Pelizaeus-Merzbacher disease

Background and Purpose. Physical therapists strive to promote children's motor function and the parents' abilities to interact with their children, thus aiming to positively influence the parent-child relationship. This study examined a model for provision of home-based physical therapy within the context of motor play on mother-child interactions and motor behaviors of children. Subjects. The subjects were 38 mothers and their children with motor delay, aged 6 to 34 months (X=18.8, SD=7.2), who were receiving center-based early intervention. Method. Children were ranked by motor development, using the Bayley Motor Scale, and assigned to either an experimental or control group. The experimental group received five home-based sessions of physical therapy. Conventional physical therapy strategies were incorporated into interactive play activities between mothers and their children. Both groups continued to receive their centered-based services. Mother-child interactions were videotaped before and after intervention and were analyzed using a modification of the responseclass matrix. Results. The mothers in the experimental group demonstrated an increase in appropriate holding of their children, whereas mothers in the control group demonstrated a decrease. The mothers in the experimental group became more directive, thus controlling their children's behavior, but they were not less positive or more negative when interacting with their children. Conclusion and Discussion. The integration of conventional physical therapy within the context of interactive play was well received and may promote generalization of motor skills during play without interfering with positive mother-child interactions. [Chiarello LA, Palisano RJ. Investigation of the effects of a model of physical therapy on mother-child interactions and the motor behaviors of children with motor delay. Phys Ther. 1998;78:180-194]

Key Words: Early int Family-focused care, Mother-child interaions, Pediatric physical therapy, Play.

Parent-child interaction is an important component of a family-focused approach to early intervention.l2 The parent-child relationship contributes to the child's development.3-9 In addition, parents and practitioners reported enhancement of parent-child relationship as an expected family outcome of early intervention. 10 In a meta-analysis of the efficacy of early intervention for children with disabilities, Shonkoff and Hauser-Cram" concluded that programs that targeted their efforts at both the child and the family appeared to be most effective. The positive influence of relationship-focused early intervention on mother-child interaction and child development has long been recognized.l2-25 A relationship-focused model of early intervention strives to enhance positive parentchild interaction and emphasizes that these interactions provide the foundation for a satisfying relationship as well as for the development of the child and the parents.l2,14 Intervention programs are designed to guide parents in understanding and responding to their child's behaviors, interests, and needs. Although positive parent-child interaction is considered part of state-ofthe-art pediatric physical therapy practice for young children with motor disabilities,2 the effectiveness of physical therapy in promoting parent-child interaction has not been investigated.26,27

There is evidence that a child's motor skill level influences mother-child interactions, particularly for children with motor disabilities.23-34 As a child's motor developmental age increases, physical contact decreases, maternal warmth and friendliness increase, and the child's responsiveness and clarity of cues increase during mother-child interactions.28-30 Children with motor disabilities have been reported as being less active participants during interactions with their mothers.231-33 Mothers of children with disabilities have consistently been reported to be more directive; however, mothers' activity level, responsiveness, and affect have been variable.28,29,31-34

Maternal directiveness refers to the mother's use of verbal and nonverbal controls to lead her child's behaviors during interaction. It is a complex phenomenon and may have both positive and negative implications.38 Maternal directiveness may be related to parent training models that emphasize the need for parents to teach their children developmental skills. Maternal directiveness, if provided with sensitivity to the child's needs, may help to foster the child's participation, interest, and development.38 If maternal directiveness, however, is coupled with insensitivity and a lack of warmth, then maternal control may inhibit a child's responsiveness and play. The implications of maternal directiveness on child outcomes have not been thoroughly investigated.

Parent-child interaction is a sensorimotor activity as well as a social-emotional experience.2 Motor control, sensory integration, and social skills are all components of parent-child interactions.39 Infancy has been described as the sensorimotor period of development.40 Young children use motor actions to engage the attention of their parents and to respond to requests and social interactions. Limitations on the ability to control the head and trunk, maintain positions, move in and out of positions, locomote, manipulate objects, and respond to sensory input can alter the dynamics of social interactions and may influence the degree to which a child can successfully interact with the environment.

To promote parent-child interactions, physical therapists need to provide intervention to the child to promote motor function as well as provide intervention to the parents to assist them in optimizing the child's abilities. Families have indicated that meeting their information needs regarding their child's disability, development, and care is a primary expectation of early intervention.lo Physical therapists provide parents with information on handling, positioning, and adaptive equipment that may assist the parents in the physical needs that arise when they interact with their child.

