Stance posture control in select groups of children with cerebral palsy: deficits in sensory organization and muscular coordination

Motor adaptation to continuous lateral trunk support force during walking improves trunk postural control and walking in children with cerebral palsy: A pilot study

PURPOSE

To determine whether the application of continuous lateral trunk support forces during walking would improve trunk postural control and improve gait performance in children with CP.

MATERIALS AND METHODS

Nineteen children with spastic CP participated in this study (8 boys; mean age 10.6 ± 3.4 years old). Fourteen of them were tested in the following sessions: 1) walking on a treadmill without force for 1-min (baseline), 2) with lateral trunk support force for 7-min (adaptation), and 3) without force for 1-min (post-adaptation). Overground walking pre/post treadmill walking. Five of them were tested using a similar protocol but without trunk support force (i.e., control).

RESULTS

Participants from the experimental group showed enhancement in gait phase dependent muscle activation of rectus abdominis in late adaptation period compared to baseline (P = 0.005), which was retained during the post-adaptation period (P = 0.036), reduced variability of the peak trunk oblique angle during the late post-adaptation period (P = 0.023), and increased overground walking speed after treadmill walking (P = 0.032). Participants from the control group showed modest changes in kinematics and EMG during treadmill and overground walking performance. These results suggest that applying continuous lateral trunk support during walking is likely to induce learning of improved trunk postural control in children with CP, which may partially transfer to overground walking, although we do not have a firm conclusion due to the small sample size in the control group.

Combined translational and rotational perturbations of standing balance reveal contributions of reduced reciprocal inhibition to balance impairments in children with cerebral palsy

Balance impairments are common in cerebral palsy. When balance is perturbed by backward support surface translations, children with cerebral palsy have increased co-activation of the plantar flexors and tibialis anterior muscle as compared to typically developing children. However, it is unclear whether increased muscle co-activation is a compensation strategy to improve balance control or is a consequence of reduced reciprocal inhibition. During translational perturbations, increased joint stiffness due to co-activation might aid balance control by resisting movement of the body with respect to the feet. In contrast, during rotational perturbations, increased joint stiffness will hinder balance control as it couples body to platform rotation. Therefore, we expect increased muscle co-activation in response to rotational perturbations if co-activation is caused by reduced reciprocal inhibition but not if it is merely a compensation strategy. We perturbed standing balance by combined backward translational and toe-up rotational perturbations in 20 children with cerebral palsy and 20 typically developing children. Perturbations induced forward followed by backward movement of the center of mass. We evaluated reactive muscle activity and the relation between center of mass movement and reactive muscle activity using a linear feedback model based on center of mass kinematics. In typically developing children, perturbations induced plantar flexor balance correcting muscle activity followed by tibialis anterior balance correcting muscle activity, which was driven by center of mass movement. In children with cerebral palsy, the switch from plantar flexor to tibialis anterior activity was less pronounced than in typically developing children due to increased muscle co-activation of the plantar flexors and tibialis anterior throughout the response. Our results thus suggest that a reduction in reciprocal inhibition causes muscle co-activation in reactive standing balance in children with cerebral palsy.

Optimization of Postural Control, Balance, and Mobility in Children with Cerebral Palsy: A Randomized Comparative Analysis of Independent and Integrated Effects of Pilates and Plyometrics

The paradigm of comprehensive treatment approaches for children with cerebral palsy has gained traction, prompting clinicians to deliberate between independent and integrated treatment delivery. However, this decision-making process is often hindered by the dearth of empirical evidence available to inform optimal therapeutic strategies. This study, therefore, sought to compare the effects of Pilates-based core strengthening (PsCS), plyometric-based muscle loading (PlyoML), and their combination on postural control, balance, and mobility in children with unilateral cerebral palsy (ULCP). Eighty-one children with ULCP (age: 12-18 years) were randomized to PsCS (n = 27), PlyoML (n = 27), or a combined intervention (n = 27; equated for total sets/repetitions) group. The three interventions were applied twice/week over 12 successive weeks. Postural control (directional and overall limits of stability-LoS), balance, and mobility (Community Balance and Mobility Scale-CB&M; Functional Walking Test-FWT; Timed Up and Down Stair test-TUDS) were assessed pre- and post-intervention. The combined group exhibited greater increases in directional LoS compared to PsCS and PlyoML including the backward (p = 0.006 and 0.033, respectively), forward (p = 0.015 and 0.036, respectively), paretic (p = 0.017 and 0.018, respectively), and non-paretic directions (p = 0.006 and 0.004, respectively)], and this was also the case for overall LoS (p < 0.001 versus PsCS and PlyoML). In addition, the combined group displayed greater improvements compared to the PsCS and PlyoML groups regarding CB&M (p = 0.037 and p = 0.002, respectively), FWT (p = 0.012 and p = 0.038, respectively), and TUDS (p = 0.046 and p = 0.021, respectively). In conclusion, the combined PsCS and PlyoML exercise program promotes considerably greater improvements in postural control, balance, and mobility compared to unimodal training in children with ULCP.

Signs of perceptual disorder during movement were reliably assessed in children with cerebral palsy in Sweden

AIM

The aim of this Swedish study was to evaluate the assessment of clinical signs of perceptual disorder in children with cerebral palsy (CP).

METHODS

Three experienced raters assessed 56 videos of 19 children from 1 to 18 years of age with bilateral spastic CP, which were recorded by colleagues at an Italian hospital. Six signs were evaluated for inter-rater reliability and criterion validity. Clinical applicability was evaluated by assessing inter-rater reliability between 47 Swedish clinicians, who examined 15 of the videos during face-to-face and online education seminars. There were 41 physiotherapists, two occupational therapists and four doctors, with 1-37 years of clinical experience and a median of 10 years.

RESULTS

The experienced raters demonstrated moderate to almost perfect inter-rater reliability (kappa 0.54-0.81) and criterion validity (0.54-0.87) for startle reaction, upper limbs in startle position, averted eye gaze and eye blinking. The clinicians recognised these signs with at least moderate reliability (0.56-0.88). Grimacing and posture freezing were less reliable (0.22-0.35) and valid (0.09-0.50).

CONCLUSION

Four of the six signs of perceptual disorder were reliably recognised by experienced raters and by clinicians after education seminars. Extended education and larger study samples are needed to recognise all the signs.

Trunk postural reactions to the force perturbation intensity and frequency during sitting astride in children with cerebral palsy

The purpose of this study was to examine kinematic and neuromuscular responses of the head and body to pelvis perturbations with different intensities and frequencies during sitting astride in children with CP. Sixteen children with spastic CP (mean age 7.4 ± 2.4 years old) were recruited in this study. A custom designed cable-driven robotic horse was used to apply controlled force perturbations to the pelvis during sitting astride. Each participant was tested in four force intensity conditions (i.e., 10%, 15%, 20%, and 25% of body weight (BW), frequency = 1 Hz), and six force frequency conditions (i.e., 0.5 Hz, 1 Hz, 1.5 Hz, 2 Hz, 2.5 Hz, and 3 Hz, intensity = 20% of BW). Each testing session lasted for one minute with a one-minute rest break inserted between two sessions. Kinematic data of the head, trunk, and legs were recorded using wearable sensors, and EMG signals of neck, trunk, and leg muscles were recorded. Children with CP showed direction-specific trunk and neck muscle activity in response to the pelvis perturbations during sitting astride. Greater EMG activities of trunk and neck muscles were observed for the greater intensities of force perturbations (P < .05). Participants also showed enhanced activation of antagonistic muscles rather than direction-specific trunk and neck muscle activities for the conditions of higher frequency perturbations (P < .05). Children with CP may modulate trunk and neck muscle activities in response to greater changes in intensity of pelvis perturbation during sitting astride. Perturbations with too high frequency may be less effective in inducing direction-specific trunk and neck muscle activities.

