS-CP (mixed-models analyses; p-values <0.01). The foot-support effect was also associated with better kinematics of reaching (Spearman's Rho; p-values <0.01).

CONCLUSION

In terms of postural adjustments during forward reaching, foot-support enhanced the children's capacity to modulate trunk extensor activity, which was associated with improved reaching quality. FW-tilting did not affect postural muscle activity.

Optimization of the Effects of Physical Activity on Plantar Sensation and Postural Control With Barefoot Exercises in Institutionalized Older Adults: A Pilot Study

Increasing somatosensory information from the foot by exercising barefoot can potentially optimize the effectiveness of physical exercise interventions on falls prevention in the older adults. This pilot study was then undertaken to explore the effects of increased somatosensory information from the foot by exercising barefoot on balance, gait, and plantar cutaneous sensitivity in institutionalized older adults involved in multimodal exercise intervention. Participants were assigned to three groups: a control group which did not perform any physical exercise and two groups in which they were involved in a multimodal exercise program performed barefoot or shod. Postural, gait, and plantar cutaneous sensitivity parameters were collected. The results showed that the exercise program produced larger effects on balance and plantar cutaneous sensitivity when exercises were performed barefoot, without any noticeable effect on gait. Hence, barefoot exercising could be a relevant means to optimize the fall-prevention exercise programs in institutionalized older adults.

Trunk Control in Children With Ataxic Cerebral Palsy

This study aimed to investigate the clinical characteristics of trunk control in children with ataxic cerebral palsy (CP). We included 15 children with ataxic CP with a mean age of 9.46 years (SD = 1.08 years, 5-17 years) and 15 healthy children with a mean age of 9.06 years (SD = 0.84 years, 5-13 years). While the small sample size and large age range used here were not ideal for generalizability, they were made necessary by the rarity of this clinical sample. We used the Gross Motor Function Classification System Expanded and Revised (GMFCS-E&R) to classify the children's functional levels, and we tested trunk control with the Trunk Control Measurement Scale (TCMS). We then used the Gross Motor Function Measurement-88 (GMFM-88) to assess their gross motor functions. We compared the total and subscale scores of the TCMS in healthy children and children with ataxic CP by using the Mann-Whitney U Test. We also analyzed differences between TCMS scores according to the children's GMFCS levels with the Mann-Whitney U Test and also compared TCMS scores with the GMFM-88 by means of Spearman correlation analysis. Spearman correlation analysis was used to compare the scores of the TCMS with the GMFM-88. Our results showed that healthy children showed significantly higher scores than children with ataxic CP in total and subscale scores of TCMS (p < .05).There was no significant difference between the TCMS scores in children of different GMFCS levels, but the GMFM-88B subscale was significantly correlated with the static sitting balance (r_ho = .568, p < .05) and dynamic sitting balance (r_ho = .547, p < .05) TCMS subscales and with the TCMS total score (r_ho = .590, p < .05). We concluded that trunk control, especially its dynamic aspects, was impaired in children with ataxic CP.

Dual-task effects on postural sway during sit-to-stand movement in children with Down syndrome

BACKGROUND

Cognitive and postural tasks require common cognitive mechanisms, resulting in conflicts when both tasks are simultaneously performed. The presence of neuromotor dysfunctions, such as Down syndrome, may impair coordination processes required to perform dual-tasks. The objective of this study was to investigate the dual-task effects on postural sway during sit-to-stand movements in typical children and children with Down syndrome in a cross-sectional study.

METHODS

Twenty six typical children (10.2 ± 2.4 years) and 21 with Down syndrome (10.3 ± 2.3 years) performed sit-to-stand in the following conditions: (1) simple task; (2) dual-task bimanual activity (DT-Bim): sit-to-stand while carrying a tray using both hands; (3) dual-task unimanual dominant activity (DT-Uni-Dom): sit-to-stand while holding a plastic cup simulating water using the dominant hand; (4) dual-task unimanual non-dominant activity (DT-Uni-Nondom): sit-to-stand movement while holding a plastic cup simulating water. For data analysis, sit-to-stand was divided into three phases: preparation (phase 1), rising (phase 2), and stabilisation (phase 3). The following variables were calculated for each phase: anterior-posterior and medial-lateral amplitude of centre-of-pressure displacement, anterior-posterior and medial-lateral velocity of centre-of-pressure sway and area of centre-of-pressure sway.

