Impaired force coordination during object release in children with hemiplegic cerebral palsy

Recent studies on hand motor control in children with cerebral palsy (CP) have focused on the coordination of fingertip forces during the grasping and lifting of objects. However, little is known about the ability to replace and release an object from grasp, a function that is just as important for fine dexterity. The present study examines the coordination of fingertip forces during the replacement and release of an object (either 200 g or 400 g) from grasp in 14 children (aged between 7 and 13 years) with hemiplegic CP and in 14 age-matched typically developing children. The results indicate that children with hemiplegic CP abruptly replaced the object but had a prolonged and uncoordinated release of the grasp. Unlike what was seen in the control children, the grip and load forces decreased sequentially in the children with CP. However, all the children could appropriately scale the rate of force decrease based on somatosensory weight-related information from the ongoing lift. The results provide further information about the impaired hand skills in children with hemiplegic CP.     

Grip force coordination during bimanual tasks in unilateral cerebral palsy

Aim The aim of the study was to investigate coordination of fingertip forces during an asymmetrical bimanual task in children with unilateral cerebral palsy (CP). Method Twelve participants (six males, six females; mean age 14y 4mo, SD 3.3y; range 9–20y;) with unilateral CP (eight right‐sided, four left‐sided) and 15 age‐matched typically developing participants (five males, 10 females; mean age 14y 3mo, SD 2.9y; range 9–18y,) were included. Participants were instructed to hold custom‐made grip devices in each hand and place one device on top of the other. The grip force and load force were recorded simultaneously in both hands. Results Temporal coordination between the two hands was impaired in the participants with CP (compared with that in typically developing participants), that is they initiated the task by decreasing grip force in the releasing hand before increasing the force in the holding hand. The grip force increase in the holding hand was also smaller in participants with CP (involved hand/non‐dominant hand releasing, p<0.001; non‐involved hand/dominant hand releasing, p=0.007), indicating deficient scaling of force amplitude. The impairment was greater when participants with CP used their non‐involved hand as the holding hand. Interpretation Temporal coordination and scaling of fingertip forces were impaired in both hands in participants with CP. The non‐involved hand was strongly affected by activity in the involved hand, which may explain why children with unilateral CP prefer to use only one hand during tasks that are typically performed with both hands.     

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.     

Fingertip forces during object manipulation in children with hemiplegic cerebral palsy. II: bilateral coordination

The present study examines the coordination of fingertip forces during object manipulation in both the involved and non-involved hand of 14 children with hemiplegic cerebral palsy (CP) aged between 8 and 14 years. While no impairment could be observed in the non-involved hand, subtle deficits in the sequencing of the grip-lift movement were observed in all children tested in this hand. However, they were able to scale the fingertip force output of the non-involved hand in advance (use anticipatory control) based on the object's weight. In the second experiment in this paper, we tested whether the anticipatory control can be generalized across hands. The results indicate that sensory information from the non-involved hand can be used for anticipatory scaling of isometric force increase during subsequent lifts with the contralateral involved hand. These findings suggest that the initial lack of anticipatory control usually observed in the involved hand of children with hemiplegic CP is likely to be based on disturbed sensory input.     

Fingertip forces during object manipulation in children with hemiplegic cerebral palsy. I: anticipatory scaling

Previous studies of grasping and object manipulation in children with cerebral palsy (CP) have suggested a dichotomy in the ability to use anticipatory control (planning) of the fingertip force output, depending on the type of sensory information (tactile or proprioceptive) on which it is based. The present study further explores this issue by testing the ability of 15 children with hemiplegic CP aged between 8 and 14 years to scale the fingertip force output in advance during the lifting of small objects whose weight and surface texture are varied. The results indicate that children with hemiplegia can use anticipatory control based on both the weight and texture of the object, but require a greater number of trials than age-matched children without CP (control children) before they can do so. We suggest that the initial lack of anticipatory control results from an indistinct internal representation of the object's physical properties due to disturbed sensory mechanisms, which may have direct implications for therapeutic intervention.     