Increased muscle responses to balance perturbations in children with cerebral palsy can be explained by increased sensitivity to center of mass movement

BACKGROUND

Balance impairments are common in children with cerebral palsy (CP). Muscle activity during perturbed standing is higher in children with CP than in typically developing (TD) children, but we know surprisingly little about how sensorimotor processes for balance control are altered in CP. Sensorimotor processing refers to how the nervous system translates incoming sensory information about body motion into motor commands to activate muscles. In healthy adults, muscle activity in response to backward support-surface translations during standing can be reconstructed by center of mass (CoM) feedback, i.e., by a linear combination of delayed (due to neural transmission times) CoM displacement, velocity, and acceleration. The level of muscle activity in relation to changes in CoM kinematics, i.e., the feedback gains, provides a metric of the sensitivity of the muscle response to CoM perturbations.

RESEARCH QUESTION

Can CoM feedback explain reactive muscle activity in children with CP, yet with higher feedback gains than in TD children?

METHODS

We perturbed standing balance by backward support-surface translations of different magnitudes in 20 children with CP and 20 age-matched TD children and investigated CoM feedback pathways underlying reactive muscle activity in the triceps surae and tibialis anterior.

RESULTS

Reactive muscle activity could be reconstructed by delayed feedback of CoM kinematics and hence similar sensorimotor pathways might underlie balance control in children with CP and TD children. However, sensitivities of both agonistic and antagonistic muscle activity to CoM displacement and velocity were higher in children with CP than in TD children. The increased sensitivity of balance correcting responses to CoM movement might explain the stiffer kinematic response, i.e., smaller CoM movement, observed in children with CP.

SIGNIFICANCE

The sensorimotor model used here provided unique insights into how CP affects neural processing underlying balance control. Sensorimotor sensitivities might be a useful metric to diagnose balance impairments.

Review of electromyography onset detection methods for real-time control of robotic exoskeletons

BACKGROUND

Electromyography (EMG) is a classical technique used to record electrical activity associated with muscle contraction and is widely applied in Biomechanics, Biomedical Engineering, Neuroscience and Rehabilitation Robotics. Determining muscle activation onset timing, which can be used to infer movement intention and trigger prostheses and robotic exoskeletons, is still a big challenge. The main goal of this paper was to perform a review of the state-of-the-art of EMG onset detection methods. Moreover, we compared the performance of the most commonly used methods on experimental EMG data.

METHODS

A total of 156 papers published until March 2022 were included in the review. The papers were analyzed in terms of application domain, pre-processing method and EMG onset detection method. The three most commonly used methods [Single (ST), Double (DT) and Adaptive Threshold (AT)] were applied offline on experimental intramuscular and surface EMG signals obtained during contractions of ankle and knee joint muscles.

RESULTS

Threshold-based methods are still the most commonly used to detect EMG onset. Compared to ST and AT, DT required more processing time and, therefore, increased onset timing detection, when applied on experimental data. The accuracy of these three methods was high (maximum error detection rate of 7.3%), demonstrating their ability to automatically detect the onset of muscle activity. Recently, other studies have tested different methods (especially Machine Learning based) to determine muscle activation onset offline, reporting promising results.

CONCLUSIONS

This study organized and classified the existing EMG onset detection methods to create consensus towards a possible standardized method for EMG onset detection, which would also allow more reproducibility across studies. The three most commonly used methods (ST, DT and AT) proved to be accurate, while ST and AT were faster in terms of EMG onset detection time, especially when applied on intramuscular EMG data. These are important features towards movement intention identification, especially in real-time applications. Machine Learning methods have received increased attention as an alternative to detect muscle activation onset. However, although several methods have shown their capability offline, more research is required to address their full potential towards real-time applications, namely to infer movement intention.

Investigation of the Relationship between Sensory-Processing Skills and Motor Functions in Children with Cerebral Palsy

The main purpose of this study is to examine the relationship between sensory-processing skills and gross motor functions, bimanual motor functions, and balance in children with cerebral palsy (CP). A total of 47 patients between the ages of 3 and 10, diagnosed with CP, who received or applied for treatment in our physical therapy and rehabilitation unit were included in the study. Sensory profiling (SP), assisting hand assessment (AHA), the Gross Motor Function Measure-66 (GMFM-66), and the Pediatric Berg Balance Scale (PBBS) were used in the evaluation of the children with CP who participated in the study. The Gross Motor Function Classification System (GMFCS) was used to classify the children based on functional abilities and limitations, and the Manual Ability Classification System (MACS) was used to classify the children based on manual dexterity. The SP parameters were compared with AHA, GMFM-66, and PBBS results, and with GMFCS and MACS levels. Statistically significant relationships were found between AHA and SP, PBBS, and SP and between GMFM-66 and SP (p < 0.05). Our study shows that there are some disorders in sensory processing in children with CP. We think that sensory evaluations should be included in the CP rehabilitation program.

Acupuncture and Tuina Treatment for Gross Motor Function in Children with Spastic Cerebral Palsy: A Monocentric Clinical Study

Objective

Cerebral palsy (CP) is a condition characterized by abnormal pronunciation, posture, and movement, particularly spastic CP, which involves Gross motor dysfunction due to increased muscle tone and stiffness. This monocentric clinical study aims to evaluate the effectiveness of acupuncture and tuina (AT) in improving gross motor function and alleviating associated symptoms in children diagnosed with spastic CP.

Methods

A total of 83 eligible patients received AT treatment, while 85 patients received conventional rehabilitation treatment. Both groups underwent a 12-week treatment period following the research protocol. Pre- and post-treatment assessments included the Modified Ashworth Muscle Tension Scale (MAS), Gross Motor Function Measure (GMFM-D and GMFM-E), 6-min walking distance measurement (6MWD), and Modified Children's Functional Independence Rating Scale (WeeFIM).

Results

After 12 weeks of treatment, when compared with baseline, the scores of MAS in both AT group and control group are decreased (p<0.01, p<0.01), the scores of GMFM-D, GMFME, 6MWD, WeeFIM in both group are increased (p<0.01 in all indicators). When compared with control group, AT group had significantly lower MAS scores compared to the control group (p<0.01), indicating reduced muscle tension. Moreover, AT group showed significantly higher scores in GMFM-D, GMFM-E, 6MWD, and WeeFIM compared to the control group (p<0.01 in all indicators), indicating improved gross motor function and functional independence. The study also revealed an inverse correlation between the children's age and treatment efficacy (r= -0.496, p<0.01 in AT group, r=-0.540, p<0.01 in control group), highlighting the importance of early intervention in the management of CP in children.

Conclusion

These findings suggest that AT may effectively enhance gross motor function and alleviate associated symptoms in children diagnosed with spastic CP. Moreover, early initiation of treatment is crucial to maximize therapeutic efficacy in children with spastic CP.

Trial Registration

Chinese Clinical Trial Registry, ChiCTR2200059823. Registered on 12 May 2022.