RESULTS

Children with Down syndrome showed greater sway than typical children in all sit-to-stand phases. Typical children showed greater anterior-posterior amplitude in phase 2 of sit-to-stand during DT-Uni Nondom compared with DT-Uni Dom. Children with Down syndrome during simple task condition showed greater and faster values sway in phases 2 and 3 of sit-to-stand movement than in DT-Bim activity, DT-Uni Dom activity and DT-Uni Nondom activity. During the condition of DT-Bim activity, these children showed lower anterior-posterior velocity of sway in phase 2 than during DT-Uni Dom activity.

CONCLUSIONS

Children with Down syndrome showed greater postural sway during sit-to-stand than typical children. The addition of a concurrent motor task to sit-to-stand impacted postural sway in different intensities and in different ways across groups. Dual-tasks increased body sway in typical children in the DT-Uni Nondom condition compared with dominant one. In children with Down syndrome, dual-tasks decreased body sway, apparently resulting in a postural strategy of stiffness.

Multisensory factors in postural control: Varieties of visual and haptic effects

Background Previous work on balance control in children and adults highlights the importance of multisensory information. Work in this vein has examined two principal input sources - the role of visual and haptic information on balance. Recent work has explored the impact of a different form of haptic input - object holding - on balance in young infants. Research question This experiment examined the impact of simultaneous visual input and haptic input on balance in children and adults, employing two novel forms of haptic input. Methods Static balance was measured in 3-5 year olds, 7-9 year olds, and young adults, in the presence of all possible combinations of manipulated visual input (eyes open, eyes closed) and haptic input (no touch, object hold, touch an unstable support, touch a stable support). Results Analysis of postural stability (mean velocity) indicated that stability was influenced by visual input, haptic input, and age group. For visual input stability increased in eyes open versus eyes closed conditions. For haptic input, stability systematically increased with increasing levels of fixed haptic input (e.g., no touch, object hold, unstable touch, stable touch). Stability also increased as a function of increasing age group. There were no interactions between the factors. Significance The finding that the two novel forms of haptic input - object hold and touch with an unstable support surface - increased stability relative to no touch input, but not as much as touch with a stable support, indicates that children use haptic information in a self-referential fashion for controlling posture. The failure to observe any interactions between visual and haptic inputs with age suggests that multisensory processing is generally additive across development, and has implications for the occurrence of sensory weighting across developmental epochs.

Attention Is Required to Coordinate Reaching and Postural Stability during Upper Limb Movements Generated While Standing

In the present study we investigated how attention contributes to the interaction between reach planning and execution, and postural control. Reaching movements were generated while standing and were performed either in isolation or in conjunction with a secondary reaction time (RT) task. In addition, to better understand how online movement control is affected by this interaction, the reaching movements could be unexpectedly perturbed medial-laterally. Postural kinetic, arm kinematic and RT, and secondary RT measures were used to characterize the responses. Results indicate task performance worsened when both the reaching and secondary tasks were completed simultaneously. Our results imply the generation of reaching movements while standing requires attentional resources to properly coordinate the interaction between the reaching task and postural control.

Static monocular visual cues can decrease the vestibular-evoked balance response at low frequencies

BACKGROUND

The balance system continually integrates and processes diverse sensorimotor cues to maintain upright posture. Yet, little is known about how monocular visual cues may modulate the vestibular control of standing balance.

RESEARCH QUESTION

To determine how visual cues, specifically monocular vision, modulate the vestibular-evoked myogenic and whole-body balance response.

