Many people with cerebral palsy experience disturbances in posture and balance, which contribute to overall motor dysfunction. The cerebral palsied tend to have abnormal sitting and standing posture, and demonstrate poor balance compared to healthy individuals of the same stage of development. For example, some children with cerebral palsy have trouble adjusting their posture and sitting independently; both postural aberrations and poor balance contribute to difficulties with ambulation. Most postural and balance problems arise from muscle abnormalities, but some forms of physical therapy appear to help with postural control and balance in the cerebral palsy patient.
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Postural problems play a central role in the motor dysfunction of children with cerebral palsy (CP). Therefore, they spend more time in sitting than in standing to perform vital tasks of daily life. The focus of this article is to describe the pathophysiology of postural control in sitting and outline some implications for management and treatment. In general, children with CP exhibit muscular activity counteracting forces that disturb equilibrium. Only 'non-sitting' children with severe CP lack such 'direction-specific' adjustments, possibly ruling out achievement of independent sitting. Most frequently, the children display dysfunctions in the adaptation of the adjustment. Typical characteristics of this adaptation in children with CP are a top-down recruitment of postural muscles, an excessive degree of antagonistic coactivation, and an incomplete adaptation of the EMG-amplitude to task specific constraints. Despite our knowledge on the pathophysiology underlying the postural problems in children with CP, little 'high-level' evidence (according to Sackett) exists on how different interventions can affect these problems. Therapeutic attention to promote motor performance in sitting focuses on adaptive seating, tilting of the support surface, and ample, variable training in motivating settings. The challenge facing us now is to provide evidence about the efficacy of specific treatment approaches facilitating that children reach an optimal level of functioning in daily life.
[Carlberg, E. B. & Hadders-Algra, M. (2005). Postural dysfunction in children with cerebral palsy: Some implications for therapeutic guidance. Neural Plasticity, 12(2-3), 221-8.]
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The present paper gives an overview of the knowledge currently available on muscular dyscoordination underlying postural problems in children with cerebral palsy (CP). Such information is a prerequisite for developing successful therapeutic interventions in children with CP. Until now, three children with CP functioning at GMFCS (Gross Motor Function Classification System) level V have been documented. The children totally or partially lacked direction specificity in their postural adjustments and could not sit independently for more than 3 seconds. Some children functioning at GMFCS level IV have intact direction-specific adjustments, whereas others have problems in generating consistently direction-specific adjustments. Children at GMFCS levels I to III have an intact basic level of control but have difficulties in fine-tuning the degree of postural muscle contraction to the task-specific conditions, a dysfunction more prominently present in children with bilateral spastic CP than in children with spastic hemiplegia. The problems in the adaptation of the degree of muscle contraction might be the reason that children with CP, more often than typically developing children, show an excess of antagonistic coactivation during difficult balancing tasks and a preference for cranial-caudal recruitment during reaching. This might imply that both stereotypies might be regarded as functional strategies to compensate for the dysfunctional capacity to modulate subtly postural activity.
[van der Heide, J. C. & Hadders-Algra, M. (2005). Postural muscle dyscoordination in children with cerebral palsy. Neural Plasticity, 12(2-3), 197-203.]
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Children with cerebral palsy (CP) display postural problems, largely interfering with daily life activities. Clarification of neural mechanisms controlling posture in these children could serve as a base for more successful intervention. Studies on postural adjustments following horizontal forward and backward displacements of a movable platform in ten school-age children with spastic diplegia and non-disabled controls revealed that sitting CP children, like standing CP children, show direction specific postural adjustments, indicating that the basic pattern of muscle coordination in these conditions is conserved. Dysfunctions are especially present in the modulation of the response pattern of ventral muscles during forward translations. They consist of: (1) a stereotyped and non-variable activation of all ventral muscles; (2) an abnormal top-down muscle recruitment; and (3) an excessive degree of antagonistic co-activation. The altered patterns of muscle coordination could be the result of two interacting mechanisms, the primary deficit due to the early brain damage and a compensation due to the postural instability. Especially the latter dysfunction furnishes opportunities for therapeutic help.
[Brogen, E., Hadders-Algra, M. & Forssberg, H. (1998). Postural control in sitting children with cerebral palsy. Neuroscience and Biobehavioral Reviews, 22(4), 591-6.]
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In this review we explore studies related to constraints on balance and walking in children with cerebral palsy (CP) and the efficacy of training reactive balance (recovering from a slip induced by a platform displacement) in children with both spastic hemiplegic and diplegic CP. Children with CP show (a) crouched posture, contributing to decreased ability to recover balance (longer time/increased sway); (b) delayed responses in ankle muscles; (c) inappropriate muscle response sequencing; (d) increased coactivation of agonists/antagonists. Constraints on gait include (a) crouched gait; (b) increased co-activation of agonists/antagonists; (c) decreased muscle activation; (d) spasticity. The efficiency of balance recovery can be improved in children with CP, indicated by both a reduction in the total center of pressure path used during balance recovery and in the time to restabilize balance after training. Changes in muscle response characteristics contributing to improved recovery include reductions in time of contraction onset, improved muscle response organization, and reduced co-contraction of agonists/antagonists. Clinical implications include the suggestion that improvement in the ability to recover balance is possible in school age children with CP.