The Individuals With Disabilities Education amendments of 1991 (Public Law 99-457 and its reauthorization, Public Law 102-119) support the provision of early intervention services in the natural environment. With infants and toddlers, the context of learning is their home.41 The home environment fosters spontaneous use of skills by providing natural cues and reinforcement.42 Parents have rated home visits as the most helpful service component in early intervention,43 and mothers have reported a desire to participate in their children's play.44 Play is related to many areas of child development and is now accepted as an appropriate medium for teaching children new skills.42,45,46

We propose that a functional and meaningful model of service delivery is one that focuses on enhancing a child's motor abilities and performance within the context of mother-child interactions during play. Our model is based on the following concepts: (1) Improvement of sensorimotor function may foster a child's ability to participate more actively during parent-child interactions, (2) providing parents with information on their child's sensorimotor abilities enables them to adapt their expectations and interactions to fit the child's developmental abilities and functional needs, (3) home environments foster spontaneous use of motor abilities by providing natural cues and reinforcement,42 and (4) play is an effective medium for both parent-child interaction and therapeutic intervention.

The purpose of our study was to test our model in a preliminary fashion by examining the effects of homebased physical therapy provided in the context of motor play on mother-child interactions and the motor behaviors of children with motor delay. In addition, we wanted to explore maternal satisfaction with the home-based physical therapy intervention. An experimental and control group design was used in which children receiving early intervention were randomly assigned to either receive home-based physical therapy (experimental group) or not receive home-based physical therapy (control group). We hypothesized that the change in occurrence of behaviors from the preintervention assessment to the postintervention assessment would be greater for the experimental group than for the control group for the following behaviors: (1) children's motor behaviors during play with their mothers, (2) mothers' behaviors to promote the occurrence or quality of their children's motor behaviors during play, and (3) mothers' and children's pleasant reciprocal interactions. In addition, we hypothesized that the mothers of children in the experimental group would report satisfaction with the intervention program.

Method

Subjects

The subjects for this study were 38 mothers and their infants and toddlers, aged 6 to 34 months (X=18.8, SD=7.2), who were enrolled in early intervention programs. None of the children in the study were receiving home-based physical therapy when the study was begun. Twenty-six children were receiving center-based physical therapy, and 12 children (5 children in the experimental group and 7 children in the control group) were not receiving any physical therapy services. All mothers signed an informed consent form. Each child had a documented motor delay, no major visual or auditory handicap, and a cognitive level of at least 4 months, including being able to demonstrate a social response to people. Each child had a Psychomotor Developmental Index (PDI) of less than 73 (greater than 1.5 standard deviations below the mean PDI for their age) on the Motor Scale of the Bayley Scales of Infant Development.47 Thirty-one children had a PDI less than 50, which is greater than 3 standard deviations below the mean for children without motor delays. The children were unable to ambulate independently when the study was begun. Nine children (5 children in the experimental group and 4 children in the control group) had a diagnosis of Down syndrome, 12 children (6 children in each group) had cerebral palsy, and 2 children (both in the experimental group) had myelomeningocele. The remaining 15 children demonstrated delayed motor development and had one or more of the following conditions: developmental delay, infantile spasms, hydrocephalus, myotonic dystrophy, deletion of chromosome 9, agenesis of the corpus callosum, prematurity, cytomegalovirus, and Pelizaeus-Merzbacher disease.

The children in the study were recruited from eight early intervention programs. In an attempt to ensure that the groups were comparable on motor development and prior intervention, children were assigned to experimental and control groups in the following manner. All children recruited from a particular center were listed by rank order of motor developmental age using the Bayley Motor Scale.47 The first child on the list was randomly assigned to the experimental group or the control group, and the remaining children were then alternately assigned to each group. In this manner, half of the children recruited from a particular center were in the experimental group and half of the children were in the control group.

The demographic data for the experimental and control groups are presented in Table 1. Statistical analyses revealed that the two groups did not differ on these characteristics. Families of children in the experimental group had a median socioeconomic status score of 51, as compared with a median socioeconomic status score of 42 for families of children in the control group (P=.068). The median scores for the families in both groups, however, were in the same social stratum (AB Hollingshead, unpublished research).

Protocol

Prior to group assignment, all subjects received a preintervention assessment in their home. The mother and child were videotaped during 12 to 15 minutes of free play. Mothers were given the following standardized instructions: "I would like for you to play with your child as you usually do at home. You can use whatever toys you or your child likes, but you do not have to use toys if you prefer other games or activities. Feel free to use any adaptive equipment for positioning, and you can play in any positions you and your child usually use for play. I would like to request that other family members not be in the room during the videotaping because it may distract you and your child from playing. Because I am interested in how mothers and children interact during playtime, I will not participate in the interaction. Before or after the videotaping, I will answer any questions you may have."