METHODS

Seventeen (12 female) healthy subjects (age: 24.8 ± 5.3years) were exposed to a random, continuous electrical vestibular stimulation (EVS) signal (±3.5 mA, 0-20 Hz). Subjects stood quietly during four experimental (no vision, non-dominant eye, dominant eye, binocular) conditions. The EVS-medial-lateral ground reaction force (ML GRF) acting on the body and EVS-medial gastrocnemius electromyography (EMG, bilateral) responses were evaluated in the frequency (coherence) and time (cumulant density) domains.

RESULTS

Coherence was increased for no vision compared to binocular, dominant eye, and non-dominant eye visual cues, respectively, with the most pronounced increases occurring at lower frequencies. For cumulant density, the EVS-ML GRF medium-latency peak amplitude was increased 45, 26 and 18% with no vision compared to binocular, dominant eye and non-dominant eye visual cues, respectively (p < .05). The EVS-EMG medium-latency peak amplitude during no vision was greater than binocular (p < .05) for both gastrocnemii, but binocular and dominant eye monocular vision was not different (p > .05). The EVS-ML GRF and EVS-EMG (right medial gastrocnemius) medium-latency peak amplitude was greater for non-dominant eye monocular vision compared to binocular vision (p < .05).

SIGNIFICANCE

Monocular visual cues, at least for the dominant eye, can depress the vestibular-evoked balance response at low frequencies akin to binocular vision with limited differences exhibited between dominant and non-dominant eye.

Trunk control and functionality in children with spastic cerebral palsy

PURPOSE

To investigate the relationship between trunk control in sitting and functionality in children with spastic cerebral palsy (CP).

METHODS

Fifty-eight children with spastic CP were included in the study. Functional abilities were evaluated with the Gross Motor Function Measurement-88 (GMFM-88) and the Pediatric Evaluation of Disability Inventory Functional Skills domain (PEDI-FSD). Trunk control in sitting was tested with the Trunk Control Measurement Scale (TCMS) and the Trunk Impairment Scale (TIS). The scores of the TCMS and TIS were compared with GMFM-88 and PEDI-FSD with Spearman correlation analysis.

RESULTS

The total score of GMFM-88 was significantly correlated with the total score of TCMS (r_ho = 0.90, p < 0.01) and TIS (r_ho = 0.78, p < 0.01). The total score of PEDI-FSD was also significantly correlated with the total score of TCMS (r_ho = 0.76, p < 0.01) and TIS (r_ho = 0.72, p < 0.01).

CONCLUSIONS

The evaluation of trunk control can provide valuable information for functional abilities of children with spastic CP.

Aspectos sensoriais e cognitivos do controle postural

A estabilização postural depende de mecanismos periféricos relativamente simples assim como de mecanismos complexos envolvendo altos níveis de função cognitiva e integração sensório-motora. A teoria de controle baseada em respostas reflexas hierarquicamente organizadas tem cedido lugar a uma visão sistêmica que enfatiza a múltipla organização e interação neural. È tema de discussão a forma de organização das informações sensoriais e do processamento cognitivo e sua relação com a elaboração das estratégias motoras. Buscando responder a estas perguntas este artigo revisa estudos que abordam aspectos biomecânicos, sensoriais e cognitivos do controle postural.

Visual-Vestibular Interaction for Postural Control During Sit-to-Stand: Effects of Aging

During sit-to-stand (STS), the vestibular system is highly stimulated in response to linear acceleration of the head and may play an important role, in addition to vision, for postural control. We examined the effects of aging on visual-vestibular interaction for postural control during STS in 15 young (22.5 ± 1.1 years) and 15 older (73.9 ± 5.3 years) participants. Vestibular information was manipulated using galvanic vestibular stimulation. Vision conditions involved normal (eyes open), suboptimal (blurring goggles), and no (eyes closed) vision. Older participants had significantly greater mediolateral peak-to-peak trunk roll (p = .025) and center of mass displacements (p < .001) than young participants. However, despite having greater mediolateral instability, older participants utilized similar strategies as young participants to overcome sensory perturbations during STS. Overall visual inputs were more dominantly used for mediolateral trunk control during STS than vestibular inputs.