[Woollacott, M. H. & Shumway-Cook, A. (2005). Postural dysfunction during standing and walking in children with cerebral palsy: What are the underlying problems and what new therapies might improve balance? Neural Plasticity, 12(2-3), 211-9.]
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BACKGROUND: Children with cerebral palsy often suffer from a lack of balance compared with typically developing children. Because balance capacity is relevant to functional activities, reliable and valid functional balance measures are crucial for the pediatric clinical setting. OBJECTIVE: This study examined the reliability and validity of 3 functional balance measures. METHODS: Thirty children aged 60 to 142 months with Gross Motor Function Classification System (GMFCS) levels of I to IV were recruited. For test-retest reliability, the same physical therapist administered the Functional Reach Test (FRT), Berg Balance Scale (BBS), and Timed Up and Go (TUG) twice. For interrater reliability, the testing processes were video recorded and later scored by another therapist. For convergent validity, children with cerebral palsy received the Gross Motor Function MEASURES: (GMFM), walking speed, and 10-second sit-to-stand test within 1 week and the results evaluated. RESULTS: The 3 functional balance measures had excellent test-retest reliability (intraclass correlation coefficient [ICC] >0.95) and interrater reliability (ICC = 0.98-1.00). With regard to convergent validity, the BBS and the TUG were highly correlated with GMFM total score, walking speed, and the 10-second sit-to-stand test. The discriminate validity indicates that the FRT can distinguish children with cerebral palsy with different GMFCS levels, whereas the BBS total score and TUG failed to distinguish between children with cerebral palsy with GMFCS levels of I and II. CONCLUSION: The 3 functional balance measures are simple, valid, and reliable for examining children with cerebral palsy and are thus suitable for clinical practice.
[Gan, S. M., Tung, L. C., Tang, Y. H. & Wang, C. H. (2008). Psychometric properties of functional balance assessment in children with cerebral palsy. Neurorehabilitation and Neural Repair, 22(6), 745-53.]
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OBJECTIVES: This study investigated differences in reactive balance abilities of typically developing children and those with spastic diplegia. Recovery from balance threats was compared by: (i) Platform velocity and amplitude thresholds: Speed and size of platform movement at which children required assistance to remain upright, (ii) percentage of trials with feet-in-place vs. loss of balance, and (iii) center of pressure measures. Participants included 8 children with spastic diplegic cerebral palsy, 15 developmentally matched children (similar walking stages) and 21 age-matched control children. METHODS: Backward platform movements graded as easy, moderate and difficult were unexpectedly imposed on children standing on a moveable platform. RESULTS: Children with cerebral palsy (CP) had lower platform velocity thresholds, greater percentages of loss of balance trials, increased distances and increased frequency of directional changes in center-of-pressure (COP) trajectories than control children. Older children with CP fell more often than those under 5 years. Greatest differences between children with and without CP were found in comparisons based on age rather than developmental levels. CONCLUSIONS: Using balance perturbations that challenged children with CP to the limits of their balance abilities effectively identified age performance differences and differences compared to typically developing children. Implications for rehabilitation programs are presented.
[Burtner, P. A., Woollacott, M. H., Craft, G. L. & Roncesvalles, M. N. (2007). The capacity to adapt to changing balance threats: A comparison of children with cerebral palsy and typically developing children. Developmental Neurorehabilitation, 10(3), 249-60.]
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Postural control deficits have been suggested to be a major component of gait disorders in cerebral palsy (CP). Standing balance was investigated in 23 ambulatory children and adolescents with spastic diplegic CP, ages 5 to 18 years, and compared with values of 92 children without disability, ages 5 to 18 years, while they stood on a force plate with eyes open or eyes closed. The measurements included center of pressure calculations of path length per second, average radial displacement, mean frequency of sway, and Brownian random motion measures of the short-term diffusion coefficient, and the long-term scaling exponent. In the majority of children with CP (14 of 23) all standing balance values were normal. However, approximately one-third of the children with CP (eight of 23) had abnormal values in at least two of the six center of pressure measures. Thus, mean values for path length, average radial displacement, and diffusion coefficient were higher for participants with CP compared with control individuals with eyes open and closed (p<0.05). Mean values for frequency of sway and the long-term scaling exponent were lower for participants with CP compared with control participants (p<0.05). Increased average radial displacement was the most common (nine of 23) postural control deficit. There was no increase in abnormal values with eyes closed compared with eyes open for participants with CP, indicating that most participants with CP had normal dependence on visual feedback to maintain balance. Identification of those children with impaired standing balance can delineate factors that contribute to the patient's gait disorder and help to guide treatment.