Responses to Sensory Events in Daily Life in Children with Cerebral Palsy from a Parent Reported Perspective and in a Swedish Context

The motor disorders of cerebral palsy (CP) are often accompanied by sensory disturbances, but knowledge of their relationship to motor functioning is sparse. This study explored responses to sensory events in relation to spastic subtype and motor functioning in children with CP. Parents of 60 children with CP (unilateral: 18, bilateral: 42) with GMFCS levels I:29, II:13, III:15 and IV:3 of mean age 12.3 years (3.7 SD) participated. The parents (n = 55) rated their children´s responses with the norm-referenced questionnaire Child Sensory Profile-2© (CSP-2©), Swedish version, incorporating nine sections and four sensory processing patterns/quadrants, and replied (n = 57) to two additional questions. On the CSP-2©, thirty (55%) of the children were reported to have responses "much more than others" (>2 SD) in one or more of the sections and/or quadrants and 22 (40%) in the section of Body Position, overrepresented by the children with bilateral CP. The additional questions revealed that a greater proportion of children at GMFCS levels III-IV compared to level I frequently were requested to sit/stand up straight (14/17 versus 6/26, p < 0.001) and were sound sensitive at a younger age (14/17 versus 10/26, p = 0.005). The findings of this study highlight the sensory aspects of motor functioning in children with spastic CP.

Exploring Temporospatial Gait Asymmetry, Dynamic Balance, and Locomotor Capacity After a 12-Week Split-Belt Treadmill Training in Adolescents with Unilateral Cerebral Palsy: A Randomized Clinical Study

AIM

To investigate the effects of a 12-week split-belt treadmill walking (Sb-TW) practice using an error augmentation strategy on temporospatial gait asymmetries, dynamic balance, and locomotor capacity in adolescents with unilateral cerebral palsy (ULCP).

METHODS

Fifty-two adolescents with ULCP (age: 10-16 years) were randomized into either the Sb-TW group (n = 26; underwent repeated Sb-TW practice, with exaggeration of the initial step-length asymmetry, three times/week, for 12 sequential weeks) or control group (n = 26; received equivalent dosages of traditional single-belt treadmill training). Step-length and swing-time asymmetries, directional (LoSdirectional) and overall (LoSoverall) limits of stability, and locomotor capacity [6-minute walk test (6-MWT), Timed Up and Down Stair test (TUDS), and 10-m Shuttle Run Test (10mSRT)] were assessed pre- and post-intervention.

RESULTS

The Sb-TW group demonstrated more favorable changes in step-length asymmetry (p < .001, η2partial = 0.27), LoSdirectional [affected side direction (p = .033, η2partial = 0.09), forward direction (p = .004, η2partial = 0.16), and backward direction (p = .01, η2partial = 0.12)], and LoSoverall (p < .001, η2partial = 0.31) than the control group. Also, the Sb-TW group showed significantly higher locomotor capacity [6-MWT (p < .001, η2partial = 0.38), TUDS (p = .032, η2partial = 0.09), 10mSRT (p = .021, η2partial = 0.10)] as compared to the control group.

CONCLUSION

The Sb-TW-induced adaptations can be capitalized on for remediating spatial gait asymmetry, dynamic balance deficits, and impaired locomotor performance in adolescents with ULCP.

Brain structural and functional connectivity and network organization in cerebral palsy: A scoping review

AIM

To explore altered structural and functional connectivity and network organization in cerebral palsy (CP), by clinical CP subtype (unilateral spastic, bilateral spastic, dyskinetic, and ataxic CP).

METHOD

PubMed and Embase databases were systematically searched. Extracted data included clinical characteristics, analyses, outcome measures, and results.

RESULTS

Sixty-five studies were included, of which 50 investigated structural connectivity, and 20 investigated functional connectivity using functional magnetic resonance imaging (14 studies) or electroencephalography (six studies). Five of the 50 studies of structural connectivity and one of 14 of functional connectivity investigated whole-brain network organization. Most studies included patients with unilateral spastic CP; none included ataxic CP.

INTERPRETATION

Differences in structural and functional connectivity were observed between investigated clinical CP subtypes and typically developing individuals on a wide variety of measures, including efferent, afferent, interhemispheric, and intrahemispheric connections. Directions for future research include extending knowledge in underrepresented CP subtypes and methodologies, evaluating the prognostic potential of specific connectivity and network measures in neonates, and understanding therapeutic effects on brain connectivity.

Functional progressive resistance exercise versus eccentric muscle control in children with hemiplegia: a randomized controlled trial

Background

Historically, strength exercise in children with CP is not recommended, because it may develop spasticity, which results in difficulty with walking. But, recently increasing studies and systemic reviews have reported that strength exercise can promote muscle strength in children with CP with no negative impact on spasticity. The study is aiming to compare the effect of functional resistance exercise and functional eccentric training on dynamic balance and functional ability in children with hemiplegia. For this purpose, forty participating children diagnosed with spastic hemiplegia were included and their ages ranged from 6 to 13 years. They were randomly allocated into two groups: functional resistance exercise (group I) or eccentric muscle control exercise (group II). The training was conducted three times a week for 6 weeks for both groups. Each group received one of the interventions in addition to designed physical therapy programs. Functional ability and dynamic balance were measured before and after 6 weeks of the intervention by gross motor function measure and functional reach test.

Results

Comparison between the two groups before treatment revealed no significant difference in all values of functional ability and dynamic balance. But comparison after treatment in values showed significant improvement in both groups with greater improvements in favor of group I (p < 0.01).

Conclusion

Adding both functional resistance exercise and eccentric muscle control exercise is beneficial for improving functional ability and dynamic balance with more recommendation for adding functional resistance exercise that showed more significant improvement than eccentric muscle control in children with hemiplegia.

Age-related changes in the activation timing of postural muscles to the prime mover muscle for bilateral arm flexion during standing

Background

We aimed to obtain the standard values of age-related changes in the activation timing of postural muscles to the prime mover muscle (anterior deltoid [AD]) for bilateral arm flexion during standing.

Methods

The study participants were 276 children (aged 3–14 years) and 32 adults (aged 20–26 years). In response to a visual stimulus, participants raised both arms from a fully extended position as quickly as possible, stopped their arms voluntarily at a horizontal level at the shoulder, and maintained that position for 2 s. Ten test trials were performed. By using surface electromyography, the duration from the burst onset of the postural muscles to that of AD was measured as the starting time of the postural muscles (rectus abdominis [RA], erector spinae [ES], rectus femoris [RF], biceps femoris [BF], tibialis anterior [TA], gastrocnemius medialis [GcM], and soleus [SOL]). The starting time was presented as a negative value when the burst onset of the postural muscles preceded that of AD, which was defined as the preceding activation. A positive value for the starting time was defined as delayed activation.

Results

In adults, the burst onsets of ES and BF significantly preceded that of AD. In ES, the starting time preceded the onset of AD in those aged ≥ 5–6 years; no difference with adults was found at age 13–14 years. On the other hand, in BF, significant delayed activation was found at ages 3–4 to 11–12 years. While the starting time decreased with age, no significant preceding activation similar to adults was found, even at age 13–14 years. In TA, no significant difference with the onset of AD was found at age 3–6 years, and significant delayed activation was found at age ≥ 7–8 years. Significant delayed activation in GcM, SOL, RA, and RF was observed in all age groups, and no age-related changes were observed in children.

Conclusion

These findings could provide standard values from childhood to adolescence for age-related changes in anticipatory postural muscle activity during voluntary movement while standing and contribute to applications in the fields of sports and rehabilitation.

Reliability and validity of the Swaymeter for measuring the trunk control in children with spastic cerebral palsy

AIMS

To examine the reliability and validity of a simple device, the Swaymeter, for measuring trunk control in children with CP.

METHODS

Twenty children with spastic CP participated in this study. Trunk sway was measured while quietly sitting for 30s. Children lean forward or backward as far as possible for measuring dynamic balance range. Test-retest reliability was conducted. The concurrent and construct validity of the Swaymeter was assessed by comparison to the motion capture system and gross motor function measure (GMFM).

RESULTS

The reliability of the Swaymeter was moderate to excellent in measuring trunk sway and dynamic balance range (ICCs = 0.696-0.948). Concurrent validity showed good results (r = 0.818-0.997) and construct validity of dynamic balance in anterior direction showed moderate to high correlation with the GMFM (r = 0.599-0.849).