Effect of the severity of manual impairment and hand dominance on anticipatory and compensatory postural adjustments during manual reaching in children with cerebral palsy

AIM

To investigate the role of the severity of manual impairment and of hand dominance on postural sway during anticipatory [APA] and compensatory [CPA] postural adjustments in a seated manual reaching task performed by children with cerebral palsy (CP) and typical children (TC).

METHODS

We tested 26 TC (mean age 9.5 ± 2.1 years) and 29 children with CP (age 9.6 ± 3 years) classified based on manual impairment levels as mild (Manual Ability Classification System [MACS] I; n = 18) or moderate-to-severe (MACS II-III, n = 11). Participants were instructed to reach towards a target using their dominant vs. non-dominant arm while sitting on a force-plate. Center of pressure (CoP) sway was analyzed during APA and CPA.

RESULTS

For all groups, using the non-dominant arm determined greater amplitude and velocity of CoP sway in CPA. Children with moderate-to-severe manual impairment showed greater sway during APA and CPA compared to mild impairment and TC groups.

CONCLUSION

More severe manual impairment resulted in higher sway during the anticipatory and compensatory phases of the reaching task. Using the non-dominant arm resulted in greater compensatory adjustments during reaching.

Effects of Lycra suits in children with cerebral palsy

Lycra garments have recently been used for children with cerebral palsy (CP), with favorable effects on alignment, biomechanics and neuromuscular activity. The aim of the present study is to determine the efficacy of a Lycra suit in improving motor function and static balance in children with CP. Five children with CP wore the Lycra suit for more than 4 h per day for 6 months. They were all assessed at baseline and 6 months after with an evaluation of static balance, using a "seated stabilometry exam", and a motor function assessment, using the Gross Motor Function Measure and Gross Motor function Classification System. The assessment of static balance was performed with and without the suit. Another 5 children with CP performed the same assessments and were used as a control group. An immediate improvement of static balance was observed at baseline, with the first use of the Lycra suit. Further improvement was observed at the 6 month follow up, with a statistical significance for the parameters assessing the antero-posterior axis. Both parents and children also reported functional benefits. Further studies are needed on long-term functional effects in a large cohort of children.

The vestibulomyogenic balance response is elevated following high-intensity lengthening contractions of the lower limb

The purpose was to investigate whether exercise-induced muscle weakness of the plantar and dorsiflexors through high-intensity lengthening contractions increases the vestibulomyogenic balance response. Nine males (∼25 years) participated in three experimental testing days to evaluate the vestibular control of standing balance and neuromuscular function of the plantar and dorsiflexors pre- and post (30 min, and 1 and 7 days) high-intensity lengthening plantar and dorsiflexions. To evaluate the vestibular-evoked balance response, participants stood quietly on a force plate while exposed to continuous, random electrical vestibular stimulation (EVS) for two 90-s trials. Relationships between EVS-antero-posterior (AP) forces and EVS-medial gastrocnemius electromyography (EMG) were estimated in the frequency domain (i.e., coherence). Weakness of the right plantar and dorsiflexors were assessed using maximal voluntary contraction (MVC) torque. The lengthening contractions induced a 13 and 24% reduction in plantar and dorsiflexor MVC torque, respectively (p < 0.05) of the exercised leg, which did not recover by 1 day post. The EVS-EMG coherence increased over a range of frequencies up to 7 days post compared to pre-lengthening contractions. Conversely, EVS-AP forces coherence exhibited limited changes. The greater EVS-EMG coherence post exercise-induced muscle weakness may be a compensatory mechanism to maintain the whole-body vestibular-evoked balance response when muscle strength is reduced.

