Abstracts
Background:
Postural control deficits can impair functional performance in children with cerebral palsy (CP) in daily living activities.
Objective:
To verify the relationship between standing static postural control and the functional ability level in children with CP.
Method:
The postural control of 10 children with CP (gross motor function levels I and II) was evaluated during static standing on a force platform for 30 seconds. The analyzed variables were the anteroposterior (AP) and mediolateral (ML) displacement of the center of pressure (CoP) and the area and velocity of the CoP oscillation. The functional abilities were evaluated using the mean Pediatric Evaluation of Disability Inventory (PEDI) scores, which evaluated self-care, mobility and social function in the domains of functional abilities and caregiver assistance.
Results:
Spearman's correlation test found a relationship between postural control and functional abilities. The results showed a strong negative correlation between the variables of ML displacement of CoP, the area and velocity of the CoP oscillation and the PEDI scores in the self-care and caregiver assistance domains. Additionally, a moderate negative correlation was found between the area of the CoP oscillation and the mobility scores in the caregiver assistance domain. We used a significance level of 5% (p <0.05).
Conclusions:
We observed that children with cerebral palsy with high CoP oscillation values had lower caregiver assistance scores for activities of daily living (ADL) and consequently higher levels of caregiver dependence. These results demonstrate the repercussions of impairments to the body structure and function in terms of the activity levels of children with CP such that postural control impairments in these children lead to higher requirements for caregiver assistance.
cerebral palsy; postural balance; children; functionality; PEDI; rehabilitation
Contextualização:
Os déficits de controle postural em crianças com PC podem comprometer suas atividades na rotina diária.
Objetivo:
Verificar a relação entre o controle postural em ortostatismo de crianças com PC e suas habilidades funcionais.
Método:
O controle postural de dez crianças PC (GMFCS I e II) foi avaliado em ortostatismo na plataforma de força por 30 segundos. Variáveis analisadas: deslocamento ântero-posterior e médio-lateral do centro de pressão (CoP), área e velocidade de oscilação do CoP. As habilidades funcionais foram avaliadas por meio do Pediatric Evaluation of Disability Inventory (PEDI), considerando-se escores de autocuidado, mobilidade e função social nos domínios habilidades funcionais e assistência do cuidador.
Resultados:
O teste de correlação de Spearman verificou a relação entre controle postural e funcionalidade. Constatou-se correlação negativa forte entre as variáveis amplitude ML de deslocamento do CoP, área de oscilação do CoP e entre a variável de velocidade média de oscilação do CoP e os escores do domínio de autocuidado. Observou-se também correlação negativa moderada entre área de oscilação do CoP e mobilidade. O nível de significância adotado foi de 5% (p<0,05).
Conclusões:
Crianças com maiores oscilações do CoP em ortostatismo apresentam maiores escores de assistência do cuidador para a realização de AVDs, indicando maiores níveis de dependência. Isso demonstra as repercussões dos componentes de estrutura e função do corpo sobre o nível de atividade em crianças com PC, uma vez que o comprometimento do controle postural pode levar a uma maior dependência das crianças em relação a seus cuidadores.
paralisia cerebral; equilíbrio; crianças; funcionalidade; PEDI; reabilitação
Introduction
Children with cerebral palsy exhibit motor disorders that are characterized by
uncoordinated movements, maladaptive muscle length changes and postural control
dysfunction11. Brianeze ACGS, Cunha AB, Peviane SM, Miranda VCR, Tognetti VBL,
Rocha NACF, et al. Efeito de um programa de fisioterapia funcional em crianças
com paralisia cerebral associado a orientações ao cuidadores: estudo preliminar.
Fisioter Pesqui. 2009;16:40-5.
,
22. Mancini MC, Fiúza PM, Rebelo JM, Magalhães LC, Coelho ZAC, Paixão
ML, et al. Comparação do desempenho de atividades funcionais em crianças com
desenvolvimento normal e crianças com paralisia cerebral. Arq Neuro-Psiquiatr.
2002;60:446-52. http://dx.doi.org/10.1590/S0004-282X2002000300020
http://dx.doi.org/10.1590/S0004-282X2002...
. Postural control ensures the proper positioning of the body in space and
maintains stability and body alignment by maintaining the projection of the center
of pressure (CoP) within the limits of the support base33. Chen J, Woollacott MH. Lower extremity kinetics for balance
control in children with cerebral palsy. J Mot Behav. 2007;39:306-16.
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,
44. Graaf-Peters VB, Blauw-Hospers CH, Dirks T, Bakker H, Bos AF,
Hadders-Algra M. Development of postural control in typically developing
children and children with cerebral palsy: Possibilities for intervention?
Neurosc Biobehav Rev. 2007;31:1191-200. PMid:17568673.
http://dx.doi.org/10.1016/j.neubiorev.2007.04.008
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.
Children with CP experience difficulties with controlling the body's position in
space, performing anticipatory adjustments for executing functional activities and
reacting to unexpected perturbations of balance33. Chen J, Woollacott MH. Lower extremity kinetics for balance
control in children with cerebral palsy. J Mot Behav. 2007;39:306-16.