CONCLUSION

Assessment of trunk control in a sitting position using the Swaymeter in this study was valid and reliable in children with CP.

Changes in intersegmental stability during gait in patients with spastic cerebral palsy

BACKGROUND

Dysfunction in peripheral and neural structure with spastic cerebral palsy (CP) causes impaired performance and stability of various behaviors. Recent progress of quantification methods for the stability properties, which is based on the uncontrolled manifold hypothesis, has been applied to various neurological disorders. A prior study revealed that the ability for purposeful regulation of stability properties is weakened with CP during finger and hand actions. Successive regulation of stability properties is crucial for human locomotion; therefore, it is imperative to quantify the changes in the intersegmental coordination as to the stable performance in CP individuals during gait.

RESEARCH QUESTION

We hypothesized that (1) Spastic CP group will show smaller step length and gait velocity with larger variability, and (2) Spastic CP group will show no changes in average stability indices for both the COM and head position stabilization, while the smaller difference between stable and unstable posture during the gait cycle.

METHODS

Whole-body kinematic data during walking were collected from CP and control subjects. Step length, velocity, and coefficient of variation (CV) were calculated as spatiotemporal parameters. We quantified the intersegmental stability index in time-series during gait for the stabilization of the whole-body COM and head position.

RESULTS

The CP subjects showed smaller step length and velocity with larger CV than the controls. However, the CP group showed a significantly less difference in the stability indices between the single- and double-limb support phases as compared to the controls for both the COM and head position stabilization.

SIGNIFICANCE

Present study is the first to document the quantification of changing intersegmental stability in the spastic CP during locomotion. The dysfunction of intentional modulation of stability properties in CP individuals may be a more common problem, which is not limited to a specific body effector.

Sex and age influence on postural sway during sit-to-stand movement in children and adolescents: Cross-sectional study

We investigated the influence of sex and age in postural sway during sit-to-stand (STS) in children and adolescents of 5-15 years. We evaluated sway during STS in 86 typical participants. STS was divided into three phases: preparation, rising, and stabilization. We calculated for each phase: area, anterior-posterior, and medial-lateral velocity of center-of-pressure sway. We applied a stepwise multiple linear regression model to determine if age and sex might be predictors of postural sway during STS. Only age was associated with sway, accounting for between 6.5% and 14.6% of the variability in sway during STS. The age of the subject influences postural sway during STS, but in a small amount. This variable should be taken into account as a variable of control in the assessment of dynamic postural control. Moreover, postural stability during STS was not associated with the sex of the participants.

Postural mechanisms in moderate-to-severe cerebral palsy

People with moderate-to-severe cerebral palsy (CP) have the greatest need for postural control research yet are usually excluded from research due to deficits in sitting ability. We use a support system that allows us to quantify and model postural mechanisms in nonambulatory children with CP. A continuous external bench tilt stimulus was used to evoke trunk postural responses in seven sitting children with CP (ages 2.5 to 13 yr) in several test sessions. Eight healthy adults were also included. Postural sway was analyzed with root mean square (RMS) sway and RMS sway velocity, along with frequency response functions (FRF, gain and phase) and coherence functions across two different stimulus amplitudes. A feedback model (including sensorimotor noise, passive, reflexive, and sensory integration mechanisms) was developed to hypothesize how postural control mechanisms are organized and function. Experimental results showed large RMS sway, FRF gains, and variability compared with adults. Modeling suggested that many subjects with CP adopted "simple" control with major contributions from a passive and reflexive mechanism and only a small contribution from active sensory integration. In contrast, mature trunk postural control includes major contributions from sensory integration and sensory reweighting. Relative to their body size, subjects with CP showed significantly lower damping, three to five times larger corrective torque, and much higher sensorimotor noise compared with the healthy mature system. Results are the first characterization of trunk postural responses and the first attempt at system identification in moderate-to-severe CP, an important step toward developing and evaluating more targeted interventions.NEW & NOTEWORTHY Cerebral palsy (CP) is the most common cause of motor disability in children. People with moderate-to-severe CP are typically nonambulatory and have major impairments in trunk postural control. We present the first systems identification study to investigate postural responses to external stimulus in this population and hypothesize at how the atypical postural control system functions with use of a feedback model. People with moderate-to-severe CP may use a simple control system with significant sensorimotor noise.

Evaluating validity of the Kids-Balance Evaluation Systems Test (Kids-BESTest) Clinical Test of Sensory Integration of Balance (CTSIB) criteria to categorise stance postural control of ambulant children with CP

PURPOSE

Evaluate the validity of the Clinical Test of Sensory Integration of Balance (CTSIB) scored using Kids-Balance Evaluation Systems Test (Kids-BESTest) criteria compared to laboratory measures of postural control.

METHOD

Participants were 58 children, 7-18 years, 17 with ambulant cerebral palsy (CP) (GMFCS I-II), and 41 typically developing (TD). Postural control in standing was assessed using CTSIB items firm and foam surfaces, eyes open (EO) then closed (EC). Face validity was evaluated comparing clinical Kids-BESTest scores between groups. Correlating force plate centre-of-pressure (CoP) data and clinical scores allowed evaluation of concurrent and content validity.

RESULTS

Face validity: TD children scored higher for all CTSIB conditions when compared to children with CP. Concurrent validity: the agreement between clinical and CoP derived scores was poor to excellent (Firm-EO = 76%, Firm-EC = 76%, Foam-EO = 59%, Foam-EC = 94%). Clinical scores of "2-unstable" and "3-stable" were not distinguished reliably by force plate measures. Content validity: significant correlations were found between clinical scores and CoP data for the two intermediate conditions (Firm-EC: r_s -0.40 to -0.72; Foam-EO: r_s -0.12 to -0.50), but not the easier (Firm-EO: r_s -0.41 to -0.36) or harder conditions (Foam-EC: r_s -0.25 to -0.27).

CONCLUSION

Face validity of Kids-BESTest CTSIB criteria was supported. Content and concurrent validity were partially supported. Improved Kids-BESTest scoring terms were recommended to describe postural characteristics of "2-unstable."IMPLICATIONS FOR REHABILITATIONFace validity of the Kids-BESTest criteria for the CTSIB was confirmed.The Kids-BESTest criteria for the CTSIB can identify children with atypical postural control.Concurrent validity and content validity were partially supported, since children with CP resorted to a range of different balance strategies when "unstable."To improve CTSIB Kids-BESTest criteria, new terms were recommended to better describe postural characteristics of "2-unstable."

The effect of dual-task conditions on gait and balance performance in children with cerebral palsy: A systematic review and meta-analysis of observational studies

Dual-task conditions are commonly experienced in daily routines. The aim of the present systematic review is to investigate the effect of dual-task conditions on gait and balance performance in children with cerebral palsy (CP) and to perform meta-analyses where applicable. Five databases, "ProQuest", "PubMed", "OTSeeker", "Scopus", and "PEDro" from the incipient date of databases up to Aug 24, 2020 were searched for studies focusing on the effects of dual-task conditions on gait and balance performance in children with CP. After removing irrelevant articles and applying inclusion and exclusion criteria, nine articles were included in the present systematic review and meta-analysis. The results of the meta-analysis showed that walking speed was slower during dual-task conditions compared to single-task conditions in children with CP (WMD = -0.29 m/s, 95% CI = -0.34, -0.24, P ≤ 0.001) and walking speed decreased in children with CP during dual-task conditions in comparison with the typical development (TD) control group (WMD = -0.19 m/s, 95% CI = -0.23 to -0.15, P ≤ 0.001). The results of subgroup analysis based on the type of task indicated that adding concurrent tasks to walking degrades walking speed under varied dual-task conditions. Additionally, theoretical synthesis of the literature demonstrated that other gait and balance variables are changed by performing cognitive and motor secondary tasks differently. Although these changes may be compensatory strategies to retain their stability, there was not sufficient evidence to reach a firm conclusion. Research gaps and recommendations for future studies are discussed.

