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The Effects of Early Motor Intervention on Children with Down Syndrome or Cerebral Palsy: A Field-Based Study

Deitz-Curry, Johanna E. MS, PT

Departments: Critical Reviews of Current Research

MCP/Hahnemann University

Critical Reviews of Current Research : Manuscripts for this department should be sent directly to Ann F. VanSant, PhD, PT, Temple University, Department of Physical Therapy, College of Allied Health Professions, 3307 N. Broad Street, Philadelphia, PA 19140.

The Effects of Early Motor Intervention on Children with Down Syndrome or Cerebral Palsy: A Field-Based Study

by G. Mahoney, C. Robinson, and R. R. Fewell, Journal of Developmental Behavioral Pediatrics, 2001;22:153–162.

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Very little research that specifically addresses the results of motor interventions on motor outcomes in young children has been published. Motor interventions for children are not homogeneous. A variety of theoretical models of motor intervention, such as neurodevelopmental treatment (NDT), developmental skills models (DevS), sensory integration (SI), and conductive education, are mentioned in this article. Service models are also numerous and include individual treatment sessions, small groups, and consultation. Motor intervention can take place in clinical, educational, or home settings. The frequency of service delivery can range from once to several times a week to once a month or less. The intervention can be performed by a variety of professionals, such as a physical therapist, occupational therapist, early intervention teacher, or adaptive physical educator. Almost no research investigates how the differences in the method of service delivery affect motor outcomes. High-quality investigations are needed to inform personnel about better practice models for motor intervention with young children so they can make informed decisions about cost-effective and high-quality delivery of services.

The nature of the child’s motor problems can be classified either as an overall motor delay, which is frequently seen in children diagnosed with mental retardation (such as children with Down syndrome), or as a motor delay with substantial impairment in the formation and development of motor control, which is typically seen in children with cerebral palsy. The authors believe different treatment strategies are needed for different types of motor delays. The major goal for children with overall motor delay is “to enhance the rate of acquired motor skills and to prevent the occurrence of secondary problems.” Children with atypical patterns need an intervention that reduces muscle tone to allow the child to experience more typical movements as well as environmental and task modifications to allow the child to participate in everyday activities and routines.

Two routinely used motor intervention models used in early intervention and physical therapy programs are NDT and DevS. NDT involves handling a child with the goal of inhibiting abnormal tone to facilitate automatic reactions to promote normal development. This approach is used primarily with children who have cerebral palsy as well as children who have other motor problems, including hypotonia, which is seen in children with Down syndrome.

The purpose of this study was to investigate two motor intervention programs, NDT and DevS, on the development of young children with Down syndrome and cerebral palsy. There were four hypotheses: 1) Children who receive therapy will make significant gains in their rate of motor skill development regardless of type of disability or treatment approach; 2) children who receive NDT intervention will demonstrate greater progress in the quality of movement than the children who receive DevS intervention; 3) children who receive more motor intervention services (greater frequency of services) will demonstrate greater gains in motor development than children who receive services at a lesser frequency; and 4) children who are receiving services from providers who have specialized motor intervention training (eg, NDT, physical therapist/pediatric specialist, or physical therapy provider) will show greater improvement than children who receive services from providers with less specialized training.

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The 50 subjects in the sample were recruited from nine sites in six states. Forty-eight percent were boys. The average age was 14 months. Subjects were observed for a one-year period. The sample was ethnically diverse. Children were mostly from two parent families, and 12% lived in rural areas. Almost half of the mothers were employed outside the home.

Five sites provided primarily developmental skill motor intervention (DevS), and four sites used an NDT approach. The five DevS sites were comprehensive early intervention service programs, of which four were associated with university personnel preparation programs. Only 45% of the service providers at the DevS sites had formal physical therapy training, and 40% had NDT training. Of the four NDT sites, three were hospital-based clinics, and the other was a center-based early intervention program for children with motor disabilities. All service providers at the NDT sites had formal physical therapy training, and 77% were NDT certified.

The NDT sites had 28 children, 17 with cerebral palsy and 11 with Down syndrome. The DevS sites had 22 children, six with cerebral palsy and 16 with Down syndrome. Children began receiving services at an average age of 6.5 months. The children were more delayed in their rate of motor development than in their rate of cognitive development.

The motor function level for the sample was based on the Gross Motor Classification System for Cerebral Palsy. Ratings were based on gross motor function and ranged from 1 (least severe) to 5 (most severe). An experienced physical therapist rated the children using videotapes of each child’s initial visit. There were no significant differences in gross motor classification between treatment groups or by diagnostic category.