PMid:17664172. http://dx.doi.org/10.3200/JMBR.39.4.306-316
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,
55. Carlberg EB, Hadders-Algra M. Postural disfunction in children
with cerebral palsy: some implications for therapeutic guidance. Neural
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,
66. Liu WY, Zaino CA, McCoy SW. Anticipatory postural adjustments in
children with cerebral palsy and children with typical development. Ped Phys
Ther. 2007;19:188-95. PMid:17700347 .
http://dx.doi.org/10.1097/PEP.0b013e31812574a9
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. The primary causes of the deficits in fine posture control adjustment in
children with CP include the order of muscle recruitment, the rate of
agonist/antagonist co-activation, incoordination of joint segments and recruitment
of fewer motor units responsible for coordinating postural responses66. Liu WY, Zaino CA, McCoy SW. Anticipatory postural adjustments in
children with cerebral palsy and children with typical development. Ped Phys
Ther. 2007;19:188-95. PMid:17700347 .
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7. Donker SF, Ledebt A, Roerdink M, Savelsbergh GJP, Beek PJ.
Children with cerebral palsy exhibit greater and more regular postural sway than
typically developing children. Exp Brain Resp. 2008;84:363-70. PMid:17909773
PMCid:PMC2137946. http://dx.doi.org/10.1007/s00221-007-1105-y
http://dx.doi.org/10.1007/s00221-007-110...
-
88. Rose J, Wolff DR, Jones VK, Bloch DA, Gamble JG. Postural balance
in children with cerebral palsy. Dev Med Child Neurol. 2002;44:58-63.
PMid:11811652. http://dx.doi.org/10.1017/S0012162201001669
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. Together, these changes increase the difficulty of controlling the body in
space and define low levels of coordination between the joint segments of the
body99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409.. Therefore, the child with CP presents with increased CoP oscillation to
achieve adaptive success in their daily activities44. Graaf-Peters VB, Blauw-Hospers CH, Dirks T, Bakker H, Bos AF,
Hadders-Algra M. Development of postural control in typically developing
children and children with cerebral palsy: Possibilities for intervention?
Neurosc Biobehav Rev. 2007;31:1191-200. PMid:17568673.
http://dx.doi.org/10.1016/j.neubiorev.2007.04.008
http://dx.doi.org/10.1016/j.neubiorev.20...
. Because of the neuromotor deficits and biomechanical changes in these
children, the alignment between body segments and CoP maintenance within the limits
of the support base are compromised99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409.
,
1010. Roncesvalles MN, Woollacott MW, Burtner PA. Neural factors
underlying reduced postural adaptability in children with cerebral palsy.
Neuroreport. 2002;1:2407-10. http://dx.doi.org/10.1097/00001756-200212200-00006
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.
Therefore, the set of dysfunctions that are manifested in CP can affect postural
control while standing and thus compromise functional activities. This inference has
been reinforced by the findings reported in some studies, which have claimed that
these children might face difficulties with maintaining upright posture maintenance
and performing activities of daily living (ADLs)33. Chen J, Woollacott MH. Lower extremity kinetics for balance
control in children with cerebral palsy. J Mot Behav. 2007;39:306-16.
PMid:17664172. http://dx.doi.org/10.3200/JMBR.39.4.306-316
http://dx.doi.org/10.3200/JMBR.39.4.306-...
,
1111. Hsue BJ, Miller F, Su FC. The dynamic balance of the children
with cerebral palsy and typical developing during gait. Part I: Spatial
relationship between COM and COP trajectories. Gait Posture. 2009;29:465-70.
PMid:19111469. http://dx.doi.org/10.1016/j.gaitpost.2008.11.007
http://dx.doi.org/10.1016/j.gaitpost.200...
, thus reducing their level of independence33. Chen J, Woollacott MH. Lower extremity kinetics for balance
control in children with cerebral palsy. J Mot Behav. 2007;39:306-16.
PMid:17664172. http://dx.doi.org/10.3200/JMBR.39.4.306-316
http://dx.doi.org/10.3200/JMBR.39.4.306-...
,
66. Liu WY, Zaino CA, McCoy SW. Anticipatory postural adjustments in
children with cerebral palsy and children with typical development. Ped Phys
Ther. 2007;19:188-95. PMid:17700347 .
http://dx.doi.org/10.1097/PEP.0b013e31812574a9
http://dx.doi.org/10.1097/PEP.0b013e3181...
,
88. Rose J, Wolff DR, Jones VK, Bloch DA, Gamble JG. Postural balance
in children with cerebral palsy. Dev Med Child Neurol. 2002;44:58-63.
PMid:11811652. http://dx.doi.org/10.1017/S0012162201001669
http://dx.doi.org/10.1017/S0012162201001...
,
1212. Liao HF, Gan SM, Lin KH, Lin JJ. Effects of Weight resistence on
the temporal parameters and electromyography of sit to stand movements in
children with and without cerebral palsy. J Phys Med Rehabil. 2010;89:99-106.
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.
In addition, studies have reported functional consequences of these deficits in
postural control mechanisms on the gait1111. Hsue BJ, Miller F, Su FC. The dynamic balance of the children
with cerebral palsy and typical developing during gait. Part I: Spatial
relationship between COM and COP trajectories. Gait Posture. 2009;29:465-70.
PMid:19111469. http://dx.doi.org/10.1016/j.gaitpost.2008.11.007
http://dx.doi.org/10.1016/j.gaitpost.200...