Bilateral symmetry in leg and joint stiffness in children with spastic hemiplegic cerebral palsy during gait

Deviations are often identified at individual joints in the gait analysis of patients with cerebral palsy. Previous gait studies on hemiplegic cerebral palsy (HCP) have focused mainly on deviations of the affected side. The current study aimed to quantify and compare the joint and leg stiffness, the contributions of skeletal and muscular components, and the associated joint angles and moments of the affected and nonaffected lower limbs during level walking in children with spastic HCP. A total of 12 children with spastic HCP and 12 healthy controls walked at a self-selected speed in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, midstance, terminal stance, and preswing. The altered joint kinematics and kinetics in the nonaffected limb in the HCP group appeared to be mainly a compensatory strategy to minimize the bilateral asymmetry in leg stiffness during the double-limb support phase and joint stiffness during the entire stance phase. The current results suggest that therapeutic planning and decision-making for children with HCP should consider not only the mechanics of the affected side but also the control of the nonaffected side.

Effect of Functional Progressive Resistance Exercise on Lower Extremity Structure, Muscle Tone, Dynamic Balance and Functional Ability in Children with Spastic Cerebral Palsy

The purpose of this study was to investigate the effects of functional progressive resistance exercise (FPRE) on muscle tone, dynamic balance and functional ability in children with spastic cerebral palsy. Twenty-five subjects were randomized into two groups: the FPRE group (n = 13) and the control group (n = 12). The experimental group participated in an FPRE program for 30 min per day, three times per week for six weeks. Knee extensor strength, rehabilitative ultrasound imaging (RUSI), muscle tone, dynamic balance, and functional ability was evaluated. The results showed statistically significant time × group interaction effects on the dominant side for knee extensor strength and cross-sectional area (CSA) in RUSI (p < 0.05). On both sides for thickness of the quadriceps (TQ) in RUSI, muscle tone and dynamic balance were statistically significant time × group interaction effects (p < 0.05). Additionally, knee extensor strength, CSA, TQ in RUS, muscle tone, dynamic balance and gross motor function measure (GMFM) in functional ability were significantly increased between pre- and post-intervention within the FPRE group (p < 0.05). The results suggest that FPRE is both feasible and beneficial for improving muscle tone, dynamic balance and functional ability in children with spastic cerebral palsy.

Anteroposterior balance reactions in children with spastic cerebral palsy

AIM

To compare anterior and posterior standing balance reactions, as measured by single-stepping thresholds, in children with and without spastic cerebral palsy (CP).

METHOD

Seventeen ambulatory children with spastic CP (eight males, nine females) and 28 typically developing children (13 males, 15 females; age range 5-12y, mean [SD] 9y 2mo [2y 3mo]), were included in this cross-sectional, observational study. Balance reaction skill was quantified as anterior and posterior single-stepping thresholds, or the treadmill-induced perturbations that consistently elicited a step in that direction. In order to understand the underlying mechanisms of between-group differences in stepping thresholds, dynamic stability was quantified using the minimum margin of stability. Ankle muscle activation latency, magnitude, and co-contraction were assessed with surface electromyography.

RESULTS

We observed an age and group interaction for anterior thresholds (p=0.001, partial η² =0.24). At older (≈11y; p<0.001, partial η² =0.48), but not younger (≈7y; p=0.33, partial η² =0.02) ages, typically developing children had larger anterior thresholds than those with CP. In response to near-threshold anterior perturbations, older typically developing children recovered from more instability than their peers with CP (p=0.004, partial η² =0.18). Older children had no between-group differences in ankle muscle activity. No between-group differences were observed in posterior thresholds.

INTERPRETATION

The effects of CP on balance reactions are age- and direction-specific. Older typically developing children are more able or willing to withhold a step when unstable.

WHAT THIS PAPER ADDS

Children with spastic cerebral palsy have age- and direction-specific balance-reaction impairments. Lower anterior stepping thresholds were observed in older, but not younger children. Older typically developing children withheld a forward step at higher levels of instability. No between-group differences were seen in posterior stepping thresholds.

Brain Stiffness Relates to Dynamic Balance Reactions in Children With Cerebral Palsy

Cerebral palsy is a neurodevelopmental movement disorder that affects coordination and balance. Therapeutic treatments for balance deficiencies in this population primarily focus on the musculoskeletal system, whereas the neural basis of balance impairment is often overlooked. Magnetic resonance elastography (MRE) is an emerging technique that has the ability to sensitively assess microstructural brain health through in vivo measurements of neural tissue stiffness. Using magnetic resonance elastography, we have previously measured significantly softer grey matter in children with cerebral palsy as compared with typically developing children. To further allow magnetic resonance elastography to be a clinically useful tool in rehabilitation, we aim to understand how brain stiffness in children with cerebral palsy is related to dynamic balance reaction performance as measured through anterior and posterior single-stepping thresholds, defined as the standing perturbation magnitudes that elicit anterior or posterior recovery steps. We found that global brain stiffness is significantly correlated with posterior stepping thresholds (P = .024) such that higher brain stiffness was related to better balance recovery. We further identified specific regions of the brain where stiffness was correlated with stepping thresholds, including the precentral and postcentral gyri, the precuneus and cuneus, and the superior temporal gyrus. Identifying brain regions affected in cerebral palsy and related to balance impairment can help inform rehabilitation strategies targeting neuroplasticity to improve motor function.

Complicated Muscle-Bone Interactions in Children with Cerebral Palsy

PURPOSE OF REVIEW

The goal of this review is to highlight the deficits in muscle and bone in children with cerebral palsy (CP), discuss the muscle-bone relationship in the CP population, and identify muscle-based intervention strategies that may stimulate an improvement in their bone development.

RECENT FINDINGS

The latest research suggests that muscle and bone are both severely underdeveloped and weak in children with CP, even in ambulatory children with mild forms of the disorder. The small and low-performing muscles and limited participation in physical activity are likely the major contributors to the poor bone development in children with CP. However, the muscle-bone relationship may be complicated by other factors, such as a high degree of fat and collagen infiltration of muscle, atypical muscle activation, and muscle spasticity. Muscle-based interventions, such as resistance training, vibration, and nutritional supplementation, have the potential to improve bone development in children with CP, especially if they are initiated before puberty. Studies are needed to identify the muscle-related factors with the greatest influence on bone development in children with CP. Identifying treatment strategies that capitalize on the relationship between muscle and bone, while also improving balance, coordination, and physical activity participation, is an important step toward increasing bone strength and minimizing fractures in children with CP.

The Rehabilitative Effects of Virtual Reality Games on Balance Performance among Children with Cerebral Palsy: A Meta-Analysis of Randomized Controlled Trials

This research aims to evaluate the effect of virtual reality (VR) games on balance recovery of children with cerebral palsy (CP) by quantitatively synthesizing the existing literature, and to further determine the impact of VR game intervention (the duration of each intervention, intervention frequency, intervention cycle, and total intervention time) on the balance recovery of children with CP. To this end, relevant literature up until 3 August 2019 was retrieved from Chinese databases (CNKI and Wanfang Data) and the databases in other languages (Web of Science, Pubmed, EBSCOhost, Informit, Scopus, Science Direct, and ProQuest), and bias analysis was conducted with the PEDro scale in this research. Randomized controlled trials (RCTs) were selected and underwent meta-analysis, and combined effect size was calculated with a random effects model. The results showed that VR games may improve the balance of children with CP (Hedge’s g = 0.29; 95% CI 0.10–0.48), and no significant influence of the intervention on balance of children with CP was shown in the subgroup analysis. In conclusion, VR games played a positive role in the improvement of balance of children with CP, but these results should be viewed with caution owing to current methodological defects (difference in measurement, heterogeneity of control groups, intervention combined with other treatments, etc.).