Development of hand-arm bimanual intensive training (HABIT) for improving bimanual coordination in children with hemiplegic cerebral palsy

Constraint-induced (CI) movement therapy is a physical intervention that has been receiving increasing attention in pediatric rehabilitation. So far, the evidence suggests that practice associated with CI therapy may improve impaired unimanual hand function in some children with hemiplegic cerebral palsy (CP). However, CI therapy has several important limitations. Most importantly, children with hemiplegia have impairments in bimanual coordination beyond their unilateral impairments. Thus, an intervention approach to increase functional independence during activities of daily living by using both hands in cooperation is needed. Here we briefly review the etiology of hemiplegic CP, describe studies of pediatric CI therapy efficacy in relation to the etiology, discuss the conceptual and practical limitations of CI therapy for this population, and describe bimanual coordination impairments in children with hemiplegia. Finally, we introduce a new intervention for children with hemiplegia, hand-arm bimanual intensive training (HABIT), to address the limitations of CI therapy and to improve bimanual coordination. HABIT retains the two major elements of pediatric CI therapy (intensive structured practice and child-friendliness). The proposed methodology demonstrates that extensive targeted practice can be provided in a child-friendly manner without using a physical restraint, although the efficacy of such an approach remains to be determined.     

Relation between clinical measures and fine manipulative control in children with hemiplegic cerebral palsy

The present investigation examines the relation between various clinical measures and the performance of a functional precision grip-lift task. Fifteen children with hemiplegic cerebral palsy (CP), aged 8 to 14 years, and 15 age-matched control children grasped and lifted an object whose surface texture was varied while their fingertip forces were recorded. The force coordination was compared with tactile sensibility, grip strength, manual dexterity, and spasticity using correlational and regression analyses. The findings highlight the importance of tactile sensibility in this task. However, the manner in which sensibility was related varied for the sensory adaptation of fingertip forces, the anticipatory scaling of the force increase, and the smooth transitions between the temporal phases comprising the grip-lift task. The findings also indicate that spasticity affects some measures of the task, but not others, suggesting that the relation between spasticity and motor performance may not be absolute. The results further suggest that the impairments in grasping in children with hemiplegic CP are largely but not exclusively due to disturbed sensory mechanisms which may have direct implications for therapeutic intervention.     

Manual skill,hand skill asymmetry,and neuropsychological test performance in schoolchildren with spastic cerebral palsy

Bilateral hand skill assessment with a computerised version of the Peg Moving Task, and neuropsychological testing, were performed in 30 children aged 7 to 8 years with spastic cerebral palsy (CP) and without mental retardation, diplegia (n = 10), right hemiplegia (n = 10), or left hemiplegia (n = 10), and in 30 controls. Compared to controls: (i) 30% of the hemiplegic children showed impairment of the unaffected hand and 70% of the diplegic children showed impairment in both hands; (ii) children with CP were impaired only in oral repetition and in visual‐motor tasks. Results of neuropsychological testing were not significantly different between the three groups of children with CP. Right minus left asymmetry in hand skill was not related to neuropsychological testing; however, degree of impairment of the right hand was associated with phonological and metaphonological skills, and of the left hand with visuospatial and counting performance. Hand skill was related to the ability to perform many daily living manual activities. It is concluded that impairment of hand function, rather than the side of the more affected hand, is related to neuropsychological deficits in children with cerebral palsy.     

Children with spastic hemiplegia are equally able as controls in maintaining a precise percentage of maximum force without visually monitoring their performance

In this study the hypothesis was tested that children with spastic hemiplegia rely more on externally guided visual feedback when trying to keep force constant with their affected hand (AH) as compared to their non-affected hand (NAH) and as compared to controls. An isometric force task in which a cursor had to be moved to a visually specified target that disappeared half way the task, was performed by 19 children with cerebral palsy (CP), spastic hemiplegia, aged between 5 and 16 years and an aged matched control group. It was found that the absolute deterioration of performance after withdrawal of target visualization did differ between AH, NAH and controls. The absolute error was smaller and the variability was larger in the hemiplegic hand. However, the normalized force error and co-efficient of variation increased similarly between groups. Furthermore, power spectrum density analysis of the force signal showed that both hands in both groups had a similar loss in the energy in the 2-3 Hz range when target visualization was removed. These results suggest that CP children are equally able to produce stable force without visually monitoring their performance than children without CP, provided they are allowed to operate within their own force range.     

