Transfer of motor learning from virtual to natural environments in individuals with cerebral palsy

With the growing accessibility of computer-assisted technology, rehabilitation programs for individuals with cerebral palsy (CP) increasingly use virtual reality environments to enhance motor practice. Thus, it is important to examine whether performance improvements in the virtual environment generalize to the natural environment. To examine this issue, we had 64 individuals, 32 of which were individuals with CP and 32 typically developing individuals, practice two coincidence-timing tasks. In the more tangible button-press task, the individuals were required to ‘intercept’ a falling virtual object at the moment it reached the interception point by pressing a key. In the more abstract, less tangible task, they were instructed to ‘intercept’ the virtual object by making a hand movement in a virtual environment. The results showed that individuals with CP timed less accurate than typically developing individuals, especially for the more abstract task in the virtual environment. The individuals with CP did—as did their typically developing peers—improve coincidence timing with practice on both tasks. Importantly, however, these improvements were specific to the practice environment; there was no transfer of learning. It is concluded that the implementation of virtual environments for motor rehabilitation in individuals with CP should not be taken for granted but needs to be considered carefully.     

Bimanual coordination during a goal-directed task in children with hemiplegic cerebral palsy

Most studies of impaired hand function in children with hemiplegic cerebral palsy (CP) have focused on either the involved or the non-involved extremity in isolation. Coordination of the involved and non-involved hand during bimanual tasks in these children is not well understood. The present study examined bimanual coordination using a drawer-opening task under speed and hand constraints in 10 children with hemiplegic CP (5 males and 5 females, mean age 13y 5mo, range 8y to 16y) and 10 age-matched right-handed developing typically children (6 males and 4 females, mean age 13y 1mo). Children were asked to reach forward and open a drawer with one hand and then activate a light switch inside the drawer with the contralateral hand. The role of the two hands (open drawer and activate switch) and speed (self-paced vs fast-as-possible) were varied. The children with hemiplegic CP were slower (p<0.001) and less coordinated in this task, with reduced movement overlap of the two hands (p<0.001) and sequential completion of the two movement objectives (p<0.001). Moreover, the hand used for each task subcomponent affected task performance for the children with hemiplegic CP (p<0.05). Interestingly, faster speed facilitated better bimanual coordination for the children with hemiplegic CP (p<0.001). Results highlight the importance of movement constraints on task performance and suggest that movement speed might facilitate better bimanual coordination.     

Feasibility of event-related potential methodology to evaluate changes in cortical processing after rehabilitation in children with cerebral palsy: A pilot study

This study examined the feasibility of using event-related potentials (ERPs) to measure changes in cortical processing following an established rehabilitative intervention (constraint-induced movement therapy, CIMT) for children with cerebral palsy (CP). Sixteen participants with a diagnosis of hemiparetic CP, with a median age of 6 years, were assessed pre and immediately post CIMT and at 6-month follow-up, using a picture–word match/mismatch discrimination task and standard neurobehavioral measures. Intervention effects were evident in improved performance on behavioral tests of sensory and motor function and the increased mean ERP amplitude of the N400 match/mismatch response on the side ipsilateral to the lesion. These effects were maintained 6 months after the intervention. No such changes were observed on the side contralateral to the lesion. This research suggests that ERPs can measure rehabilitation-induced changes in neural function in children with CP.     

Evaluation and characterization of manual reaching in children with cerebral palsy: A systematic review

Manual reaching is used daily to perform manipulative tasks and activities of daily routine. Children with cerebral palsy (CP) have limitations in this activity, with functional loss as a possible consequence. This review aimed to gather studies that evaluated and characterized manual reaching in children with CP, with the purpose of identifying the aspects analyzed, as well as review and discuss the results in the studies and its relationship to the children's level of functionality. 17 studies were selected for this systematic review from the search in electronic databases. The studies showed that children with CP show deficits in several spatio-temporal variables of reaching compared to typical children, such as longer time to perform the activity, higher peak velocity, lower index of curvature, and greater number of units of motion, which indicates lower smoothness and linearity of the movements of upper limbs. The performance is influenced by the level of motor impairment and various manipulations of the task. However, more studies are needed that help translating these results into treatment strategies that facilitate the performance of manual activities in children with CP.     

