The role of head stabilization in locomotion in children with cerebral palsy

Trend change analysis of postural balance in Parkinson's disease discriminates between medication state

BACKGROUND

Maintaining static balance is relevant and common in everyday life and it depends on a correct intersegmental coordination. A change or reduction in postural capacity has been linked to increased risk of falls. People with Parkinson's disease (pwPD) experience motor symptoms affecting the maintenance of a stable posture. The aim of the study is to understand the intersegmental changes in postural sway and to apply a trend change analysis to uncover different movement strategies between pwPD and healthy adults.

METHODS

In total, 61 healthy participants, 40 young (YO), 21 old participants (OP), and 29 pwPD (13 during medication off, PDoff; 23 during medication on, PDon) were included. Participants stood quietly for 10 s as part of the Short Physical Performance Battery. Inertial measurement units (IMU) at the head, sternum, and lumbar region were used to extract postural parameters and a trend change analysis (TCA) was performed to compare between groups.

OBJECTIVE

This study aims to explore the potential application of TCA for the assessment of postural stability using IMUs, and secondly, to employ this analysis within the context of neurological diseases, specifically Parkinson's disease.

RESULTS

Comparison of sensors locations revealed significant differences between head, sternum and pelvis for almost all parameters and cohorts. When comparing PDon and PDoff, the TCA revealed differences that were not seen by any other parameter.

CONCLUSIONS

While all parameters could differentiate between sensor locations, no group differences could be uncovered except for the TCA that allowed to distinguish between the PD on/off. The potential of the TCA to assess disease progression, response to treatment or even the prodromal PD phase should be explored in future studies.

TRIAL REGISTRATION

The research procedure was approved by the ethical committee of the Medical Faculty of Kiel University (D438/18). The study is registered in the German Clinical Trials Register (DRKS00022998).

Does an outdoor virtual environment projected in a head-mounted display affect balance in healthy young adults?

BACKGROUND

Virtual reality head-mounted display (VR-HMD) is increasingly used for balance evaluation and rehabilitation. However, more studies must be conducted on virtual environments (VE) effects. This study aimed to assess the impact of an outdoor VE projected in a high-quality VR-HMD and of the VR-HMD mass on postural stability, postural control and leaning.

METHODS

This study involved ten healthy young men who performed five 30-s stabilometric trials. Four experimental conditions were randomly performed: eyes open (EO) or eyes closed (EC), with (VR) or without (No VR) VR-HMD. Postural stability (antero-posterior (AP) and medio-lateral (ML) ranges of the center of pressure (CoP), 90% confidence ellipse area), postural control (CoP velocity (global, AP and ML)) and standard deviation of the CoP mean position), and postural leaning (AP/ML CoP mean position) were assessed. The comparisons between EO VR and EO No VR were used to analyze the VE effects and comparisons between EC VR and EC No VR for the VR-HMD mass effects.

RESULTS

Spatiotemporal parameters that characterised postural stability and postural control, except ML velocity (p > 0.05), were significantly influenced by the simulated VE with higher values in EO VR than EO No VR (p < 0.05), but not by the VR-HMD mass. The mean position of the CoP showed no significant differences between conditions.

SIGNIFICANCE

Postural stability and postural control modification due to the VE used in this study revealed that this VE could be interesting for VR-HMD rehabilitation and assessment. VR-HMD is not a factor to be considered for stabilometric analysis.

Differences between Novice and Expert Raters Assessing Trunk Control Using the Trunk Control Measurement Scale Spanish Version (TCMS-S) in Children with Cerebral Palsy

The Trunk Control Measurement Scale (TCMS) is a valid and reliable tool to assess static and dynamic trunk control in cerebral palsy. However, there is no evidence informing about differences between novice and expert raters. A cross-sectional study was conducted with participants between the ages of 6 and 18 years with a CP diagnosis. The TCMS Spanish version (TCMS-S) was administered in-person by an expert rater, and video recordings were taken for later scoring by the expert and three other raters with varying levels of clinical experience. The intraclass correlation coefficient (ICC) was used to evaluate reliability between raters for the total and subscales of the TCMS-S scores. Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC) were also calculated. There was a high level of agreement between expert raters (ICC ≥ 0.93), while novice raters demonstrated good agreement (ICC > 0.72). Additionally, it was observed that novice raters had a slightly higher SEM and MDC than expert raters. The Selective Movement Control subscale exhibited slightly higher SEM and MDC values compared to the TCMS-S total and other subscales, irrespective of the rater's level of expertise. Overall, the study showed that the TCMS-S is a reliable tool for evaluating trunk control in the Spanish pediatric population with cerebral palsy, regardless of the rater's experience level.

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.

Impaired postural control of axial segments in children with cerebral palsy

BACKGROUND

Sensorimotor control of axial segments, which develops during childhood and is not mature until adolescence, is essential for the development of balance control during motor activities. Children with cerebral palsy (CP) have deficits in postural control when standing or walking, including less stabilization of the head and trunk which could affect postural control.