Early human motor development: From variation to the ability to vary and adapt

This review summarizes early human motor development. From early fetal age motor behavior is based on spontaneous neural activity: activity of networks in the brainstem and spinal cord that is modulated by supraspinal activity. The supraspinal activity, first primarily brought about by the cortical subplate, later by the cortical plate, induces movement variation. Initially, movement variation especially serves exploration; its associated afferent information is primarily used to sculpt the developing nervous system, and less to adapt motor behavior. In the next phase, beginning at function-specific ages, movement variation starts to serve adaptation. In sucking and swallowing, this phase emerges shortly before term age. In speech, gross and fine motor development, it emerges from 3 to 4 months post-term onwards, i.e., when developmental focus in the primary sensory and motor cortices has shifted to the permanent cortical circuitries. With increasing age and increasing trial-and-error exploration, the infant improves its ability to use adaptive and efficicient forms of upright gross motor behavior, manual activities and vocalizations belonging to the native language.

Discriminant ability and criterion validity of the Trunk Impairment Scale for cerebral palsy

Aims: To compare the performance of children with mild and moderate-to-severe cerebral palsy (CP) on the Trunk Impairment Scale (TIS), Gross Motor Function Measure (GMFM), and on center-of-pressure variables; to establish the discriminant ability of these tools to predict severity of motor impairment in CP; and to investigate the criterion validity of the TIS. Methods: Children with mild (n = 18, 11 males, 7 females, mean age = 9.5 ± 2.9 years, Gross Motor Function Classification System I-II) and moderate-to-severe (n = 18, 11 males, 7 females, mean age = 9.2 ± 229, Gross Motor Function Classification System III-IV) CP were tested using the TIS and the GMFM, and during static sitting on force-plate. Results: Children with mild CP showed better trunk (median; 95% confidence interval = 22.5; 21.29-22.59 vs. 13; 11.97-14.8; p < 0.001) and gross motor (60; 57.73-59.3 vs. 40; 38.96-46.25; p < 0.001) scores, and better postural control (lower center of pressure (CoP) displacement [anterior-posterior: (0.42; 0.32-1.11 vs. 0.89; 0.70-1.65; p = 0.022); medial-lateral: (0.42; 0.31-1.08 vs. 0.91; 0.65-1.17; p = 0.044)], and lower area of sway, (0.05; -0.15-0.97 vs. 0.44; 0.23-0.90; p = 0.008) than the moderate-to-severe group. Trunk control and gross motor function explained 81.5% of the variance in the severity of motor condition. Correlations between the TIS and the GMFM were excellent (ρ = 0.944, p < 0.001); correlations between the TIS and CoP variables were low (anterior-posterior displacement: ρ = -0.411, p < 0.05; medial-lateral displacement: ρ = -0.327, p < 0.05); area of sway: ρ = -0.430, p < 0.05; velocity of sway: ρ = -0.308, p < 0.05). Conclusions: The TIS is able to differentiate levels of trunk control across various levels of motor impairments in CP. It is a valid tool to assess trunk control, showing very high concurrent validity with the GMFM sitting dimension. Implications for Rehabilitation Trunk Impairment Scale (TIS) can be used by rehabilitation professionals to differentiate levels of trunk control across levels of motor impairment. TIS showed concurrent validity with Gross Motor Function Measure and should be used to assess trunk control in children with cerebral palsy (CP) in clinical settings. The use of TIS allows a reliable assessment of postural control in children with CP in clinical settings.

Spotlight on postural control in patients with multiple sclerosis

Multiple sclerosis (MS) is a disease that heavily affects postural control, predisposing patients to accidental falls and fall-related injuries, with a relevant burden on their families, health care systems and themselves. Clinical scales aimed to assess balance are easy to administer in daily clinical setting, but suffer from several limitations including their variable execution, subjective judgment in the scoring system, poor performance in identifying patients at higher risk of falls, and statistical concerns mainly related to distribution of their scores. Today we are able to objectively and reliably assess postural control not only with laboratory-grade standard force platform, but also with low-cost systems based on commercial devices that provide acceptable comparability to gold-standard equipment. The sensitivity of measurements derived from force platforms is such that we can detect balance abnormalities even in minimally impaired patients and predict the risk of future accidental falls accurately. By manipulating sensory inputs (dynamic posturography) or by adding a concurrent cognitive task (dual-task paradigm) to the standard postural assessment, we can unmask postural control deficit even in patients at first demyelinating event or in those with a radiologic isolated syndrome. Studies on neuroanatomical correlates support the multifactorial etiology of postural control deficit in MS, with the association with balance impairment being correlated with cerebellum, spinal cord, and highly ordered processing network according to different studies. Postural control deficit can be managed by means of rehabilitation, which is the most important way to improve balance in patients with MS, but there are also suggestions of a beneficial effect of some pharmacologic interventions. On the other hand, it would be useful to pay attention to some drugs that are currently used to manage other symptoms in daily clinical setting because they can further impair postural controls of patients with MS.