,
1212. Liao HF, Gan SM, Lin KH, Lin JJ. Effects of Weight resistence on
the temporal parameters and electromyography of sit to stand movements in
children with and without cerebral palsy. J Phys Med Rehabil. 2010;89:99-106.
PMid:20090426. http://dx.doi.org/10.1097/PHM.0b013e3181c55874
http://dx.doi.org/10.1097/PHM.0b013e3181...
and reach of children with CP1414. Cherng RJ, Lin HC, Ju YH, Ho CS. Effect of seat surface
inclination on postural stability and forward reaching efficiency in children
with spastic cerebral palsy. Res Dev Disabil. 2009;30:1420-7. PMid:19647395.
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1515. Näslund A, Sundelin G, Hirschfeld H. Reach performance and
postural adjustments during standing in children with severe spastic diplegia
using dynamic ankle-foot orthoses. J Rehabil Med. 2007;39:715-23. PMid:17999010.
http://dx.doi.org/10.2340/16501977-0121
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and have revealed difficulties in situations that involve rapid changes in
load bearing1616. Stackhouse C, Shewokis PQ, Pierce SR, Smith B, McCarthy J,
Tucker C. Gait initiation in children with cerebral palsy. Gait Posture.
2007;26:301-8. PMid:17081756. http://dx.doi.org/10.1016/j.gaitpost.2006.09.076
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and unexpected disruptions in upright posture99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409.
,
1717. Woollacott MH, Shumway-Cook A. Postural dysfunction during
standing and walking in children with cerebral palsy: what are the underlying
problems and what new therapies might improve balance? Neural Plast.
2005;12:263-72. PMid:16097489 PMCid:PMC2565447.
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required to perform some activities of daily living.
Although the literature has highlighted an apparent relationship between postural
control and functionality33. Chen J, Woollacott MH. Lower extremity kinetics for balance
control in children with cerebral palsy. J Mot Behav. 2007;39:306-16.
PMid:17664172. http://dx.doi.org/10.3200/JMBR.39.4.306-316
http://dx.doi.org/10.3200/JMBR.39.4.306-...
,
1515. Näslund A, Sundelin G, Hirschfeld H. Reach performance and
postural adjustments during standing in children with severe spastic diplegia
using dynamic ankle-foot orthoses. J Rehabil Med. 2007;39:715-23. PMid:17999010.
http://dx.doi.org/10.2340/16501977-0121
http://dx.doi.org/10.2340/16501977-0121...
, in a database search, no studies were found that correlated static postural
control with the functional ability levels displayed by children with CP. Knowledge
of this relationship demonstrates the importance of maintaining stability and
alignment between the body segments in an upright posture while performing
functional activities. Additionally, this knowledge allows one to extrapolate force
platform data analyses to these children's activities of daily living.
The literature describes instruments for evaluating functional abilities such as the
Pediatric Evaluation of Disability Inventory (PEDI), which has
been reliably standardized and validated for the Brazilian population1818. Chen KL, Tseng MH, Hu FC, Koh CL. Pediatric Evaluation of
Disability Inventory: A cross-cultural comparison of daily function between
Taiwanese and American children. Res Dev Disabil. 2010;31:1590-1600.
PMid:20542661. http://dx.doi.org/10.1016/j.ridd.2010.05.002
http://dx.doi.org/10.1016/j.ridd.2010.05...
,
1919. Mancini MC. Inventário de Avaliação Pediátrica de Incapacidade
(PEDI): manual da versão brasileira adaptada. Belo Horizonte: Universidade
Federal de Minas Gerais; 2005.. This evaluation tool enables investigators to measure functionality based
on activities that children would normally perform during their daily routines and
to measure their dependence on a caregiver2020. Mancini MC, Alves ACM, Schaper C, Figueiredo EM, Sampaio RF,
Coelho ZA, et al. Gravidade da Paralisia Cerebral e Desempenho Funcional. Rev
Bras Fisioter. 2004;8:253-60..
Given the potential of PEDI to assess the functional abilities of children with CP by using activities similar to those performed in their daily routines and the lack of studies that have correlated static postural control and the functional ability level in this population, it was believed that studies examining this relationship could demonstrate the direct consequences of deficits in postural control on the level of independence of children with CP in terms of activities involving mobility, self-care and social function.
Therefore, the present study aimed to investigate the relationship between static postural control while standing and the functional ability levels of children with CP.
Method
Participants
The present study was essentially a cross-sectional study with an applied aspect.
Children of both genders who had been diagnosed with spastic CP at levels I and
II of gross motor function (GMFCS)2121. Palisano R, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B.
Development and reliability of a system to classify gross motor function in
children with cerebral palsy. Dev Med Child Neurol. 1997;39(4):214-23.
PMid:9183258. http://dx.doi.org/10.1111/j.1469-8749.1997.tb07414.x
http://dx.doi.org/10.1111/j.1469-8749.19...
and who were between 5 and 12 years of age were selected. It has been
reported that in this age range, sensory integration for postural control is
enhanced by improvements in sensory integrative mechanisms and increased vision
contributions2222. Shumway-Cook A, Woollacott MH. The growth of stability: Postural
control from a developmental perspective. J Mot Behav. 1985;17:131-47.
http://dx.doi.org/10.1080/00222895.1985.10735341
http://dx.doi.org/10.1080/00222895.1985....
, thus allowing the generation of responses that ensure successful
balance maintenance.