RESEARCH QUESTION

Is dynamic stabilization of axial segments during an unstable sitting task deficient in children with CP compared to typically developing children? Is this deficit correlated with the deficit of postural control during standing?

METHOD

Seventeen children with CP (GMFCS I-II) and 17 typically-developing children from 6 to 12 years old were rated on the Trunk Control Measurement Scale (TCMS). In addition, posturography was evaluated in participants while they maintained their balance in stable sitting, unstable sitting, and quiet standing, under "eyes open" and "eyes closed" conditions. In sitting tasks, the participants had to remain stable while being prevented from using the lower and upper limbs (i.e. to ensure the involvement of axial segments alone).

RESULTS

Children with CP compared to TD children had significantly larger surface area, mean velocity and RMS values of CoP displacements measured during the unstable sitting task and the standing task, under both "eyes open" and "eyes closed" conditions. No significant group effects were observed during the stable sitting task. The TCMS total score was significantly lower, indicating trunk postural deficit, in the CP group than in the TD group and was significantly correlated with postural variables in the sitting and standing tasks.

SIGNIFICANCE

Children with CP indeed have a specific impairment in the postural control of axial segments. Since the postural control of axial segments is important for standing and walking, its impairment should be taken into account in rehabilitation programs for children with CP.

Wearing a head-mounted eye tracker may reduce body sway

This study investigated the effects of wearing a head-mounted eye tracker on upright balance during different visual tasks. Twenty five young adults stood upright on a force plate while performing the visual tasks of fixation, horizontal saccades, and eyes closed, during eighteen trials wearing or not a head-mounted eye tracker. While wearing the eye tracker, participants showed a reduction in mean sway amplitude and velocity of the CoP in the AP and ML directions and more regular CoP fluctuations, in the ML axis in all conditions. Higher mean sway amplitude and velocity of CoP were observed during eyes closed than fixation and saccades. Moreover, horizontal saccades reduced mean sway velocity of CoP compared to fixation. Therefore, wearing the eye tracker minimized the body sway of young adults; however, visual task-related effects on postural stability remained unchanged.

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.

An Acceleration-Based Gait Assessment Method for Children with Cerebral Palsy

With the aim of providing an objective tool for motion disability assessment in clinical diagnosis and rehabilitation therapy of cerebral palsy (CP) patients, an acceleration-based gait assessment method was proposed in this paper. To capture gait information, three inertial measurement units (IMUs) were placed on the lower trunk and thigh, respectively. By comparing differences in the gait acceleration modes between children with CP and healthy subjects, an assessment method based on grey relational analysis and five gait parameters, including Pearson coefficient, variance ratio, the number of extreme points, harmonic ratio and symmetry was established. Twenty-two children with cerebral palsy (7.49 ± 2.86 years old), fourteen healthy adults (24.2 ± 1.55 years old) and ten healthy children (7.03 ± 1.49 years old) participated in the gait data acquisition experiment. The results demonstrated that, compared to healthy subjects, the symptoms and severity of motor dysfunction of CP children could result in abnormality of the gait acceleration modes, and the proposed assessment method was able to effectively evaluate the degree gait abnormality in CP children.

Robotic-assisted gait training improves walking abilities in diplegic children with cerebral palsy

The robotic-assisted gait training therapy (RAGT), based on intensity and repetition of movement, presents beneficial effects on recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effect of this RAGT on the dynamic equilibrium control during walking in children with Cerebral Palsy (CP) by analyzing the different postural strategies of the fullbody (upper/lower body) before and after this RAGT in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon^® - Oxford Metrics). Thirty children with bilateral spastic CP were evaluated using a full-body marker set which allows assessing both the lower and upper limb kinematics. 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 RAGT using the driven gait orthosis Lokomat^®Pediatric (Hocoma) compared to ii) a group of sixteen children without sessions of Lokomat^®Pediatric (Control Group) receiving only daily physiotherapy. Significant improvements are observed between the TG pre- and post-test values of i) the kinematic data of the full-body in the sagittal and frontal planes and ii) the Gross Motor Function Measure test (D and E). This study shows the usefulness of this RAGT mainly in the balance control in gait. Indeed, the Treated Group use new dynamic strategies of gait that are especially characterized by a more appropriate control of the upper body associated with an improvement of the lower limbs kinematics.

Deliberately Light Interpersonal Contact Affects the Control of Head Stability During Walking in Children and Adolescents With Cerebral Palsy

OBJECTIVE

To evaluate the potential of deliberately light interpersonal touch (IPT) for reducing excessive head and trunk sway during self-paced walking in children and adolescents with cerebral palsy (CP).

DESIGN

Quasi-experimental, proof-of-concept study with between-groups comparison.

SETTING

Ambulant care facility, community center.

PARTICIPANTS

Children and adolescents (N=65), consisting of those with CP (spastic and ataxic, n=26; Gross Motor Function Classification System I-III; mean age, 9.8y; 11 girls, 15 boys) and those who were typically developed (TD, n=39; mean age, 10.0y; 23 girls, 16 boys).