Visual-perceptual impairment in a random sample of children with cerebral palsy

Several studies have tried to establish the prevalence of visual-perceptual impairment in children with physical disabilities, particularly in those with cerebral palsy (CP), but failed to take into account the selective impairment of non-verbal intelligence that is frequent in these children. This has resulted in the confounding of visual-perceptual and non-verbal intelligence impairment. In the present study we aimed to determine how widespread visual-perceptual impairment is in children with CP by evaluating perceptual ability together with the performance level on non-verbal intelligence subtests. All children (n=96; 44 females, 52 males) who attended an institute for children with physical disabilities were included (age ranged from 4 years 11 months to 21 years 5 months) who had a non-verbal mental age between 3 and 7 years; Total IQ was <85 in 91% of participants. They were given a grating acuity task and the visual-perceptual battery L94, comprising six visual object recognition and two visuoconstruction tasks. Relative to their performance level on non-verbal intelligence subtests, 37.5% of the children were impaired on at least one task, and 18.7% on two or more tasks. No child was impaired on the visuoconstruction tasks. Visual-perceptual impairment was highest among six children with brain malformation (67%), followed by spastic CP (40%), and brain damage acquired after the first year of life (38%). There was no difference in visual-perceptual impairment between the subtypes of spastic CP. Results are not secondary to visual acuity deficits, as only one L94 task was significantly correlated with acuity impairment. We conclude that visual-perceptual impairment is frequent in children with physical disabilities, and not restricted to children with CP of hypoxic-ischaemic origin.     

Motion analysis of the upper extremity in children with unilateral cerebral palsy—An assessment of six daily tasks

Restrictions in range of motion of the upper extremity are common in patients with unilateral cerebral palsy (CP). The purpose of this study was to investigate movement deviations of the upper extremity in children with unilateral CP by means of 3D motion capture as well as by the use of easy to use scores and questionnaires (MACS, MRC, MAS, ABILHAND-Kids). 16 children with a spastic, unilateral CP were included and compared to a group of 17 typically developing adolescents (TD). The movement time and range of motion (ROM) of six uni- and bimanual daily tasks were compared and correlated with the scores and questionnaires. Movement times increased significantly with involvement according to MACS in all tasks. The restrictions in ROM were pronounced in the forearm. As a compensatory mechanism the children of the MACS 2 and 3 groups showed increased trunk movement. Furthermore, there was a positive correlation between the MACS and the ABILHAND-Kids Questionnaire. In contrast to previous studies, which reported a correlation between the restrictions in ROM and the MACS, this study showed no consistent correlation between the restrictions in ROM neither with the MACS nor with the ABILHAND-Kids. While the MACS and the ABILHAND-Kids function as a simple rating tool for clinical use, the detailed analysis of different daily tasks using 3-D-motion capture provides more detailed information about the movement deviations and spatiotemporal parameters.     

Sit-to-stand movement in children with cerebral palsy: a critical review

Sit-to-stand (STS) movement is widely performed in daily life and an important pre requisite for acquisition of functional abilities. However, STS is a biomechanical demanding task which requires high levels of neuromuscular coordination, muscle strength and postural control. As children with cerebral palsy (CP) exhibit a series of impairments in body structures and functions, STS movement performance could be impaired in this population. Thus, this article aimed to review studies that had described how STS movement is performed by children with CP, the factors that influence it and the methodological procedures adopted in it analyses. A search was performed by one reviewer in relevant databases. In all, 12 articles were identified and 9 were selected for the present review. It was detected a large variation in sample characteristics and methodological issues among studies. In fact, standardization of the method applied to STS movement analysis is not fully established. With regard to STS performance, children with CP exhibited variations among them and also when compared with their typical peers. Moreover extrinsic factors appear to influence STS movement performance in these children and its manipulation could be incorporated into rehabilitation protocols. Moreover, the relationship between STS movement and functionality in reviewed articles was not reported. Therefore the review allowed to observe that STS movement has been under-explored in children with CP, with a lack of standardized methodologies and a not well established relationship between this movement and functionality. Thus, further studies about STS movement in CP are necessary.     