[Rose, J., Wolff, D. R., Jones, V. K., Bloch, D. A., Oehlert, J. W. & Gamble, J. G. (2002). Postural balance in children with cerebral palsy. Developmental Medicine and Child Neurology, 44(1), 58-63.]
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Following recent advances in the analysis of centre-of-pressure (COP) recordings, we examined the structure of COP trajectories in ten children (nine in the analyses) with cerebral palsy (CP) and nine typically developing (TD) children while standing quietly with eyes open (EO) and eyes closed (EC) and with concurrent visual COP feedback (FB). In particular, we quantified COP trajectories in terms of both the amount and regularity of sway. We hypothesised that: (1) compared to TD children, CP children exhibit a greater amount of sway and more regular sway and (2) concurrent visual feedback (creating an external functional context for postural control, inducing a more external focus of attention) decreases both the amount of sway and sway regularity in TD and CP children alike, while closing the eyes has opposite effects. The data were largely in agreement with both hypotheses. Compared to TD children, the amount of sway tended to be larger in CP children, while sway was more regular. Furthermore, the presence of concurrent visual feedback resulted in less regular sway compared to the EO and EC conditions. This effect was less pronounced in the CP group where posturograms were most regular in the EO condition rather than in the EC condition, as in the control group. Nonetheless, we concluded that CP children might benefit from therapies involving postural tasks with an external functional context for postural control.
[Donker, S. F., Ledebt, A., Roerdink, M., Savelsbergh, G. J. & Beek, P. J. (2008). Children with cerebral palsy exhibit greater and more regular postural sway than typically developing children. Experimental Brain Research, 184(3), 363-70.]
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Studies on the development of automatic postural responses in both typically developing children and children with cerebral palsy were performed. With the appearance of "pull-to-stand" behavior, typically developing children first began to show muscle responses to platform movements in mainly the ankle muscles. With increased development, additional agonist muscles were added to the response pattern and a consistent distal to proximal sequence began to emerge. Well-organized responses were seen with the onset of independent stance and walking, along with the reduction of antagonist muscle co-activation. The older children with cerebral palsy who were pre-walkers had immature muscle activation patterns like those seen in the typically developing children at the pull-to-stand stage of development. These included disorganized muscle responses and increased frequency of coactivation of both proximal-distal and agonist-antagonist muscles. In order to determine if musculoskeletal constraints contributed to these response patterns, normal children were asked to stand in a crouched posture similar to that of children with CP. This caused postural muscle response patterns to more closely approximate those of children with spastic diplegia.
[Woollacott, M. H. & Burtner, P. (1996). Neural and musculoskeletal contributions to the development of stance balance control in typical children and in children with cerebral palsy. Acta Paediatrica. Supplement [Norway], 416, 58-62.]
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PURPOSE: We reviewed research on the effect of adaptive seating on sitting posture/postural control in children with cerebral palsy. Second, we examined whether changes in postural control related to changes in other aspects of functioning. METHODS: Electronic database/hand searches were undertaken to locate studies published in English. Reviewers screened studies for inclusion criteria, extracted data, indexed outcomes to the International Classification of Functioning, Disability and Health, assigned levels of evidence, and assessed study quality. RESULTS: Thirteen of 14 articles used group designs and the other a single-subject design. Conflicting findings were reported for saddle seats and optimal seat/back angle for improving sitting posture/postural control. Significant improvements were reported with seat inserts, external supports, and modular seating systems. Evidence supporting effects of postural control on functional abilities was limited. CONCLUSIONS: Future studies on the effects of adaptive seating should describe participants with standardized classification systems and employ stronger research designs.
[Chung, J., Evans, J., Lee, C., Rabbani, Y., Roxborough, L. & Harris, S. R. (2008). Effectiveness of adaptive seating on sitting posture and postural control in children with cerebral palsy. Pediatric Physical Therapy, 20(4), 303-17.]
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A repeated-measures experimental cross-over study was conducted with school-aged children with spastic cerebral palsy (spastic CP) to compare the effects of flat-bench versus saddle-bench seating on postural control and reaching motions. The saddle bench allowed significantly better postural control as measured by the clinical rating scale Sitting Assessment for Children with Neuromotor Dysfunction and by a study-defined variable, Spinal Extension. No statistically significant differences were found for any other variables using aggregate data-analysis techniques. However, the group results and those of single-subject data analysis suggest that the saddle seat may help such children to develop and maintain seated postural control and upper-extremity movement patterns.
[Reid, D. T. (1996). The effects of the saddle seat on seated postural control and upper-extremity movement in children with cerebral palsy. Developmental Medicine and Child Neurology, 38(9), 805-15.]