Children were assessed at the beginning of the study (pretest) at 14 months of age and after one year of intervention (posttest). For the posttest assessments, the Bayley Scale of Mental Development was used as an indicator of general development, and the Peabody Developmental Motor Scales were used as indicators of gross motor development. There were no significant group, treatment, or group-by-treatment differences on any of the measures.

Videotapes of the children in six positions (supine, prone, sitting, quad or weight-bearing, kneeling, and standing) and of their transitions into higher positions were made at the pretest and posttest data collection points to assess quality of movement. An adapted version of the Toddler Infant Motor Evaluation (TIME) was used to assess the quality of each child’s movement before and after the year of intervention. This was said to correspond to the emphasis of NDT intervention. Interrater agreement was 90% for each movement component. Seven dimensions of movement quality were assessed: mobility, atypical mobility, component analysis, transition analysis, hypertonicity, hypotonicity, and atypical positions. The authors used TIME raw scores as ratings for each dimension of movement quality.

All subjects received motor intervention services by early interventionists or physical therapists, who used the same treatment model and procedures outlined at the beginning of the study. Each site had a coordinator who managed recruitment and data collection. Project coordinators were on site at the beginning and end of the year of intervention and were available for contact throughout the year. Providers kept service logs for each subject; the logs contained data on the frequency and duration of services, the types of service provided, and other details of the sessions.

At the six-month point, mothers completed the Family Focused Intervention Scale (FFIS), a 39-item questionnaire that assesses family support. The scale addresses items concerning activities that help parents become involved in community-based services; information about the child’s health, developmental, and disability status; instructional activities; personal and family assistance; and resource assistance.

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The mean number of motor intervention sessions per year for each subject was 39.4 (SD 24). Children in the NDT group received more sessions than children in the DevS group, but DevS sessions were longer than NDT sessions. DevS sessions were provided mainly in the children’s homes, whereas NDT sessions were provided either in a clinic or classroom setting. DevS sessions were twice as likely to have parents and professionals in attendance than were NDT sessions. DevS sessions focused on children’s play and general motor activity and providing parents with specific recommendations for natural environment activities, whereas NDT sessions focused on specific motor skills and issues related to muscle tone or posture and alignment.

The mothers of children in the DevS group received more family support services as well as more information about the child, educational activities, and systems engagement than mothers of children in the NDT group. This result was derived using an analysis of variance of the data from the FFIS.

Proportional change indices were computed to determine how the children’s rate of motor development after one year of intervention compared with the rate of development at the beginning of the study. The data suggest that the rate of motor growth during intervention was consistent with the rate of motor growth at the onset of intervention. An analysis of variance was used to examine the effects of treatment model, diagnosis, or treatment model with diagnosis. The results lead one to conclude that children with Down syndrome and cerebral palsy achieve equivalent rates of growth during intervention, that the rate of development attained in the two treatment groups (NDT and DevS) was similar, and that neither treatment model had a different effect based on diagnosis. The authors concluded that the children’s rate of motor development after one year of intervention does not exceed their rate of growth at the onset of intervention.

A multivariate analysis of variance was used to examine the effects of treatment and diagnosis on changes in quality of motor performance using the TIME scores from the pretest to the posttest. The results showed a difference in the quality of movement between children with Down syndrome and children with cerebral palsy at both observation points. Children with Down syndrome were hypotonic, whereas children with cerebral palsy were hypertonic. Children with cerebral palsy had higher scores for atypical mobility and atypical positions. Neither of the two groups differed significantly in mobility scores. There were significant intervention effects for each dimension of movement. Regardless of the treatment model or diagnosis, quality of movement was rated higher after one year of intervention than at the beginning of the study. Children who received NDT intervention had the same level of improvement on all measures of quality of movements as children who received DevS intervention, leading to the conclusion that NDT was not more effective than DevS at enhancing quality of movement for children with cerebral palsy.

Regression models were used to evaluate factors that contributed to the rate of motor development after intervention. The rate of development at the pretest assessment was highly predictive of rate of development at the posttest assessment and did not differ according to diagnosis. Differences in specialized training of service providers (general interventionist, physical therapist, or physical therapist with NDT certification) did not contribute significantly to the children’s rate of motor development at the posttest assessment. The frequency of motor intervention sessions, not the rate of treatment, contributed to the rate of motor development. Children who received more motor intervention showed greater gains regardless of the type of intervention. The sample was divided into two groups based on intensity of treatment. The low-intensity group received an average of 19 motor sessions per year, and the high-frequency group received an average of 56 motor intervention sessions per year. The two groups showed no difference in rate of motor development at the pretest assessment, but they did differ at the posttest assessment. The low-intensity group rate of development was 17% less than expected (approximately five months’ gain in 12 months of intervention), and the high-intensity group was 14% greater than expected (approximately seven months’ gain in 12 months of intervention).