Children were required to be able to follow the simple commands needed to perform the proposed tasks and to maintain an upright posture without support for at least 30 seconds. Parents or guardians were required to sign informed consent (IC) forms for their children to participate in the study. Children who exhibited lower limb muscle shortening that would limit their function in an upright position, such as shortening of the hamstrings, adductors, hip flexor or plantar flexor muscles, were excluded. Children who had undergone orthopedic surgery of the lower limbs in the last 12 months or had received botulinum toxin injections in the last 6 months were also excluded.
Procedures
This study was submitted to the National Council of Health and the Ethics Committee on Human Research of the Universidade Federal de São Carlos (UFSCar), São Carlos, SP, Brazil and was approved (Opinion No. 490/2010). After the informed consent form was signed, the children underwent an initial assessment to collect anthropometric and orthopedic data.
Postural control for each child was then evaluated while in a standing position.
A Bertec 400 force platform (EMG Sistem do Brasil(r), São José dos
Campos, SP, Brazil) was used at an acquisition frequency of 100 Hz. The children
were asked to remain standing on the force platform with their feet parallel to
and aligned with the sides of their hips77. Donker SF, Ledebt A, Roerdink M, Savelsbergh GJP, Beek PJ.
Children with cerebral palsy exhibit greater and more regular postural sway than
typically developing children. Exp Brain Resp. 2008;84:363-70. PMid:17909773
PMCid:PMC2137946. http://dx.doi.org/10.1007/s00221-007-1105-y
http://dx.doi.org/10.1007/s00221-007-110...
. The initial foot position was marked to ensure consistency throughout
the trials. While standing on the platform, the children were asked to remain as
still as possible for 30 seconds while looking at a circular figure positioned 1
meter in front of them at eye level. Each child performed the task a total of 5
times (2 adaptation and 3 valid attempts). Each trial was separated by a rest
period of 120 seconds2323. Ferdjallah M, Harris GF, Smith P, Wertsch JJ. Analysis of
postural control synergies during quiet standing in healthy children and
children with cerebral palsy. Clin Biomech. 2002;17:203-10.
http://dx.doi.org/10.1016/S0268-0033(01)00121-8
http://dx.doi.org/10.1016/S0268-0033(01)...
.
An evaluation of each child's functional abilities was then performed using the
PEDI instrument, which had been standardized and validated for the Brazilian
population1919. Mancini MC. Inventário de Avaliação Pediátrica de Incapacidade
(PEDI): manual da versão brasileira adaptada. Belo Horizonte: Universidade
Federal de Minas Gerais; 2005.. This instrument evaluates children between the ages of 6 months and 7.5
years. However, given that the children evaluated in this study had functional
abilities compatible with the age limits determined by the PEDI, we evaluated
children older than the upper age limit indicated by the instrument.
Accordingly, it was not possible to use the normative score calculations and
therefore only the raw scores for each child were used22. Mancini MC, Fiúza PM, Rebelo JM, Magalhães LC, Coelho ZAC, Paixão
ML, et al. Comparação do desempenho de atividades funcionais em crianças com
desenvolvimento normal e crianças com paralisia cerebral. Arq Neuro-Psiquiatr.
2002;60:446-52. http://dx.doi.org/10.1590/S0004-282X2002000300020
http://dx.doi.org/10.1590/S0004-282X2002...
.
The PEDI is divided into 3 distinct parts that provide information about 3 different areas of functional performance. The first part evaluated the functional abilities of children in the areas of self-care, mobility and social function. Each of the 197 evaluated items received a score of 1 if the child performed the function or 0 if he/she could not perform it. The second part quantified the assistance provided by the caregiver to the child while performing self-care (8 items), mobility (7 items) and social function (5 items) tasks. In this second part, each item is evaluated on an ordinal scale from 0 to 5, where 0 indicated a need for maximum assistance and 5 indicated independence. The sum of the scores yielded a total raw score for each of the 3 areas of functional abilities. Therefore, a higher score corresponded to better functional performance for the child. The third part of the PEDI provided information about the modifications necessary to perform functional tasks in the previously described 3 areas (self care, mobility & social function).
For the present study, only data from the first 2 parts of the instrument, functional abilities and caregiver assistance, were used from among the 3 evaluated domains (self-care, mobility and social function)2020. Mancini MC, Alves ACM, Schaper C, Figueiredo EM, Sampaio RF, Coelho ZA, et al. Gravidade da Paralisia Cerebral e Desempenho Funcional. Rev Bras Fisioter. 2004;8:253-60.. For the scale application, the evaluator was trained and achieved an intraobserver agreement index of 85%.
Data analysis and statistics
Data were captured from the kinetic force platform analysis using Bertec software
(Bertec Corporation, Columbus, OH, USA), and data analysis and dependent
variable calculations were performed by implementing routines in the MATLAB
software environment (Mathworks Inc., Natick, MA, USA). Data were normalized
according to the children's weights77. Donker SF, Ledebt A, Roerdink M, Savelsbergh GJP, Beek PJ.
Children with cerebral palsy exhibit greater and more regular postural sway than
typically developing children. Exp Brain Resp. 2008;84:363-70. PMid:17909773
PMCid:PMC2137946. http://dx.doi.org/10.1007/s00221-007-1105-y
http://dx.doi.org/10.1007/s00221-007-110...