From movement to action: a new framework for cerebral palsy

The interpretation of cerebral palsy (CP) is closely linked to points of view that are no longer acceptable: 1) the idea that it is primarily a motor problem (posture and movement disorder); 2) the idea that it is only a central (cerebral) pathology; 3) the idea that it is a non-progressive disease (fixed encephalopathy). Actually, the problems that contribute to producing the CP clinical picture are several and complex. First of all, building of the action, starting from subject motivation, through motor imagery and subsequent project elaboration. Sequentially, executive planning, disorder often hidden under the most remarkable alteration of motor patterns and muscle tone. Finally, realization, conditioned by the idea that the locomotor apparatus is only and always the victim of an incapable central nervous system. Little known and very neglected perceptive components can contribute to compromising subject motor control. The influences that primitive changes of musculoskeletal system, often depending on site, nature, size and time of the lesion, exert on the possible choices of the central nervous system are often overlooked. Peripheral structures can in fact modify considerably the expression of palsy (understood as the form of adaptive functions) primitively. At least six different sources of error can be identified in the cerebral palsied child. For a rehabilitative intervention with greater possibilities of effectiveness, it is necessary to recognize and evaluate each of them. Especially as regards the prevention of secondary deformities, the responsibility attributed to physiotherapy must be re-evaluated.

Effects of sensory manipulations on the dynamical structure of center-of-pressure trajectories of children with cerebral palsy during sitting

AIM

To investigate the effects of manipulating visual information and the compliance of the support surface on the area of sway and dynamical trajectories of center-of-pressure (CoP) in children with CP and children with typical development during static sitting.

METHODS

32 typical children, 14 children with mild CP and 12 with moderate-to-severe CP were tested for CoP sway during static sitting under four sensory conditions: (1) eyes open on a rigid surface; (2) eyes closed on a rigid surface; (3) eyes open on foam; (4) eyes closed on foam.

RESULTS

Children with moderate-to-severe CP showed greater regularity and local stability of dynamical CoP trajectories and lower complexity in their motor patterns than typical children and children with mild CP. Moreover, removing vision and sitting on a compliant surface reduced the regularity of CoP trajectories.

CONCLUSION

Children with CP were able to adjust the structure and complexity of their postural control responses to sensory challenges, although the structure of their postural responses was poorer than in typical children.

Comparison of simultaneous static standing balance data on a pressure mat and force plate in typical children and in children with cerebral palsy

BACKGROUND

Balance testing is an important component in treatment planning and outcome assessment for children with Cerebral Palsy (CP). Objective measurement for static standing balance is typically conducted in motion labs utilizing force plates; however, a plantar pressure mat may prove to be a viable alternative for this type of balance assessment.

METHODS

This study examined static standing balance simultaneously on a force plate and a plantar pressure mat in 30 typically developing (TD) and 30 children with CP to determine if valid measures of static standing balance could be obtained in children with CP using a pressure mat.

RESULTS

Examination of the data provided evidence that reliable and valid measures of static standing balance can be produced with a plantar pressure mat for both groups. Five variables out of the 21 variables examined were found to be reliable and valid on both devices (pressure mat and force plate) for both subgroups (TD and CP). The variables medial/lateral (ML) average radial displacement, range moved-ML, anterior/posterior average velocity, ellipse area, and area per second were found to have high test-retest reliability (ICC > .6) and possess discriminant validity between the subgroups (TD vs. CP). Additionally, the ellipse area and area per second variables also had the ability to discriminate between GMFCS levels. A normative center of pressure (CoP) balance data set using all 21 variables was also established for typically developing children for both devices (pressure mat and force plate) within this study.

SIGNIFICANCE

The ability to utilize a portable plantar pressure mat for quick and reliable standing balance measurement allows for expanded ability to capture objective data in a variety of settings thereby increasing opportunity for outcomes analysis.

Stochastic resonance stimulation improves balance in children with cerebral palsy: a case control study

Background

Stochastic Resonance (SR) Stimulation has been used to enhance balance in populations with sensory deficits by improving the detection and transmission of afferent information. Despite the potential promise of SR in improving postural control, its use in individuals with cerebral palsy (CP) is novel. The objective of this study was to investigate the immediate effects of electrical SR stimulation when applied in the ankle muscles and ligaments on postural stability in children with CP and their typically developing (TD) peers.

Methods

Ten children with spastic diplegia (GMFCS level I- III) and ten age-matched TD children participated in this study. For each participant the SR sensory threshold was determined. Then, five different SR intensity levels (no stimulation, 25, 50, 75, and 90% of sensory threshold) were used to identify the optimal SR intensity for each subject. The optimal SR and no stimulation condition were tested while children stood on top of 2 force plates with their eyes open and closed. To assess balance, the center of pressure velocity (COPV) in anteroposterior (A/P) and medial-lateral (M/L) direction, 95% COP confidence ellipse area (COPA), and A/P and M/L root mean square (RMS) measures were computed and compared.

Results

For the CP group, SR significantly decreased COPV in A/P direction, and COPA measures compared to the no stimulation condition for the eyes open condition. In the eyes closed condition, SR significantly decreased COPV only in M/L direction. Children with CP demonstrated greater reduction in all the COP measures but the RMS in M/L direction during the eyes open condition compared to their TD peers. The only significant difference between groups in the eyes closed condition was in the COPV in M/L direction.

Conclusions

SR electrical stimulation may be an effective stimulation approach for decreasing postural sway and has the potential to be used as a therapeutic tool to improve balance. Applying subject-specific SR stimulation intensities is recommended to maximize balance improvements. Overall, balance rehabilitation interventions in CP might be more effective if sensory facilitation methods, like SR, are utilized by the clinicians.

Trial registration

ClinicalTrials.gov identifier NCT02456376; 28 May 2015 (Retrospectively registered); https://clinicaltrials.gov/ct2/show/NCT02456376.

Children with moderate to severe cerebral palsy may not benefit from stochastic vibration when developing independent sitting

PURPOSE

Determine sitting postural control changes for children with cerebral palsy (CP), using a perceptual-motor intervention and the same intervention plus stochastic vibration through the sitting surface.

METHODS

Two groups of children with moderate or severe CP participated in the 12 week interventions. The primary outcome measure was center of pressure data from which linear and nonlinear variables were extracted and the gross motor function measure (GMFM).

RESULTS

There were no significant main effects of intervention or time or an interaction. Both treatment groups increased the Lyapunov exponent values in the medial-lateral direction three months after the start of treatment as well as their GMFM scores in comparison with baseline.

CONCLUSIONS

The stochastic vibration did not seem to advance the development of sitting postural control in children between the ages of 2 and 6 years. However, perceptual-motor intervention was found beneficial in advancing sitting behavior.

Effects of Suit-Orthosis on Postural Adjustments During Seated Reaching Task in Children With Cerebral Palsy

AIM

To investigate suit-orthosis effects on postural sway during anticipatory and compensatory postural adjustments (APA and CPA, respectively) in a seated reaching task performed by children with cerebral palsy (CP).

METHODS

Twenty-nine children were divided according to Manual Ability Classification System (MACS) I and II-III. Participants were instructed to reach forward toward an object both in a no-suit condition and in a suit-orthosis condition.