Parkinson disease

Parkinson disease (PD) is a complex, multisystem disorder with both neurologic and systemic nonmotor manifestations. It is neurodegenerative in nature in which disordered balance, gait, and falls are universal problems that can be present at initial diagnosis, and which progress over time. Freezing of gait is a particularly debilitating feature of PD that becomes more prevalent over time with disease progression, being present in approximately 7% after 2 years of disease and 28% after 5 years. Approximately 60% of people with PD fall each year, with around 70% of fallers falling recurrently, and some recurrent fallers falling multiple times per week. Many risk factors for falls in people with PD have been identified; these include a history of falls, freezing of gait, and abnormalities in measures of balance, leg muscle strength, mobility, cognition, and fear of falling. Therapies for improving physical function and mobility include levodopa, cholinesterase inhibitors, methylphenidate, deep-brain stimulation, cuing for freezing of gait, and exercise. This chapter reviews the clinical, pathologic, and physiologic correlates of gait disturbance and falls in PD, as well as the evidence for medical and nonmedical interventions.

Balance in children born prematurely currently aged 6–7

Study aim: Premature birth is one of the major problems of obstetrics, leading to numerous complications that are associated with prematurity, for instance balance disorders. The aim of the study was to assess the impact of premature birth on the ability to maintain balance in children commencing their school education. Material and methods: The study included children aged 6-7 years. The study group consisted of 59 children (31 girls and 28 boys, mean age 6.38 ± SD 0.73) born prematurely between 24 and 35 weeks of gestation. The control group consisted of 61 children (28 girls and 33 boys, mean age 6.42 ± 0.58) born at term. The research utilized standardized test tools - one-leg open-eyed and closed-eyed standing test, one-leg jumping test - and an original questionnaire survey. Results: The children born at term achieved better results in the majority of tests. The comparison of girls and boys born pre­maturely and at term showed no statistically significant difference between them in terms of dynamic balance, static balance or total balance control. The comparison of the tests performed on the right and left lower limb in prematurely born children showed no statistically significant differences. Conclusion: Premature birth affects the ability to maintain body balance. The results of the study indicate the need to develop coordination skills that shape body balance in prematurely born children.

Best seating condition in children with spastic cerebral palsy: One type does not fit all

BACKGROUND

The effect of forward-tilting of the seat surface and foot-support in children with spastic cerebral palsy (CP) is debated.

AIM

To assess the effect of forward-tilting of the seat surface and foot-support in children with CP on kinematic head stability and reaching.

METHODS

Nineteen children functioning at Gross Motor Function Classification System levels I-III participated [range 6-12y; ten unilateral spastic CP (US-CP) and nine bilateral spastic CP (BS-CP)]. Kinematic data were recorded of head sway and reaching with the dominant arm in four sitting conditions: a horizontal and a 15° forward (FW) tilted seat surface, each with and without foot-support.

RESULTS

Seating condition did not affect head stability during reaching, but did affect kinematic reaching quality. The major reaching parameters, i.e., the proportion of reaches with one movement unit (MU) and the size of the transport MU, were not affected by foot-support. Forward-tilting had a positive effect on these parameters in children with US-CP, whereas the horizontal condition had this effect in children with BS-CP.

IMPLICATIONS

A 15° forward-tilted seating and foot-support do not affect head stability. Reaching in children with US-CP profits from forward-tilting; in children with BS-CP forward-tilting worsens reaching - effects that are independent of foot-support.