Influence of dual task constraints on gait performance and bimanual coordination during walking in children with unilateral Cerebral Palsy

The purpose of the current study was to evaluate the effects of dual task constraints on walking and bimanual coordination for children with and without unilateral Cerebral Palsy (CP). Ten children with unilateral CP (age 7–11 years; MACS levels I–II) and ten age-matched typically developed children were asked to first stand still while holding a box level (standing condition), second, to walk along a path (baseline condition), and third to walk again while carrying a box steady and level (dual task condition) at a preferred speed. The results showed that children with unilateral CP decreased their walking speed, stride length, step width, and toe clearance from the floor under dual task constraints when compared to the baseline condition (all p's < 0.05), however, typically developing children did not change. Children with unilateral CP also had less level box carrying, larger vertical box movement, and larger elbow movements when compared to typically developing children under dual task condition (all p's < 0.05). Dual task constraints with a secondary motor task like the current walking with a box task seemed challenging for children with unilateral CP. Therefore, future treatments or assessments should consider using dual task constraints to manipulate the difficulty of tasks.     

Task-dependent selection of grasp kinematics and stiffness in human object manipulation

Object manipulation with the hand is a complex task. The task has redundancies at many levels, allowing many possibilities for the selection of grasp points, the orientation and posture of the hand, the forces to be applied at each fingertip and the impedance properties of the hand. Despite this inherent complexity, humans perform object manipulation nearly effortlessly. This article presents experimental findings of how humans grasp and manipulate objects, and examines the compatibility of grasps selected for specific tasks. This is accomplished by looking at the velocity transmission and force transmission ellipsoids, which represent the transmission ratios of the corresponding quantity from the joints to the object, as well as the stiffness ellipsoid which represents the directional stiffness of the grasp. These ellipsoids allow visualization of the grasp Jacobian and grasp stiffness matrices. The results show that the orientation of the ellipsoids can be related to salient task requirements.     

Bimanual force coordination in children with spastic unilateral cerebral palsy

In this study bimanual grip-force coordination was quantified using a novel “Gripper” system that records grip forces produced while holding a lower and upper unit, in combination with the lift force necessary to separate these units. Children with unilateral cerebral palsy (CP) (aged 5-14 years, n = 12) were compared to age matched typically developing (TD) children (n = 23). Compared to TD, the CP-group is much slower and takes 50% more time to generate grip and lift forces with more fixating force before lifting the upper unit. In addition the coordination between forces in both hands is reduced. The CP-group increases the lift force in the upper hand 2.5 times more than the holding force when pulling the two units apart, while this is only 1.5 times in TD. Moreover, the correlation between forces generated in both hands in the CP-group is lower. The lack of fine tuning of the forces, measured by the linearity error is increased, especially when the magnet load keeping the unit together is low. The results indicate an impaired pull-hold synergy between upper and lower hand and the lift force. Bimanual tasks evaluating bimanual grip and lift forces in children with CP and can give us new insights in the underlying force control mechanisms of the spastic hand.     

Task-Dependent Deficits during Object Release in Parkinson''s Disease

The present study examined fingertip forces during the replacement and release of an instrumented object on a table in eight subjects with Parkinson's disease (PD) both off and on medication and eight age-matched control subjects. Subjects performed the task at (1) their preferred speeds and (2) as fast as possible. During performance of the task at preferred speed, the duration of object replacement, the rate, and duration of force decrease following table contact for PD subjects were similar to that observed in the control subjects and were unaffected by medication. In contrast, the rates were significantly lower and durations longer in the PD subjects when the task was performed as fast as possible irrespective of medication. A similar result was obtained when subjects were asked to release their pinch force from predefined force levels while the object was fixed to the table surface. These results emphasize the importance of considering task requirements in order to delineate the specific task parameters associated with the movement impairments in Parkinson's disease.     