. The force platform data were filtered in MATLAB software, using a
fourth-order low-pass Butterworth digital filter with a cutoff frequency of 5
Hz.
The kinetic variables of static postural control analyzed in the present study
while standing were the anteroposterior amplitude of the CoP displacement (Amp
AP; in cm), the mediolateral amplitude of the CoP displacement (Amp MLin cm),
the CoP oscillation area (Area; c22. Mancini MC, Fiúza PM, Rebelo JM, Magalhães LC, Coelho ZAC, Paixão
ML, et al. Comparação do desempenho de atividades funcionais em crianças com
desenvolvimento normal e crianças com paralisia cerebral. Arq Neuro-Psiquiatr.
2002;60:446-52. http://dx.doi.org/10.1590/S0004-282X2002000300020
http://dx.doi.org/10.1590/S0004-282X2002...
) and d) the velocity of the CoP oscillation (Vel in cm/s)2424. Duarte M, Freitas SMSF. Revision of posturography based on force
plate for balance evaluation. Rev Bras Fisioter. 2010;14(3):183-92. PMID:
20730361. http://dx.doi.org/10.1590/S1413-35552010000300003
http://dx.doi.org/10.1590/S1413-35552010...
.
The dependent variables of the PEDI instrument were the raw instrument scores in the functional abilities area for the domains of self-care (FAsc), mobility (FAmob) and social function (FAsf) and in the caregiver assistance area for the domains of self-care (CAsc), mobility (CAmob) and social function (CAsf).
Descriptive results were generated by calculating the means and standard deviation. For the statistical data analysis, the mean of the 3 trials performed on the force platform for each of the variables was used. The Shapiro-Wilk test confirmed the absence of normality in the data distribution (p≥0.05).
Spearman's correlation was used to study the relationship between the mean of the 3 attempts while standing on the force platform and the PEDI instrument scores because the data were not parametric. The rating value (r) proposed by Munro2525. Munro BH. Statistics methods for health care research. 3rd ed. Philadelphia: JB Lippincott; 1997. was used as a base. A correlation was performed between the variables, and the coefficient of determination was also calculated. The significance level was set at 5% for all analyses. SPSS software, version 10.0 (SPSS Inc., Chicago, IL, USA) was used for the analysis and to generate graphs.
Results
The study included 10 children with spastic CP (M [media]=9; ±4.9), 5 males and 5 females, including 7 children with spastic hemiplegic CP and 3 with spastic diplegic CP. The results for all correlations are shown in Table 1.
Spearman correlation (r) values for the standing static permanence variables: antero-posterior amplitude of CoP displacement (Amp AP), medio-lateral amplitude of CoP displacement (Amp ML), area of CoP oscillation (Area), mean velocity of CoP oscillation (Vel) and PEDI scores (p<0.05).
The present study found significant and negative correlations between the child's CoP behavior while standing and the functional abilities. There were also strong negative correlations between the variables of the ML amplitude of CoP displacement (r=-0.82, p<0.05), CoP oscillation area (r=-0.78, p<0.05) and mean velocity of the CoP oscillation (r=-0.70, p<0.05) and the self-care domain scores in the area of caregiver assistance. Additionally, there was a moderate negative correlation between the CoP oscillation area and the mobility scores (r=-0.63, p<0.05) in the area of caregiver assistance. The correlation values and coefficients of determination are shown in Table 2.
Presentation of significant correlations (r), statistic significance (p), correlation classification according to Munro and determination coefficient (%).
Based on the correlation coefficients shown in Table 2, the results suggest that while standing, 67% of the variability in the Amp ML of the CoP was related to variations in the self-care scores in the area of caregiver assistance, indicating that medial-lateral directional displacement resulted in 67% lower scores in the domain of self-care.
Additionally, 61% of the variability in the CoP oscillation area was related to variations in the scores for self-care in the area of caregiver assistance, indicating that increased and more rapid CoP oscillations were related to 61% lower self-care scores in the area of caregiver assistance. Moreover, 49% of the variability in the velocity of the CoP oscillation appeared to be related to variations in the self-care scores in the area of caregiver assistance, indicating that increased and more rapid CoP oscillations are related to 49% lower self-care scores in the area of caregiver assistance. Finally, 40% of the variability in the CoP oscillation area was related to variations in the mobility score in the area of caregiver assistance, indicating that larger areas of displacement resulted in 40% lower mobility scores.
Discussion
The aim of the present study was to investigate the relationship between postural control while standing and the functional ability level in children with CP via an analysis of variables related to the CoP behaviors while standing and an evaluation of the child's functional performance according to the PEDI instrument.
The results suggested that in children with CP, higher Amp ML values for CoP displacement and the area and mean velocity of the CoP oscillation correlated with lower scores in the area of caregiver assistance in the self-care and mobility domains of the PEDI.
This relationship meets the provisions of the International Classification of
Functioning, Disability and Health (ICF), which define the health status of
individuals as multi-directional relationships between different domains of health.
Accordingly, changes in body structure and function (such as deficits in postural
control as observed in CP) are related to the level of activity and
participation2626. Dos Santos AN, Pavão SL, Campos AC, Rocha NACF. International
classification of functioning, disability and health in children with cerebral
palsy. Disabil Rehab. 2012;34(12):1053-8. PMid:22107334.
http://dx.doi.org/10.3109/09638288.2011.631678
http://dx.doi.org/10.3109/09638288.2011....