The development of anticipatory action planning in children with unilateral cerebral palsy

Background Previous studies suggest that compromised bimanual performance experienced by children with unilateral cerebral palsy (CP) is not only due to difficulties in action execution but may also be a result of impaired anticipatory action planning.Aims The effect of age and side of hemiplegia were examined and the relationship between anticipatory action planning, unimanual capacity and bimanual performance was explored.Methods and procedures Using a multi-centre, prospective, cross-sectional observational design, anticipatory action planning was analyzed in 104 children with unilateral cerebral palsy, aged 6–12 years, using the sword task.Outcomes and results Anticipatory action planning did not improve with age in children with unilateral CP, aged between 6–12 years. No differences were found between children with left or right hemiplegia. Finally, anticipatory action planning was not related to unimanual capacity or bimanual performance.Conclusion and implications This study demonstrates anticipatory action planning, measured using the sword task, does not improve with age in children with unilateral CP and is not related to bimanual performance or laterality. Future studies of anticipatory action planning in children with unilateral CP should consider using measures that require effective anticipatory action planning for successful task completion rather than end state comfort.     

Assessment of motor imagery in cerebral palsy via mental chronometry: The case of walking

Recent studies show varying results on whether motor imagery capacity is compromised in individuals with cerebral palsy (CP). Motor imagery studies in children predominantly used the implicit hand laterality task. In this task participants judge the laterality of displayed hand stimuli. A more explicit way of studying motor imagery is mental chronometry. This paradigm is based on the comparison between the movement durations of actually performing a task and imagining the same task. The current study explored motor imagery capacity in CP by means of mental chronometry of a whole body task. Movement durations of 20 individuals with CP (mean age = 13 years, SD = 3.6) were recorded in two conditions: actual walking and imagined walking. Six unique trajectories were used that varied in difficulty via manipulation of walking distance and path width. We found no main effect of condition (actual walking versus imagining) on movement durations. Difficulty of the walking trajectory did affect movement durations. In general, this was expressed by an increase in movement durations with increasing difficulty of the task. No interaction between task difficulty and movement condition was found. Our results show that task difficulty has similar effects on movement durations for both actual walking and imagined walking. These results exemplify that the tested individuals were able to use motor imagery in an explicit task involving walking. Previous studies using the implicit hand laterality task showed varying results on motor imagery capacity in CP. We therefore conclude that motor imagery capacity is task dependent and that an explicit paradigm as the one used in this study may reveal the true motor imagery capacity. The implications of these findings for the use of motor imagery training are discussed.     

Motor learning of a bimanual task in children with unilateral cerebral palsy

Children with unilateral cerebral palsy (CP) have been shown to improve their motor performance with sufficient practice. However, little is known about how they learn goal-oriented tasks. In the current study, 21 children with unilateral CP (age 4–10 years old) and 21 age-matched typically developed children (TDC) practiced a simple bimanual speed stack task over 15 days of practice. Both groups demonstrated their ability to learn the current bimanual task, but their rate of improvement and learning pattern differed. Children with unilateral CP overall were slower and improved ~10% less than TDC. Most of the improvement occurred during the first 3 days for the TDC, whereas performance did not plateau until 6–8 days for the children with unilateral CP. This initial slower learning rate for children with unilateral CP was also confirmed by better fitting of the curve to an exponential function than the power law function (p < 0.05). Therefore, when working with children with unilateral CP, sufficient practice is important (two to three times more than for TDC), and delayed improvement is expected.     

Activity limitation in hemiplegic cerebral palsy: evidence for disorders in motor planning

Review of the definition of cerebral palsy (CP) has focused on disorders of movement and posture development that cause activity limitations. Recent research provides new insights into CP, showing that activity limitation in individuals with hemiplegic CP is not exclusively caused by disorders related to movement execution, but is also related to the planning of movements. In this review article, converging evidence is presented suggesting that, in addition to movement execution impairments, impairments in movement planning may also limit the performance of activities of daily living. Evidence from studies of fingertip-force planning and anticipatory planning in object manipulation tasks is discussed.     