The effect of intensive bimanual training on coordination of the hands in children with congenital hemiplegia

Recent studies have suggested efficacy of intensive bimanual training in improving the quality and quantity of affected hand use in children with hemiplegia. However, it is not known whether such training affects the coordination of the two hands. In the present study, 20 children with congenital hemiplegia (age 4-10 years; MACS levels I-II) were randomly assigned to either an intensive bimanual training (Hand-Arm Bimanual Intensive Therapy: HABIT) group, or a control group consisting of equally intensive unimanual treatment (Constraint-Induced Movement Therapy, CIMT) for 6 h per day for 15 days (90 h). To assess their bimanual coordination, children were asked to open a drawer with one hand and manipulate its contents with the other hand. 3-D movement kinematics were recorded and subsequently analyzed by a blind evaluator. The role of the two hands was varied. Following treatment, superior improvement in bimanual coordination was found for the bimanual training group as indicated by greater movement overlap (the percentage of time with both hands engaged in the task p = 0.047) and better goal synchronization (reduced time differences between the two hands completing the task goals, p = 0.005). The results suggest that bimanual training improves the spatial-temporal control of the two hands, and are in agreement with the principle of practice specificity.     

Quantitative assessment of mirror movements in children and adolescents with hemiplegic cerebral palsy

Mirror movements in individuals with hemiplegic cerebral palsy (CP) may result from a reorganization of the central sensorimotor system. Motor performances of both hands were measured to characterize mirror activity (or mirroring) and hand functions in 22 participants (6 to 18 years) with hemiplegic CP and in 17 control participants. During a unimanual repetitive squeezing task, contractions of the active hand and fingertip forces of the opposite hand were recorded simultaneously. In the control group, slight mirror activity (or mirroring) was found that decreased with age. In participants with CP, mirror activity was 15 times stronger than in the control group, and was found at all age levels. Mirroring was more prominent in the unaffected hand of the CP group. The amount of mirror activity was not related to the degree of hemiplegia, which was assessed with measures of spasticity, strength, and dexterity. Mirror movements disturbed functional bimanual skills, although to some extent they could be suppressed by voluntary effort.     

Manual skill, hand skill asymmetry, and neuropsychological test performance in schoolchildren with spastic cerebral palsy

Bilateral hand skill assessment with a computerised version of the Peg Moving Task, and neuropsychological testing, were performed in 30 children aged 7 to 8 years with spastic cerebral palsy (CP) and without mental retardation, diplegia (n = 10), right hemiplegia (n = 10), or left hemiplegia (n = 10), and in 30 controls. Compared to controls: (i) 30% of the hemiplegic children showed impairment of the unaffected hand and 70% of the diplegic children showed impairment in both hands; (ii) children with CP were impaired only in oral repetition and in visual-motor tasks. Results of neuropsychological testing were not significantly different between the three groups of children with CP. Right minus left asymmetry in hand skill was not related to neuropsychological testing; however, degree of impairment of the right hand was associated with phonological and metaphonological skills, and of the left hand with visuospatial and counting performance. Hand skill was related to the ability to perform many daily living manual activities. It is concluded that impairment of hand function, rather than the side of the more affected hand, is related to neuropsychological deficits in children with cerebral palsy.     

Planning and coordination of a reach-grasp-eat task in children with hemiplegia

Children with hemiplegia have deficits in motor planning in addition to their impairments in movement of their more-affected upper extremity (UE). However, little is known about the relationship between motor planning and multi-segment coordination during functional activities in this population. In the present study, motor planning strategies and multi-segment coordination of the head, trunk, and UE were examined during a functional reach-grasp-eat task in children with hemiplegia. Ten children with hemiplegia (age 4-10 years; MACS levels I-II) and ten age-matched, typically developing children participated in the study. Children were asked to reach, grasp and transport a cookie to the mouth with one hand while 3-D kinematic analyses were performed. A more extended wrist (p = 0.001) and higher end-point position of grasping (p = 0.001) were found for both UEs of children with hemiplegia. The less-affected UE had greater trunk contribution (p = 0.018) and greater shoulder flexion (p = 0.002) and elbow extension (p = 0.005) during reaching compared to the TDC. The more-affected UE had impaired movement control with greater head rotation (p = 0.011), higher variability of end-point location in space (p = 0.001), greater trunk contribution (p = 0.018), and reduced wrist rotation (p = 0.007) compared with the less-affected UE and TDC. Additionally, delayed timing of maximum shoulder (p = 0.03) and elbow flexion (p = 0.008) during reaching, and maximum wrist pronation (p = 0.004) during eating were found for the more-affected UE. The results showed different multi-segment control for both UEs in children with hemiplegia compared to TDC. They also reflect impaired motor planning since the same movement strategies were used for both UEs. Furthermore, we suggest that inefficient multi-segment coordination of the more-affected UE is used to compensate for impaired motor planning and control.     

