Kinematics and postural muscular activity during continuous oscillating platform movement in children and adolescents

© 2018 Springer-Verlag GmbH Germany, part of Springer Nature. The aims of this study were to (1) characterize anticipatory and reactive postural strategies in typically developing (TD) children and adolescents; (2) determine if TD youth shift from reactive to anticipatory mechanisms based on knowledge of platform movement; and (3) determine whether TD youth further modify postural strategies when additional information about the perturbation is provided. Sixteen typically developing youth aged 7–17 years stood with eyes open on a movable platform that progressively translated anteroposteriorly (20 cm peak-to-peak) through four speeds (0.1, 0.25, 0.5, and 0.61 Hz). Participants performed two trials each of experimenter-triggered and self-triggered perturbations. Postural muscle activity (1000 Hz) of the tibialis anterior, gastrocnemius, quadriceps and hamstrings and 3D whole body kinematics (100 Hz) were recorded. The Anchoring Index and marker-pair trajectory cross-correlations were calculated as indications of body stabilization. The number of steps taken to regain balance/avoid falling were counted. Transition states and steady states were analyzed separately. Generally, the higher frequencies resulted in more steps being taken, lower correlations coupled with greater temporal lags between marker trajectories, and postural muscle activity similar to older adults. The provision of self-triggered perturbations allowed participants to make the appropriate changes to their balance by use of anticipatory postural control mechanisms

Kinematics and postural muscular activity during continuous oscillating platform movement in children and adolescents with cerebral palsy

Background: Reactive and anticipatory postural activity has been described in single discrete perturbations in youth with cerebral palsy (CP) but not in continuous perturbation situations. Research Question: We sought to determine how the ability to control postural responses (as reflected in the number of steps taken, postural muscle activity, and marker-pair trajectory cross-correlations) compares between typically developing (TD) youth and age-matched youth with CP when exposed to various frequencies of continuous platform oscillation. We also sought to determine if youth with CP could further modify postural activity based on knowledge of platform movement. Methods: Eleven youth with CP and sixteen TD youth aged 7–17 years stood with eyes open on a movable platform progressively translated antero-posteriorly through four speeds in experimenter-triggered and self-triggered perturbations. Postural muscle activity and 3D kinematics were recorded. The Anchoring Index and marker-pair trajectories were used to quantify body stabilization strategies. Transition states and steady states were analysed. Mann Whitney-U tests analysed between-group differences at each frequency. Results: At lower frequencies (0.1 and 0.25 Hz) youth with CP behaved like age-matched TD controls. At higher frequencies (0.5 and 0.61 Hz), youth with CP took a greater number of steps, had a preference for stabilizing their head on the trunk, had low marker-pair correlations with high temporal lag, and showed increased tonic activity compared to their TD peers. Significance: Higher frequency platform movements proved more difficult for youth with CP, however, like TD youth, they shifted from reactive to anticipatory mechanisms when the platform frequency remained constant by taking advantage of knowledge of platform movement. When given control over perturbation onset, further evidence of anticipatory mechanisms was observed following the transition to a new oscillation frequency

The Effects of a 5-Day Virtual-Reality Based Exercise Program on Kinematics and Postural Muscle Activity in Youth with Cerebral Palsy

Aims: To determine the effects of a 5-day virtual reality (VR)-based intervention on anticipatory and reactive mechanisms of postural control in children and adolescents with cerebral palsy (CP). Methods: Eleven youth with CP (GMFCS levels I and II), ages 7–17, were allocated to intervention (N = 5) and control (N = 6) groups. Both groups attended balance assessment sessions 1 week apart. Participants in the intervention group received 1-hour one-on-one physiotherapist-supervised VR balance games for 5 consecutive days between assessments. For balance assessments, participants stood erect with eyes open on a movable platform that translated progressively through four speeds in the anterior/posterior direction. Participants performed two trials each of experimenter-triggered and self-triggered perturbations. Postural muscle activity and kinematics were recorded. The Anchoring Index and body segment cross-correlations were calculated as an indication of body stabilization, and the number of steps taken to regain balance/avoid falling were counted. Mann–Whitney U tests for between group differences in change scores were undertaken with an accepted significance level of 0.01. Results: No consistent differences in change scores were identified between groups. Conclusions: There was no effect of a 5-day VR-based intervention on postural control mechanisms used in response to oscillating platform perturbations. Subsequent studies will further tailor VR interventions to patients’ functional balance needs

Anal Cancer debuting as Cancer of Unknown Primary

Anal cancer usually presents with a visible or palpable tumour. In this case we describe a 54-year old man diagnosed with Cancer of Unknown Primary (CUP) with a single inguinal node as the only finding. Thorough examination failed to identify any primary tumour. The patient was treated with lymph node dissection and not until nearly two years after initial diagnosis, was the primary tumour found, and the patient was diagnosed with anal cancer. The patient was treated with chemoradiotherapy and 45 months after initial diagnosis there is still no sign of relapse. This case illustrates, that anal cancer can metastasise before the primary tumour is detectable. Furthermore, it demonstrates the necessity of thorough clinical follow-up after treatment of CUP since the primary tumour was found later. Finally this is a case of a long-term survivor following treatment for metastatic inguinal lymph nodes from an initially unknown primary cancer

Active Video Gaming for Children with Cerebral Palsy: Does a Clinic-Based Virtual Reality Component Offer an Additive Benefit? A Pilot Study