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This study was conducted to determine changes in motor functioning for children with disabilities in diverse and typical intervention sessions rather than in a controlled environment. The gains the young children made in motor development during motor intervention primarily reflected maturational effects rather than treatment effects. The first measurement of motor development was taken after the children had received at least six months of motor intervention, which may have exceeded the rate of maturational growth before intervention. In addition, there was no control group to compare the rate of motor growth for children who received treatment against children who had no motor intervention. However, specific motor intervention services neither reduced nor remediated children’s motor impairments regardless of treatment approach or specialized training of personnel delivering the motor intervention.

What did have an effect on the rate of motor development was the intensity of services. Children who received services at least once a week had a higher rate of motor growth than did children who received less frequent intervention. Additional research is needed to compare the effects of service frequency and intensity under similar treatment conditions to determine the optimal frequency of motor intervention to promote motor growth.

One argument proposed for the intensity effect was that it did not result from the treatment the child received but can be related to the commitment and determination of the parents to promote their child’s motor capabilities. It suggests that parental involvement may be the key to enhancing children’s development.

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Limitations and Implications

This study is commendable in that it seeks to provide answers concerning treatment models and best practice motor intervention for young children with movement disabilities. It studied practice in a variety of typical settings across a sample of children from diverse geographic and ethnic backgrounds. Objective data were systematically recorded, and reliability studies were performed to ensure consistency of information. The results provide food for thought and should stimulate further research in each of the areas studied, including the effect of treatment intensity on rate of motor performance, the effect of different treatment models in a variety of settings, and the influence of parent and caretaker participation in the motor sessions and its influence on motor growth.

There are several limitations to the study, a few of which the authors mention. The sample size was small, and no power analysis was used. The effects of treatment models or training of personnel may be small but significant, but with the small sample size this could have been missed. There were only six children with cerebral palsy in the DevS group, and most were mildly involved. The NDT group had 17 children with cerebral palsy, and most were moderately involved. Although statistically this did not make a difference, in practice there can be substantial differences. If the children who received a greater frequency of motor intervention services were the more motorically involved, this is very important because this group made the greatest gains in the rate of motor development with intervention.

With respect to the training of personnel providing the motor intervention, all providers in the NDT group were physical therapists, and most were certified in NDT. The services often occurred in a clinical setting in isolation from other professionals and with limited involvement of parents. Would there have been a more significant difference in the personnel providing the motor intervention if NDT intervention had occurred in the naturalistic settings as did the DevS treatment? This should be studied further to determine if the profession of the personnel providing motor intervention makes a difference in the rate of motor growth as well as in enhancing the parents’ understanding of their child’s disability and how to optimize the functional motor performance of their child.

The study used the Gross Motor Classification System for Cerebral Palsy to describe the level of motor functioning of the sample. This system is intended to be used with children who have cerebral palsy, but the authors used this scale to classify children with Down syndrome. This scale was not meant to be used for children with Down syndrome, and it has not been tested for reliability or validity with this diagnostic group. A different measurement instrument that has been found to be reliable across diagnostic groups, such as the PEDI or the WeeFIM, could have been used as a functional measure.

The NDT approach is defined in a very limited and antiquated sense by the authors. Current practitioners who use an NDT approach to treatment do not focus solely on muscle tone normalization or facilitation of the development of balance and righting responses. There is an emphasis on practicing motor skills with and without handling, modifying the environment to provide opportunities for learning, and giving information to the parents for carryover of activities in the home.

The authors also conclude that process-oriented approaches to motor intervention such as NDT may be flawed, but functional skills development training was no better at enhancing motor development. However, the fact remains that the NDT approach to treatment in this study often occurred in artificial environments without parents present. NDT involved facilitation of movements by the therapist. Service provided in a more natural environment allows the child to practice and explore while the therapist models behaviors and involves the parents or caregiver, who could learn strategies to incorporate practice into the daily life of the child in the family. Current research in the field of child development and motor learning has consistently emphasized that motivation, participation, activities that are functional and meaningful to the child and family, and practice are essential in enhancing motor development.

Is it the treatment approach used, the setting in which the motor intervention is provided, the training and skills of the person performing the intervention, the motivation of the child, the involvement of the parent or caregiver, the ability to practice what was learned, or a combination of all these factors that makes a difference in the rate of motor development for children with motor disabilities? Further research is needed to answer these questions, which the authors have started to address in this study.

Johanna E. Deitz-Curry, MS, PT, MCP/Hahnemann University

© 2001 Lippincott Williams & Wilkins, Inc.