Relationship between neuromuscular body functions and upper extremity activity in children with cerebral palsy

Aim Our aim was to investigate the relationship between the dimensions of neuromuscular body function and elbow, forearm, and hand activity in the upper extremities in children/adolescents with spastic cerebral palsy (CP), within the framework of the World Health Organization International Classification of Functioning, Disability and Health. Method Twenty‐three participants (10 males, 13 females, mean age 13y, SD 3y, range 8–18y) with spastic CP (21 with hemiplegia, two with diplegia) at Manual Ability Classification System levels I to III participated in the study. Neuromuscular body function measures were (1) muscle strength in the elbow, forearm, and grip, (2) muscle tone in elbow flexors and forearm supinators, (3) active supination range and elbow extension range, and (4) force control at submaximal level in elbow flexion. Activity measures were actual use of the affected hand in bimanual activities (Assisting Hand Assessment) and instructed use of the affected hand (Melbourne Assessment of Unilateral Upper Limb Function). Results Nearly all the neuromuscular body function variables were significantly correlated with activity. The combination of active supination range and strength explained 74% of the variance in actual use, and the combination of active supination range and force control explained 74% of the variance in instructed use. Interpretation In high‐functioning children and adolescents with CP, limited active supination range and difficulties in generating and modulating force are strongly related to limitations in hand activity. Further studies are needed to establish cause and effect in this relationship.     

Prevalence of cerebral palsy in Turkish children between the ages of 2 and 16 years

The aim of this cross-sectional study was to determine the prevalence of cerebral palsy (CP) among children in Turkey between the ages of 2 and 16 years. Samples were selected from cities, towns, districts, and villages using the cluster sampling method; 41,861 children were selected. Data was collected by parental interview and physical examination. One hundred and eighty-six children were identified with CP. The prevalence of CP was determined as 4.4 per 1,000 live births and included postnatally acquired CP. Origin of CP was classified as prenatal in 49 (26.6%), perinatal/neonatal in 34 (18.5%), postnatal in 11 (5.9%), and unclassifiable in 90 participants (48.9%; data was unobtainable for two individuals). Type of CP was diplegia in 39.8% of children, hemiplegia in 28%, tetraplegia in 19.9%, ataxia in 5.9%, and dyskinetic in 6.4%. Prenatal factors were seen more frequently in the groups with a high socioeconomic status while perinatal factors were encountered more often in those with a low socioeconomic status (p<0.05). Place of residence and sex had no significant effect on the prevalence of CP (p>0.05). This cross-sectional study shows that the prevalence of CP in Turkey is higher than that in developed countries but the aetiology is probably similar. Although the high prevalence of CP in Turkey could originate from an increased level of obstetric and neonatal problems, the lack of a possible aetiological factor in approximately half the children suggests that the high level might also be due to other factors, such as genetic disorders.     

Relation between objectively measured feeding competence and nutrition in children with cerebral palsy

This study aimed to investigate the prevalence of undernutrition in children with cerebral palsy (CP) and to determine the relation with feeding ability. Ninety children with CP from special needs schools were examined. Undernutrition was diagnosed on one or more of the following criteria: weight <2nd centile, triceps or subscapular skinfold measurement <3rd centile, mid-arm circumference <5th centile. Feeding competence was scored with respect to seven specific oromotor tasks using the Multidisciplinary Feeding Profile. Thirty-six participants (40%) had diplegia, 29 (33%) quadriplegia, 13 (14%) hemiplegia, and 12 participants (13%) had dyskinetic CP. Age ranged from 2.6 to 18.7 years (mean 10.8 years). Forty-six percent (41 of 90) were undernourished. In all aspects of feeding, those undernourished had lower feeding competence scores compared to adequately nourished children (p<0.002). Each modality of feeding competence correlated significantly to the centiles of weight, triceps or subscapular skinfold measurement and mid-arm circumference (p<0.02). A positive association of weight, triceps skinfold measurement, and mid-arm circumference with chewing ability was present independent of other feeding modalities (p<0.05). Undernutrition was common in this group and was associated with poorer feeding ability.