RESULTS

Using the suit-orthosis, children at MACS II-III decreased velocity of center-of-pressure (CoP) sway during APA, whereas children at MACS I increased the anterior-posterior CoP displacement during CPA.

CONCLUSION

Suit-orthosis improved postural stability in children at MACS II-III during APA. The suit may assist with arm function control during postural sway when preparing to reach for objects.

CLINICAL IMPLICATIONS

Suit-orthoses in therapy should be individually prescribed considering the intended activity and person's motor impairment.

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.

Estimation of Foot Plantar Center of Pressure Trajectories with Low-Cost Instrumented Insoles Using an Individual-Specific Nonlinear Model

Postural control is a complex skill based on the interaction of dynamic sensorimotor processes, and can be challenging for people with deficits in sensory functions. The foot plantar center of pressure (COP) has often been used for quantitative assessment of postural control. Previously, the foot plantar COP was mainly measured by force plates or complicated and expensive insole-based measurement systems. Although some low-cost instrumented insoles have been developed, their ability to accurately estimate the foot plantar COP trajectory was not robust. In this study, a novel individual-specific nonlinear model was proposed to estimate the foot plantar COP trajectories with an instrumented insole based on low-cost force sensitive resistors (FSRs). The model coefficients were determined by a least square error approximation algorithm. Model validation was carried out by comparing the estimated COP data with the reference data in a variety of postural control assessment tasks. We also compared our data with the COP trajectories estimated by the previously well accepted weighted mean approach. Comparing with the reference measurements, the average root mean square errors of the COP trajectories of both feet were 2.23 mm (±0.64) (left foot) and 2.72 mm (±0.83) (right foot) along the medial–lateral direction, and 9.17 mm (±1.98) (left foot) and 11.19 mm (±2.98) (right foot) along the anterior–posterior direction. The results are superior to those reported in previous relevant studies, and demonstrate that our proposed approach can be used for accurate foot plantar COP trajectory estimation. This study could provide an inexpensive solution to fall risk assessment in home settings or community healthcare center for the elderly. It has the potential to help prevent future falls in the elderly.

Effect of robotic-assisted gait rehabilitation on dynamic equilibrium control in the gait of children with cerebral palsy

Due to the intensity and repetition of movement, roboticassisted gait training therapy could have a beneficial effect on the recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effects of robotic-assisted gait rehabilitation in gait of children with Cerebral Palsy (CP). We analyzed the different strategies before and after this rehabilitation which was used in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon® - Oxford Metrics, Oxford, UK). The children were divided into two groups in such a way as to obtain a randomized controlled population: i) a group of fourteen children (Treated Group) underwent 20 sessions of roboticassisted gait training therapy using the driven gait orthosis Lokomat®Pediatric (Hocoma AG, Volketswil, Switzerland) compared to ii) a group of sixteen children without sessions of Lokomat®Pediatric (Control Group). Significant differences are observed for the TG between the preand post-test values of the locomotor parameters and of the kinetic data of the propulsive forces of the Center of Mass (COM) and of the Center of Pressure (COP) dynamic trajectory. This first study, although performed on a limited number of patients, shows the usefulness of this robotic gait rehabilitation mainly in the balance control in gait. Indeed after this rehabilitation, these children improve their gait that is especially characterized by a more appropriate time lag between the time instant of COM-COP trajectory divergence and the time instant when the forward propulsive forces became apparent.

Cerebral palsy

Cerebral palsy (CP) is a lifespan motor disorder arising from damage to the developing brain before or shortly after birth. People with CP may experience problems with muscle coordination and difficulties with the organization and processing of sensory information. Functional mobility is impaired and commonly influenced by spasticity and musculoskeletal system problems such as contractures or bony torsion. Around 60% of individuals with CP are able to walk independently or with aids when entering adulthood. However, many adults with CP experience increasing balance and mobility dysfunction associated with premature aging. Falls and reduced falls efficacy are commonly experienced, with associated physical and psychosocial consequences. There is evidence that ambulant adults with CP may be able to enhance their functional balance and mobility as a result of an individualized exercise program of sufficient duration and intensity. However, whether such programs result in a reduction in falls is unknown. Given the high number of falls with injury experienced by this population, attention to fall risk factors and provision of basic fall prevention strategies are warranted.

Skilled Movements Require Non-apoptotic Bax/Bak Pathway-Mediated Corticospinal Circuit Reorganization

Early postnatal mammals, including human babies, can perform only basic motor tasks. The acquisition of skilled behaviors occurs later, requiring anatomical changes in neural circuitry to support the development of coordinated activation or suppression of functionally related muscle groups. How this circuit reorganization occurs during postnatal development remains poorly understood. Here we explore the connectivity between corticospinal (CS) neurons in the motor cortex and muscles in mice. Using trans-synaptic viral and electrophysiological assays, we identify the early postnatal reorganization of CS circuitry for antagonistic muscle pairs. We further show that this synaptic rearrangement requires the activity-dependent, non-apoptotic Bax/Bak-caspase signaling cascade. Adult Bax/Bak mutant mice exhibit aberrant co-activation of antagonistic muscle pairs and skilled grasping deficits but normal reaching and retrieval behaviors. Our findings reveal key cellular and molecular mechanisms driving postnatal motor circuit reorganization and the resulting impacts on muscle activation patterns and the execution of skilled movements.

Recognizing the Common Origins of Dystonia and the Development of Human Movement: A Manifesto of Unmet Needs in Isolated Childhood Dystonias

Dystonia in childhood may be severely disabling and often unremitting and unrecognized. Considered a rare disorder, dystonic symptoms in childhood are pervasive in many conditions including disorders of developmental delay, cerebral palsy (CP), autism, neurometabolic, neuroinflammatory, and neurogenetic disorders. Collectively, there is a need to recognize the role of early postures and movements which characterize phases of normal fetal, infant, and child development as a backdrop to the many facets of dystonia in early childhood neurological disorders and to be aware of the developmental context of dystonic symptoms. The role of cocontraction is explored throughout infancy, childhood, young adulthood, and in the elderly. Under-recognition of pervasive dystonic disorders of childhood, including within CP is reviewed. Original descriptions of CP by Gowers are reviewed and contemporary physiological demonstrations are used to illustrate support for an interpretation of the tonic labyrinthine response as a manifestation of dystonia. Early recognition and molecular diagnosis of childhood dystonia where possible are desirable for appropriate clinical stratification and future precision medicine and functional neurosurgery where appropriate. A developmental neurobiological perspective could also be useful in exploring new clinical strategies for adult-onset dystonia disorders focusing on environmental and molecular interactions and systems behaviors.

Dependence of Gait Deviation on Weight-Bearing Asymmetry and Postural Instability in Children with Unilateral Cerebral Palsy

Postural control deficits have been suggested to be a major component of gait disorders in children with cerebral palsy. The purpose of this study was to investigate the relationship between postural stability and treadmill walking, in children with unilateral cerebral palsy, by defining dependence between the posturographic weight-bearing distribution and center of pressure (CoP) sway during quiet standing with Gillette Gait Index and the 16 distinct gait parameters that composed the Gillette Gait Index. Forty-five children with unilateral cerebral palsy from 7–12 years of age were included in this study. A posturographic procedure and 3-dimensional instrumented gait analysis was developed. In general, across the entire tested group, the significant correlations concerned only the asymmetry of the weight bearing and a few of the distinct gait parameters that compose the Gillette Gait Index; moreover, correlation coefficients were low. The division of subjects into two clinical subgroups: children that exhibited a tendency to overload (1) and to underload (2) the affected body side, modified the results of the explored relationships. Our findings revealed that the difficulties experienced by children with hemiplegia while controlled in a standing position result from tendency to excessively or insufficiently load the affected lower limbs, and thus establishes a direct relationship with inadequate affected peak ankle DF in both stance and swing gait phases. Given the presented relationship between postural instability and deviation of the particular gait parameters in children with unilateral cerebral palsy, a follow-up study will be needed to determine the therapeutic approaches that will be most effective in promoting increased improvement in gait pattern, as well as the static and dynamic balance in standing.