The link between impaired theory of mind and executive function in children with cerebral palsy

The aim of the study was to explore the relationship between theory of mind (ToM) deficits and executive function (EF) impairments in children with cerebral palsy (CP), 42 CP with children and 42 typically developing (TD) children, acting as controls, were assessed on the tasks of ToM (false belief and faux pas) and EF (inhibition, updating and shifting). Results showed that CP children had deficits both in ToM and EF tasks. The correlation analyses showed that two EF components (inhibition and updating) were strongly related to false belief and faux pas in both two groups. We also found correlation between shifting and false belief and faux pas. However, this correlation was only found in TD children and not in children with CP. These findings suggest that children with CP lag behind TD children in both ToM and EF. Further, the results reveal, interestingly, that ToM deficits in CP children might be related to their inhibition and updating impairments, but not to shifting impairments.     

Quantification of object manipulation in children with cerebral palsy

A shape-posting task was studied in 30 control, eight hemiplegic and 10 diplegic children, to determine how differences in object manipulation between such children could be quantified. Conical, cylindrical and triangular-shaped objects were posted through a hole in a perspex screen, three times each with both preferred and non-preferred hands. Four variables were defined to describe kinematic aspects of the task: adjustment inefficiency, mean transport velocity, adjustment distance to be completed in the placing phase and adjustment velocity in the placing phase. As expected, total task time was increased in subjects with cerebral palsy and with more complex shapes, and reduced by repetition. The four kinematic variables reduced the variation in task time between individual children by 79%, between sets of like objects by 62%, and the residual variation by 63%. Adjustment inefficiency was increased and mean transport velocity reduced in subjects with cerebral palsy, whereas repetition had the opposite effect. It is suggested that combined alterations in adjustment inefficiency and transport velocity reflect changes in the intrinsic uncertainty of a movement and that this quantity is decreased by repetition and increased in cerebral palsy.     

Interlimb coupling in children with hemiplegic cerebral palsy during reaching and grasping at speed

This investigation examined reaching and grasping at speed in children with hemiplegic cerebral palsy. Of particular interest was the effect of the movement of the less affected limb on the more affected one. Using 3D kinematic analysis and standard video recordings, 11 children with hemiplegia of varying degrees of severity were examined performing three reaching tasks at speed. The data were analysed and the extent and nature of the interlimb coupling occurring in each child were assessed using a number of different variables. The results are discussed in terms of spatial, temporal, and postural coupling. All children coupled to some degree but differed in the degree and type of coupling. Speed facilitated coupling which was stronger during the first part of the movement in all three tasks. The variables affecting coupling included the type of coupling, the nature of the task, the importance of context, and the stage in the movement.     

Speech-associated labiomandibular movement in Mandarin-speaking children with quadriplegic cerebral palsy: a kinematic study

The purpose of this study was to investigate the speech-associated labiomandibular movement during articulation production in Mandarin-speaking children with spastic quadriplegic (SQ) cerebral palsy (CP). Twelve children with SQ CP (aged 7-11 years) and 12 age-matched healthy children as controls were enrolled for the study. All children underwent analysis of percentage of consonants correct (PCC) and kinematic analysis of speech tasks using the Vicon Motion 370 system. Kinematic parameters included utterance duration, displacement and velocity of the lip and jaw, coefficient of variation (CV) of lip utterance duration, and spatial and temporal coupling of labiomandibular movement of speech produced in mono-syllable (MS) and poly-syllable (PS) tasks. Children with CP showed lower temporal coupling (MS, p = 0.015; PS, p = 0.007), but not spatial coupling, of labiomandibular movement than healthy children. Children with CP had greater CVs (MS, p = 0.003; PS, p = 0.010) and the peak opening displacement and velocity of lower lip and jaw (p < 0.05) and lower PCC (p < 0.001) than healthy children. Children with SQ CP displayed labiomandibular coupling movement impairment, especially in the aspect of temporal coupling. These children also had high temporal oromotor variability and needed to make more effort to coordinate the labiomandibular movement for speech production.     

The influence of errors during practice on motor learning in young individuals with cerebral palsy