INTERVENTIONS

IPT applied by a therapist to locations at the back and the head.

MAIN OUTCOME MEASURES

As primary outcomes, head and trunk sway during self-paced walking were assessed by inertial measurement units. Secondary outcomes were average step length and gait speed.

RESULTS

CP group: apex and occiput IPT reduced head velocity sway compared with thoracic IPT (both P=.04) irrespective of individuals' specific clinical symptoms. TD group: all testing conditions reduced head velocity sway compared with walking alone (all P≤.03), as well as in apex and occiput IPT compared with paired walking (both P≤.02).

CONCLUSIONS

Deliberately light IPT at the apex of the head alters control of head sway in children and adolescents with CP. The effect of IPT varies as a function of contact location and acts differently in TD individuals.

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.

Postural stability in children with hemiplegia estimated for three postural conditions: standing, sitting and kneeling

Postural control deficit is one of the most important problems in children with cerebral palsy (CP). The purpose of the presented study was to compare the effects of body posture asymmetry alone (i.e., in children with mild scoliosis) with the effects of body posture impairment (i.e., in children with hemiplegia) on postural stability. Forty-five outpatients with hemiplegia and 51 children with mild scoliosis were assessed using a posturography device. The examination comprised two parts: (1) analysis of the static load distribution; and (2) a posturographic test (CoP measurements) conducted in three postural conditions: standing, sitting and kneeling. Based on the asymmetry index of the unaffected/affected body sides while standing, the children with hemiplegia were divided into two different postural patterns: a pro-gravitational postural pattern (PGPP) and an anti-gravitational postural pattern (AGPP) (Domagalska-Szopa & Szopa (2013). BioMed Research International, 2013, 462094; (2014). Therapeutics and Clinical Risk Management, 10, 113). The group of children with mild scoliosis, considered as a standard for static body weight distribution, was used as the reference group. The results of present study only partially confirmed that children with hemiplegia have increased postural instability. Strong weight distribution asymmetry was found in children with an AGPP, which induced larger lateral-medial CoP displacements compared with children with scoliosis. In children with hemiplegia, distinguishing between their postural patterns may be useful to improve the guidelines for early therapy children with an AGPP before abnormal patterns of weight-bearing asymmetry are fully established.

Facilitation handlings induce increase in electromyographic activity of muscles involved in head control of cerebral palsy children

This study aimed to investigate the electromyographic (EMG) activation of the main cervical muscles involved in the head control during two postures widely used for the facilitation of head control in children with Cerebral Palsy (CP). A crossover trial involving 31 children with clinical diagnosis of CP and spastic quadriplegia was conducted. Electromyography was used to measure muscular activity in randomized postures. Three positions were at rest: (a) lateral decubitus, (b) ventral decubitus on the floor and (c) ventral decubitus on the wedge. Handlings for facilitating the head control were performed using the hip joint as key point of control in two postures: (a) lateral decubitus and (b) ventral decubitus on wedge. All children underwent standardized handlings, performed by the same researcher with experience in the neurodevelopmental treatment. EMG signal was recorded from muscles involved in the head control (paraspinal and sternocleidomastoid muscles) in sagittal, frontal and transverse planes, at the fourth cervical vertebra (C4), tenth thoracic vertebra (T10) and sternocleidomastoid muscle (SCM) levels. The results showed a significant increase in muscle activation when handling was performed in the lateral decubitus at C4 (P<0.001), T10 (P<0.001) and SCM (P=0.02) levels. A significant higher muscle activation was observed when handling was performed in lateral decubitus when compared to ventral decubitus at C4 level (P<0.001). Handling in ventral decubitus also induced an increase in EMG activation at T10 (P=0.018) and SCM (P=0.004) levels but not at C4 level (P=0.38). In conclusion, handlings performed in both positions may induce the facilitation of head control, as evaluated by the activity of cervical and upper trunk muscles. Handling performed in lateral decubitus may induce a slightly better facilitation of head control. These findings contribute to evidence-based physiotherapy practice for the rehabilitation of severely spastic quadriplegic CP children.

Balance control in gait children with cerebral palsy

This study sought to highlight the balance control process during gait in children with cerebral palsy (CP) by analyzing the different strategies used in order to generate forward motion while maintaining balance. Data were collected using a motion analysis system in order to provide a clinical gait analysis for 16 children with CP and 16 children with typical development. Significant differences between the two groups are observed in terms of kinetic data of the propulsive forces of the center of mass (COM) and of the center of pressure (COP) dynamic trajectory and for locomotor parameters. The imbalance generated by divergent trajectories of COM and COP produce the propulsive forces responsible for human gait initiation. Moreover, we observe in children with CP an "en bloc" postural strategy resulting in increasing divergence between trajectories of COM-COP. This particular strategy of the children with CP is characterized by a greater time duration between the moment of COM-COP trajectory divergence and the moment where the forward propulsive forces became apparent.