Effects of severity of gross motor disability on anticipatory postural adjustments while standing in individuals with bilateral spastic cerebral palsy

BACKGROUND

Although individuals with bilateral spastic cerebral palsy (BSCP) exhibit several deficits in anticipatory postural adjustments (APAs) while standing, effects of severity of motor disability on their APAs are unclear.

AIMS

To determine whether individuals with BSCP exhibit severity-dependent deficits in APAs.

METHODS AND PROCEDURES

Seven individuals with level II BSCP (BSCP-II group) and seven with level III BSCP (BSCP-III group) according to the Gross Motor Function Classification System and seven healthy controls lifted a load under two different load conditions.

OUTCOMES AND RESULTS

Anticipatory activities of the erector spinae (ES), medial hamstring (MH), and gastrocnemius (GCM) were smaller in the two BSCP groups than in the control group. Although the anticipatory GCM activity was similar between the BSCP groups, the ES and MH activities were larger in the BSCP-II group than in the BSCP-III group. In the BSCP-II group, an increase in anticipatory activity with an increase in load was observed in the MH, but not in the GCM. In the BSCP-III group, load-related modulation was not found in the MH or GCM.

CONCLUSIONS AND IMPLICATIONS

The present findings suggest that in individuals with BSCP with severe motor disability, APA deficits extend to more proximal parts of the body.

Changes in Standing and Walking Performance Under Dual-Task Conditions Across the Lifespan

Simultaneous performance of a postural and a concurrent task is rather unproblematic as long as the postural task is executed in an automatic way. However, in situations where postural control requires more central processing, cognitive resources may be exceeded by the addition of an attentionally demanding task. This may lead to interference between the two tasks, manifested in a decreased performance in one or both tasks (dual-task costs). Owing to changes in attentional demands of postural tasks as well as processing capacities across the lifespan, it might be assumed that dual-task costs are particularly pronounced in children and older adults probably leading to a U-shaped pattern for dual-task costs as a function of age. However, these changes in the ability of dual-tasking posture from childhood to old age have not yet been systematically reviewed. Therefore, Web of Science and PubMed databases were searched for studies comparing dual-task performance with one task being standing or walking in healthy groups of young adults and either children or older adults. Seventy-nine studies met inclusion criteria. For older adults, the expected increase in dual-task costs could be confirmed. In contrast, in children there was only feeble evidence for a trend towards enlarged dual-task costs. More good-quality studies comparing dual-task ability in children, young, and, ideally, also older adults within the same paradigm are needed to draw unambiguous conclusions about lifespan development of dual-task performance in postural tasks. There is evidence that, in older adults, dual-task performance can be improved by training. For the other age groups, these effects have yet to be investigated.

Increased Adaptation Rates and Reduction in Trial-by-Trial Variability in Subjects with Cerebral Palsy Following a Multi-session Locomotor Adaptation Training

Cerebral Palsy (CP) results from an insult to the developing brain and is associated with deficits in locomotor and manual skills and in sensorimotor adaptation. We hypothesized that the poor sensorimotor adaptation in persons with CP is related to their high execution variability and does not reflect a general impairment in adaptation learning. We studied the interaction between performance variability and adaptation deficits using a multi-session locomotor adaptation design in persons with CP. Six adolescents with diplegic CP were exposed, during a period of 15 weeks, to a repeated split-belt treadmill perturbation spread over 30 sessions and were tested again 6 months after the end of training. Compared to age-matched healthy controls, subjects with CP showed poor adaptation and high execution variability in the first exposure to the perturbation. Following training they showed marked reduction in execution variability and an increase in learning rates. The reduction in variability and the improvement in adaptation were highly correlated in the CP group and were retained 6 months after training. Interestingly, despite reducing their variability in the washout phase, subjects with CP did not improve learning rates during washout phases that were introduced only four times during the experiment. Our results suggest that locomotor adaptation in subjects with CP is related to their execution variability. Nevertheless, while variability reduction is generalized to other locomotor contexts, the development of savings requires both reduction in execution variability and multiple exposures to the perturbation.

The Effects of Selective Dorsal Rhizotomy on Balance and Symmetry of Gait in Children with Cerebral Palsy

Aim

Cerebral palsy (CP) is associated with dysfunction of the upper motor neuron and results in balance problems and asymmetry during locomotion. Selective dorsal rhizotomy (SDR) is a surgical procedure that results in reduced afferent neuromotor signals from the lower extremities with the aim of improving gait. Its influence on balance and symmetry has not been assessed. The aim of this prospective cohort study was to evaluate the impact of SDR on balance and symmetry during walking.

Methods

18 children (10 girls, 8 boys; age 6 years (y) 3 months (m), SD 1y 8m) with bilateral spastic CP and Gross Motor Function Classification System levels I to II underwent gait analysis before and 6 to 12 months after SDR. Results were compared to 11 typically developing children (TDC; 6 girls, 5 boys; age 6y 6m, SD 1y 11m). To analyse balance, sway velocity, radial displacement and frequency were calculated. Symmetry ratios were calculated for balance measures and spatio-temporal parameters during walking.

Results

Most spatio-temporal parameters of gait, as well as all parameters of balance, improved significantly after SDR. Preoperative values of symmetry did not vary considerably between CP and TDC group and significant postoperative improvement did not occur.

Interpretation

The reduction of afferent signalling through SDR improves gait by reducing balance problems rather than enhancing movement symmetry.

Upper extremity function: What's posture got to do with it?

This perspective paper reviews the linkage between developing postural control and upper extremity function. We suggest updated principles for guiding clinical practice, based on current views from motor learning, motor development, and motor control research. Using three clinical examples, we illustrate principles focusing on the use of variability, the importance of errors in learning movement, task specific exploration and practice, and the critical timing necessary to build skill of the upper extremity in a variety of postures. These principles differ from historic approaches in therapeutic exercise, which treated posture as a separate system and a precursor for extremity skill building. We maintain that current movement science supports the tight interaction of posture and upper extremity function through developmental time and in real time, such that one system cannot be considered separate from the other. Specific suggestions for clinical practice flow from the guiding principles outlined in this paper.

Cerebral palsy

Cerebral palsy is the most common cause of childhood-onset, lifelong physical disability in most countries, affecting about 1 in 500 neonates with an estimated prevalence of 17 million people worldwide. Cerebral palsy is not a disease entity in the traditional sense but a clinical description of children who share features of a non-progressive brain injury or lesion acquired during the antenatal, perinatal or early postnatal period. The clinical manifestations of cerebral palsy vary greatly in the type of movement disorder, the degree of functional ability and limitation and the affected parts of the body. There is currently no cure, but progress is being made in both the prevention and the amelioration of the brain injury. For example, administration of magnesium sulfate during premature labour and cooling of high-risk infants can reduce the rate and severity of cerebral palsy. Although the disorder affects individuals throughout their lifetime, most cerebral palsy research efforts and management strategies currently focus on the needs of children. Clinical management of children with cerebral palsy is directed towards maximizing function and participation in activities and minimizing the effects of the factors that can make the condition worse, such as epilepsy, feeding challenges, hip dislocation and scoliosis. These management strategies include enhancing neurological function during early development; managing medical co-morbidities, weakness and hypertonia; using rehabilitation technologies to enhance motor function; and preventing secondary musculoskeletal problems. Meeting the needs of people with cerebral palsy in resource-poor settings is particularly challenging.