The aim of this study was to investigate the effect of errors during practice on motor skill learning in young individuals with cerebral palsy (CP). Minimizing errors has been validated in typically developing children and children with intellectual disabilities as a method for implicit learning, because it reduces working memory involvement during learning. The present study assessed whether a practice protocol that aims at minimizing errors can induce implicit learning in young individuals with CP as well. Accordingly, we hypothesized that reducing errors during practice would lead to enhanced learning and a decrease in the dependency of performance on working memory. Young individuals with CP practiced an aiming task following either an error-minimizing (N = 20) or an error-strewn (N = 18) practice protocol. Aiming accuracy was assessed in pre-, post- and retention test. Dual task performance was assessed to establish dependency on working memory. The two practice protocols did not invoke different amounts or types of learning in the participants with CP. Yet, participants improved aiming accuracy and showed stable motor performance after learning, irrespective of the protocol they followed. Across groups the number of errors made during practice was related to the amount of learning, and the degree of conscious monitoring of the movement. Only participants with relatively good working memory capacity and a poor initial performance showed a rudimentary form of (most likely, explicit) learning. These new findings on the effect of the amount of practice errors on motor learning in children of CP are important for designing interventions for children and adolescents with CP.     

Effect of seat surface inclination on postural stability and forward reaching efficiency in children with spastic cerebral palsy

The purpose of this study was to examine the effect of seat surface inclination on postural stability and forward reaching efficiency in 10 children with spastic cerebral palsy (CP) and 16 typically developing (TD) children. The children performed a static sitting and a forward reaching task while sitting on a height- and inclination-adjustable stool at flat, three anterior-inclined, and three posterior-inclined positions. Postural stability was expressed as normalized (with body weight) peak vertical ground reaction force, center of pressure displacement in the anterior/posterior directions (COP_AP), in the medial/lateral directions (COP_ML), and sway ratio (COP_AP/COP_ML). Reaching efficiency was expressed as reaction time and movement time of arm reaching forward to a target. The results showed that seat inclination affected children's postural stability and the effects were comparable for CP and TD children in all measures except for COP_ML. Children with CP presented much larger COP_ML than TD children at the posterior-inclined positions relative to the flat and the anterior-inclined positions. Seat inclination affected reaching efficiency for both groups of children equally. Efficiency was better at the anterior positions than the posterior positions. Anterior-inclined positions improved postural stability and reaching efficiency. Posterior positions posed greater postural challenge and the challenge was tougher for children with CP.     

Motor and Sensory Impairments in Children with Intractable Epilepsy

During a 3-year period (1988–1991), 72 children with severe intractable epilepsy were studied. A standardized protocol for assessment of motor and sensory function was designed for school age children. Function was quantified on a 4-point scale on 47 items, including gross motor function, balance, coordination, strength, range of motion (ROM), velocity, fine motor function, sensation, perception, and neurologic tests. Classification of handicaps according to World Health Organization (WHO) definitions was performed. Videotape documentation completed the assessment. Evaluation of treatment services showed that provision of rehabilitation services had been insufficient and provided only for children with additional major movement disorders, mainly cerebral palsy (CP) cases. To minimize the handicap in children with severe epilepsy, it is essential to clarify the total sensorimotor impairment pattern, including balance, co-ordination, and perceptual capacity. Impairments in these functions are, as shown in this study, frequent and exist independent of major disabilities such as mental retardation or cerebral palsy. When several neuroimpairments were identified, a multiplicative rather than an additive effect on the total handicap was evident.     

Impaired visually guided weight-shifting ability in children with cerebral palsy

The ability to control voluntary weight shifting is crucial in many functional tasks. To our knowledge, weight shifting ability in response to a visual stimulus has never been evaluated in children with cerebral palsy (CP). The aim of the study was (1) to propose a new method to assess visually guided medio-lateral (M/L) weight shifting ability and (2) to compare weight-shifting ability in children with CP and typically developing (TD) children. Ten children with spastic diplegic CP (Gross Motor Function Classification System level I and II; age 7–12 years) and 10 TD age-matched children were tested. Participants played with the skiing game on the Wii Fit game console. Center of pressure (COP) displacements, trunk and lower-limb movements were recorded during the last virtual slalom. Maximal isometric lower limb strength and postural control during quiet standing were also assessed. Lower-limb muscle strength was reduced in children with CP compared to TD children and postural control during quiet standing was impaired in children with CP. As expected, the skiing game mainly resulted in M/L COP displacements. Children with CP showed lower M/L COP range and velocity as compared to TD children but larger trunk movements. Trunk and lower extremity movements were less in phase in children with CP compared to TD children. Commercially available active video games can be used to assess visually guided weight shifting ability. Children with spastic diplegic CP showed impaired visually guided weight shifting which can be explained by non-optimal coordination of postural movement and reduced muscular strength.