. Therefore, the CoP behavior while standing might correlate with a child's
reduced performance in functional abilities and lower level of independence from
caregivers. Similarly, the deficits that are experienced by these children in
performing functional activities may be related to larger CoP excursions while
standing by restricting their participation in the environments in which they are
placed and limiting their experiences in different postures.
Among the children evaluated in the present study, changes in the body structure and function, which were represented by higher ML CoP displacement values (indicative of less control over the postural adjustments required to maintain balance2727. Patla A, Frank J, Winter D. Assessment of balance control in the elderly: major issues. Physiotherapy. 1990;42(2):89-97.), correlated with a greater reliance on their caregivers to perform self-care activities, including feeding, bathing, changing clothes, personal hygiene and bathroom use.
Previous studies have reported higher CoP displacement values in the ML direction at different positions for children with CP relative to their typical peers11. Brianeze ACGS, Cunha AB, Peviane SM, Miranda VCR, Tognetti VBL, Rocha NACF, et al. Efeito de um programa de fisioterapia funcional em crianças com paralisia cerebral associado a orientações ao cuidadores: estudo preliminar. Fisioter Pesqui. 2009;16:40-5.. According to the present results, the larger ML displacement might correlate significantly with the level of functionality in these children (67%), thus reflecting a deficit in maintaining proper oscillation while performing functional tasks as measured with the PEDI instrument. The other 33% might be related to the changes in tone or muscle strength that were commonly observed in these children.
The relationship between greater ML displacement and lower self-care domain scores
can be explained by the strategies employed by this population to maintain balance.
Typical children preferentially use an ankle strategy to prevent imbalances and
potential falls44. Graaf-Peters VB, Blauw-Hospers CH, Dirks T, Bakker H, Bos AF,
Hadders-Algra M. Development of postural control in typically developing
children and children with cerebral palsy: Possibilities for intervention?
Neurosc Biobehav Rev. 2007;31:1191-200. PMid:17568673.
http://dx.doi.org/10.1016/j.neubiorev.2007.04.008
http://dx.doi.org/10.1016/j.neubiorev.20...
,
99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409.. However, because of their neuromotor disorders, children with CP have
deficiencies in recruiting the muscles around the ankle joint44. Graaf-Peters VB, Blauw-Hospers CH, Dirks T, Bakker H, Bos AF,
Hadders-Algra M. Development of postural control in typically developing
children and children with cerebral palsy: Possibilities for intervention?
Neurosc Biobehav Rev. 2007;31:1191-200. PMid:17568673.
http://dx.doi.org/10.1016/j.neubiorev.2007.04.008
http://dx.doi.org/10.1016/j.neubiorev.20...
,
99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409.
,
2323. Ferdjallah M, Harris GF, Smith P, Wertsch JJ. Analysis of
postural control synergies during quiet standing in healthy children and
children with cerebral palsy. Clin Biomech. 2002;17:203-10.
http://dx.doi.org/10.1016/S0268-0033(01)00121-8
http://dx.doi.org/10.1016/S0268-0033(01)...
. Therefore, children with CP preferably use muscles around the hip99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409., a strategy that is associated with larger ML displacements2323. Ferdjallah M, Harris GF, Smith P, Wertsch JJ. Analysis of
postural control synergies during quiet standing in healthy children and
children with cerebral palsy. Clin Biomech. 2002;17:203-10.
http://dx.doi.org/10.1016/S0268-0033(01)00121-8
http://dx.doi.org/10.1016/S0268-0033(01)...
.
Therefore, neuromotor deficits such as changes in the order of muscle recruitment and the loss of interarticular coordination in children with CP99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in select groups of children with cerebral palsy: deficits in sensory organization and muscular coordination. Exp Brain Res. 1983;49:393-409. appear to be associated with a greater dependence on caregivers for the performance of certain activities, including bathing, brushing teeth, changing clothes and hair care. These activities are commonly performed while standing, the position in which the body is most intensely subjected to destabilizing forces.
Although it is essential for maintaining postural control while standing2323. Ferdjallah M, Harris GF, Smith P, Wertsch JJ. Analysis of
postural control synergies during quiet standing in healthy children and
children with cerebral palsy. Clin Biomech. 2002;17:203-10.
http://dx.doi.org/10.1016/S0268-0033(01)00121-8
http://dx.doi.org/10.1016/S0268-0033(01)...
, the Amp AP of the CoP displacement did not significantly correlate with the
children's level of functionality in any of the evaluated PEDI domains. It is
possible that displacements in this direction did not exhibit significant
variability in the children evaluated and thus it was not possible to find a
correlation. These children exhibited greater oscillations in the ML direction.
These results can be explained by the preference of children with CP for using the
hip strategy, which is reflected by the larger ML displacements, to maintain
balance2323. Ferdjallah M, Harris GF, Smith P, Wertsch JJ. Analysis of
postural control synergies during quiet standing in healthy children and
children with cerebral palsy. Clin Biomech. 2002;17:203-10.
http://dx.doi.org/10.1016/S0268-0033(01)00121-8
http://dx.doi.org/10.1016/S0268-0033(01)...
. Because these children are less able to activate the muscles around their
ankles, they recruit the hip muscles instead to maintain stability99. Nasher LM, Shumway-Cook A, Marin O. Stance posture control in
select groups of children with cerebral palsy: deficits in sensory organization
and muscular coordination. Exp Brain Res. 1983;49:393-409..