Aims: To compare changes in gross motor skills and functional mobility between ambulatory children with cerebral palsy who underwent a 1-week clinic-based virtual reality intervention (VR) followed by a 6-week, therapist-monitored home active video gaming (AVG) program and children who completed only the 6-week home AVG program. Methods: Pilot non-randomized controlled trial. Five children received 1 hour of VR training for 5 days followed by a 6-week home AVG program, supervised online by a physical therapist. Six children completed only the 6-week home AVG program. The Gross Motor Function Measure Challenge Module (GMFM-CM) and Six Minute Walk Test (6MWT) evaluated change. Results: There were no significant differences between groups. The home AVG-only group demonstrated a statistically and clinically significant improvement in GMFM-CM scores following the 6-week AVG intervention (median difference 4.5 points, interquartile range [IQR] 4.75, p = 0.042). The VR + AVG group demonstrated a statistically and clinically significant decrease in 6MWT distance following the intervention (median decrease 68.2 m, IQR 39.7 m, p = 0.043). All 6MWT scores returned to baseline at 2 months post-intervention. Conclusion: Neither intervention improved outcomes in this small sample. Online mechanisms to support therapist-child communication for exercise progression were insufficient to individualize exercise challenge

Protocol: Health, social care and technological interventions to improve functional ability of older adults: Evidence and gap map

This is the final version. Available on open access from Wiley via the DOI in this frecordThis is a protocol for a Campbell Evidence and Gap Map. The objectives are to identify and assess the available evidence on health, social care and technological interventions to improve functional ability among older adults

A kinematic analysis of a haptic handheld stylus in a virtual environment: a study in healthy subjects

<p>Abstract</p> <p>Background</p> <p>Virtual Reality provides new options for conducting motor assessment and training within computer-generated 3 dimensional environments. To date very little has been reported about normal performance in virtual environments. The objective of this study was to evaluate the test-retest reliability of a clinical procedure measuring trajectories with a haptic handheld stylus in a virtual environment and to establish normative data in healthy subjects using this haptic device.</p> <p>Methods</p> <p>Fifty-eight normal subjects; aged from 20 to 69, performed 3 dimensional hand movements in a virtual environment using a haptic device on three occasions within one week. Test-retest stability and standardized normative data were obtained for all subjects.</p> <p>Results</p> <p>No difference was found between test and retest. The limits of agreement revealed that changes in an individual's performance could not be detected. There was a training effect between the first test occasion and the third test occasion. Normative data are presented.</p> <p>Conclusion</p> <p>A new test was developed for recording the kinematics of the handheld haptic stylus in a virtual environment. The normative data will be used for purposes of comparison in future assessments, such as before and after training of persons with neurological deficits.</p

Development of postural adjustments during reaching in typically developing infants from 4 to 18 months

Knowledge on the development of postural adjustments during infancy, in particular on the development of postural muscle coordination, is limited. This study aimed at the evaluation of the development of postural control during reaching in a supported sitting condition. Eleven typically developing infants participated in the study and were assessed at the ages of 4, 6, 10 and 18 months. We elicited reaching movements by presenting small toys at an arm’s length distance, whilst activity of multiple arm, neck and trunk muscles was recorded using surface EMG. A model-based computer algorithm was used to detect the onset of phasic muscle activity. The results indicated that postural muscle activity during reaching whilst sitting supported is highly variable. Direction-specific postural activity was inconsistently present from early age onwards and increased between 10 and 18 months without reaching a 100 % consistency. The dominant pattern of activation at all ages was the ‘complete pattern’, in which all direction-specific muscles were recruited. At 4 months, a slight preference for top-down recruitment existed, which was gradually replaced by a preference for bottom-up recruitment. We conclude that postural control during the ecological task of reaching during supported sitting between 4 and 18 months of age is primarily characterized by variation. Already from 4 months onwards, infants are—within the variation—sometimes able to select muscle recruitment strategies that are optimal to the task at hand

Bayesian Integration and Non-Linear Feedback Control in a Full-Body Motor Task

A large number of experiments have asked to what degree human reaching movements can be understood as being close to optimal in a statistical sense. However, little is known about whether these principles are relevant for other classes of movements. Here we analyzed movement in a task that is similar to surfing or snowboarding. Human subjects stand on a force plate that measures their center of pressure. This center of pressure affects the acceleration of a cursor that is displayed in a noisy fashion (as a cloud of dots) on a projection screen while the subject is incentivized to keep the cursor close to a fixed position. We find that salient aspects of observed behavior are well-described by optimal control models where a Bayesian estimation model (Kalman filter) is combined with an optimal controller (either a Linear-Quadratic-Regulator or Bang-bang controller). We find evidence that subjects integrate information over time taking into account uncertainty. However, behavior in this continuous steering task appears to be a highly non-linear function of the visual feedback. While the nervous system appears to implement Bayes-like mechanisms for a full-body, dynamic task, it may additionally take into account the specific costs and constraints of the task

Observing Virtual Arms that You Imagine Are Yours Increases the Galvanic Skin Response to an Unexpected Threat

Multi-modal visuo-tactile stimulation of the type performed in the rubber hand illusion can induce the brain to temporarily incorporate external objects into the body image. In this study we show that audio-visual stimulation combined with mental imagery more rapidly elicits an elevated physiological response (skin conductance) after an unexpected threat to a virtual limb, compared to audio-visual stimulation alone. Two groups of subjects seated in front of a monitor watched a first-person perspective view of slow movements of two virtual arms intercepting virtual balls rolling towards the viewer. One group was instructed to simply observe the movements of the two virtual arms, while the other group was instructed to observe the virtual arms and imagine that the arms were their own. After 84 seconds the right virtual arm was unexpectedly “stabbed” by a knife and began “bleeding”. This aversive stimulus caused both groups to show a significant increase in skin conductance. In addition, the observation-with-imagery group showed a significantly higher skin conductance (p<0.05) than the observation-only group over a 2-second period shortly after the aversive stimulus onset. No corresponding change was found in subjects' heart rates. Our results suggest that simple visual input combined with mental imagery may induce the brain to measurably temporarily incorporate external objects into its body image