Additionally, children with higher CoP oscillation areas had lower scores in the
domains of self-care and mobility. Larger CoP oscillation areas indicate reduced
control over the body in response to body imbalance1717. Woollacott MH, Shumway-Cook A. Postural dysfunction during
standing and walking in children with cerebral palsy: what are the underlying
problems and what new therapies might improve balance? Neural Plast.
2005;12:263-72. PMid:16097489 PMCid:PMC2565447.
http://dx.doi.org/10.1155/NP.2005.211
http://dx.doi.org/10.1155/NP.2005.211...
,
2828. Sobera M, Siedlecka B, Syczewska M. Posture Control development
in children aged 2-7 years old, based on the changes of repetability of the
stability indices. Neurosci Lett. 2011;491:13-7. PMid:21215293.
http://dx.doi.org/10.1016/j.neulet.2010.12.061
http://dx.doi.org/10.1016/j.neulet.2010....
. The performance of self-care and mobility activities involves reaching for
and manipulating objects as well as deliberately moving the CoP44. Graaf-Peters VB, Blauw-Hospers CH, Dirks T, Bakker H, Bos AF,
Hadders-Algra M. Development of postural control in typically developing
children and children with cerebral palsy: Possibilities for intervention?
Neurosc Biobehav Rev. 2007;31:1191-200. PMid:17568673.
http://dx.doi.org/10.1016/j.neubiorev.2007.04.008
http://dx.doi.org/10.1016/j.neubiorev.20...
,
77. Donker SF, Ledebt A, Roerdink M, Savelsbergh GJP, Beek PJ.
Children with cerebral palsy exhibit greater and more regular postural sway than
typically developing children. Exp Brain Resp. 2008;84:363-70. PMid:17909773
PMCid:PMC2137946. http://dx.doi.org/10.1007/s00221-007-1105-y
http://dx.doi.org/10.1007/s00221-007-110...
,
1515. Näslund A, Sundelin G, Hirschfeld H. Reach performance and
postural adjustments during standing in children with severe spastic diplegia
using dynamic ankle-foot orthoses. J Rehabil Med. 2007;39:715-23. PMid:17999010.
http://dx.doi.org/10.2340/16501977-0121
http://dx.doi.org/10.2340/16501977-0121...
, which generates internal forces that produce instability and alter the
alignment between the body segments. Therefore, in the present study, postural
control was associated with independence in self-care in 61% of the children and
independence in mobility in 40% of the children. As noted, other factors that were
not evaluated in this study might also be related to the independence of children
with CP in terms of self-care and mobility activity performance.
Children with CP have larger CoP oscillation areas while standing2828. Sobera M, Siedlecka B, Syczewska M. Posture Control development
in children aged 2-7 years old, based on the changes of repetability of the
stability indices. Neurosci Lett. 2011;491:13-7. PMid:21215293.
http://dx.doi.org/10.1016/j.neulet.2010.12.061
http://dx.doi.org/10.1016/j.neulet.2010....
. These larger oscillation areas represent a better exploitation of the
support base to generate successful postural adjustments and avoid imbalance.
Because of their neuromotor deficits, children with CP experience more difficulty in
coordinating their responses to imbalance and thus must more broadly exploit their
support bases. This increased exploitation is intended to attract a greater number
of proprioceptive afferents with which to adjust the body positioning in space1515. Näslund A, Sundelin G, Hirschfeld H. Reach performance and
postural adjustments during standing in children with severe spastic diplegia
using dynamic ankle-foot orthoses. J Rehabil Med. 2007;39:715-23. PMid:17999010.
http://dx.doi.org/10.2340/16501977-0121
http://dx.doi.org/10.2340/16501977-0121...
,
2727. Patla A, Frank J, Winter D. Assessment of balance control in the
elderly: major issues. Physiotherapy. 1990;42(2):89-97.
,
2929. Heide JC, Hadders-Algra M. Postural muscle dyscoordination in
children with cerebral palsy. Neural Plast. 2005;12:197-203. PMid:16097487
PMCid:PMC2565449. http://dx.doi.org/10.1155/NP.2005.197
http://dx.doi.org/10.1155/NP.2005.197...
.
In the present study, the deficits in postural control regulation observed in
children with CP, which were represented by a greater oscillation area, were related
to lower levels of functionality, which were represented by a greater reliance of
the child on a caregiver for mobility task performance. Studies have indicated that
in children with CP, postural control, which is influenced by the child's neuromotor
disability severity55. Carlberg EB, Hadders-Algra M. Postural disfunction in children
with cerebral palsy: some implications for therapeutic guidance. Neural
Plasticity. 2005;12:221-28. PMid:16097490 PMCid:PMC2565463.
http://dx.doi.org/10.1155/NP.2005.221
http://dx.doi.org/10.1155/NP.2005.221...
and biomechanical constraints3030. Burtner PA, Qualls C, Wollacott MH. Muscle activations
characteristics of stance balance control in children with espástico cerebral
palsy. Gait Posture. 1998;8(3):163-74.
http://dx.doi.org/10.1016/S0966-6362(98)00032-0
http://dx.doi.org/10.1016/S0966-6362(98)...
, is directly related to independent locomotion1212. Liao HF, Gan SM, Lin KH, Lin JJ. Effects of Weight resistence on
the temporal parameters and electromyography of sit to stand movements in
children with and without cerebral palsy. J Phys Med Rehabil. 2010;89:99-106.
PMid:20090426. http://dx.doi.org/10.1097/PHM.0b013e3181c55874
http://dx.doi.org/10.1097/PHM.0b013e3181...
. Therefore, in clinical practice, balance control training while standing
might represent a method by which children can gain independence in performing tasks
requiring locomotion.
This study also revealed that children with higher mean velocities of oscillation had
an increased dependence on others to perform self-care activities. The velocity of
CoP oscillation is a primary predictor of body stability in postural control
analyses and has been inversely correlated with the control of body segments in
space33. Chen J, Woollacott MH. Lower extremity kinetics for balance
control in children with cerebral palsy. J Mot Behav. 2007;39:306-16.
PMid:17664172. http://dx.doi.org/10.3200/JMBR.39.4.306-316
http://dx.doi.org/10.3200/JMBR.39.4.306-...
,
2828. Sobera M, Siedlecka B, Syczewska M. Posture Control development
in children aged 2-7 years old, based on the changes of repetability of the
stability indices. Neurosci Lett. 2011;491:13-7. PMid:21215293.
http://dx.doi.org/10.1016/j.neulet.2010.12.061
http://dx.doi.org/10.1016/j.neulet.2010....
. Therefore, increased velocities reflect reduced control over postural
responses, whether through neuromotor deficits or biomechanical changes3030. Burtner PA, Qualls C, Wollacott MH. Muscle activations
characteristics of stance balance control in children with espástico cerebral
palsy. Gait Posture. 1998;8(3):163-74.
http://dx.doi.org/10.1016/S0966-6362(98)00032-0
http://dx.doi.org/10.1016/S0966-6362(98)...
. Accordingly, the deficits in postural control observed in children with CP
result in an increase in postural instability while standing2323. Ferdjallah M, Harris GF, Smith P, Wertsch JJ. Analysis of
postural control synergies during quiet standing in healthy children and
children with cerebral palsy. Clin Biomech. 2002;17:203-10.
http://dx.doi.org/10.1016/S0268-0033(01)00121-8
http://dx.doi.org/10.1016/S0268-0033(01)...
, in which the vast majority of functional self-care activities are
performed.
In general, the results of the present study suggest that the difficulties
experienced by children with CP when controlling body positioning in space, which
result from deficits in body structure and function, influence other domains of a
child's health status and interfere with his/her activity levels and social
participation2626. Dos Santos AN, Pavão SL, Campos AC, Rocha NACF. International
classification of functioning, disability and health in children with cerebral
palsy. Disabil Rehab. 2012;34(12):1053-8. PMid:22107334.
http://dx.doi.org/10.3109/09638288.2011.631678
http://dx.doi.org/10.3109/09638288.2011....
.
By becoming more dependent on a caregiver to perform daily routine tasks and by experiencing limited mobility, these children have a limited ability to explore the environment around them and establish social ties with people outside of their families. The continued requirement for help when performing certain tasks prevents children from independently participating in many activities and causes them to become dependent on their caregivers even for social integration.
Because changes in postural control may determine functional changes, increasing postural stability should be a goal of physical therapy programs for children with CP, as physical rehabilitation can improve their level of functionality and thus yield increases in their levels of social interaction with their surrounding environment. Similarly, while considering the results of the present study and the broad and comprehensive definitions of an individuals health characteristics as advocated by the ICF, children with CP should be encouraged to more effectively participate in their own daily routine activities and to become as independent as possible to help them achieve greater postural stability while standing.
According to the new World Health Organization rules established by the ICF, clinical
practices should increasingly seek to address the health status of individuals in a
more broad and comprehensive manner rather than simply focusing on dysfunctions
related to body structure and function. Instead, clinicians should seek to emphasize
the impact that these deficits have on the activities performed by individuals as
part of their social participation1313. Beckung E, Hagberg G. Neuroimpairments, activity limitations,
and participation restrictions in children with cerebral palsy. Dev Med Child
Neurol. 2002;44:309-16. PMid:12033716.
http://dx.doi.org/10.1111/j.1469-8749.2002.tb00816.x
http://dx.doi.org/10.1111/j.1469-8749.20...
.
Therefore, given the relationship between postural control and the level of functional abilities in children with CP, more studies will be needed to determine the therapeutic approaches that will be most effective in promoting increased functionality and social participation in this population. It is believed that establishing this relationship will generate new directions for clinical practice and thus will guide treatment strategies for balance disorders that will help children to acquire specific functional abilities and establish independence from their caregivers.
Conclusion
In children with CP, postural control while standing has an important relationship with the level of functionality and thus establishes a direct relationship with the level of dependence on a caregiver. Therefore, the increased difficulty experienced by a child while maintaining a stable standing posture is related to their ADL performance and level of caregiver dependence.
Acknowledgements
The authors thank the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), São Paulo, SP, Brazil (2010/12594-4 and 2010/15010-3) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brasilia, DF, Brazil (136615/2011-2) for financial support.
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Publication Dates
-
Publication in this collection
18 July 2014 -
Date of issue
Aug 2014
History
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Received
27 May 2013 -
Reviewed
02 Jan 2014 -
Accepted
27 Feb 2014