The decision not to use a standardized set of toys was based on the primary investigator's (LAC's) pilot work. When a set of toys were provided, mothers often felt compelled to have their children play with the variety of toys provided and thus frequently directed their children from one activity to another. The purpose of the assessment was to examine how a mother and child routinely play together in their home environment. The choice of play materials was thus left to the mother and child. In addition, Mash and Terdal48 reported that although variations in play materials may prompt different kinds of play interaction, which in essence was part of the intervention process, the social content and structure of the mother-child interaction was a more salient feature than the play materials.

After the observation session, the mother was given the Maternal Observation Interview49 to complete. The Maternal Observation Interview is an 11-item interview schedule designed to assess a mother's reactions regarding the validity of the observation session. The mother was asked to ascertain how the observed interaction compares with her usual behavioral style and to report any behavioral occurrences that were not representative of typical patterns. In one instance, the Maternal Observation Interview indicated that the mother believed the observation session was not representative of her usual interactions with her child. A second mother-child observation session was conducted, the mother indicated that the session was representative of their routine play time, and the responses from the second session were used for data analysis.

At the end of the initial session, the Bayley Motor Scale47 was administered to the child. Interrater reliability between the primary investigator and another pediatric physical therapist was established on five children prior to the start of the study and on two children during the data collection phase of the study. The intraclass correlation coefficient (ICC[2,1]) for the total raw score was .99.

During the postintervention assessment, mother and child pairs in the experimental and control groups were again videotaped in their home during a 12- to 15-minute free-play session. A modified version of the Client Satisfaction Questionnaire5o was used to assess the degree of maternal satisfaction with the experimental physical therapy intervention program. Larsen et al5o reported that the original scale had a high degree of internal consistency, as evidenced by an alpha coefficient of .93. The questionnaire was modified to reflect the components of the program. The questionnaire was used to determine the consumers' perception of how they benefited from the developed model for intervention. With a family-focused framework, consumer feedback and collaboration were essential components of the study to confirm whether the model was meeting the needs of the mother and the child. The parent satisfaction questionnaire was left with the mothers of children in the experimental group, who were asked to complete the questionnaire anonymously and to return it in a preaddressed and stamped envelope to the primary investigator.

Physical Therapy Interventions

During the study, all subjects continued to receive early intervention services as designated by their respective Individualized Family Service Plans. Through a questionnaire, the therapists from the centers indicated that enhancing mother-child interactions through play was not the explicit focus of the center-based therapy sessions. The presence and participation of the mothers and the format and availability of physical therapy services in the center-based programs were variable, depending on the staffing and philosophy of the early intervention programs.

In our study, the experimental group received weekly home visits for 5 weeks from a pediatric physical therapist (LAC). We believed that five weekly sessions was an appropriate intensity to provide the mothers and their children with guidance in their motor play that addressed the children's current needs. The short-term intervention for the experimental group had a specific focus that was unique compared with the center-based services that all the subjects were receiving. The emphasis was on collaboration with the mothers to identify enjoyable interactive motor play activities in the home and to provide recommendations for incorporating therapeutic strategies into interactive play. The desired effect of the intervention was enhancement of the interactive play process between mothers and their children.

Appendix 1 delineates the components of the experimental intervention model. Each intervention session lasted approximately 1 hour. During the first intervention visit, the physical therapist and the mother discussed the child's strengths and needs, the concerns and priorities of the mother, and the intervention plan. This discussion included an exchange of information on both the child's motor status and mother-child interactions. The session was informal, allowing the therapist, the mother, and the child an opportunity to get to know one another and to establish rapport.

Physical therapist intervention was individualized. The mother was present for the sessions and was invited and encouraged to participate in the activities. The mother's level of involvement in the session was left up to the mother. Conventional physical therapist interventions were incorporated into play activities. Therapeutic techniques included active range of motion, weight bearing, strengthening and endurance activities, use of prompts, and guiding movement. Other activities to enhance motor function included practice of functional motor skills and environmental adaptations. Instruction in positioning and handling techniques was provided by the pediatric physical therapist (LAC).

The play activities were selected in an effort to enhance gross motor and fine motor function. The intervention was designed to structure the home setting to provide movement opportunities. Activities were not restricted to play with toys or objects but also included simple games emphasizing play with motion and language. Typical play activities in a standing position included moving to the music of popular children's singing games such as "Monkeys Jumping on the Bed," "Ring Around the Rosy," and "Musical Chairs"; a sit-to-stand transition during "The Kids on the Bus"; and choo-choo train pretend play. Recommendations were made to modify equipment, articles, or toys found in the home.

Throughout each session, the therapist demonstrated and provided the mother with opportunities to participate in positive interactive behaviors such as allowing the child time to respond, providing the child with choices, praising and encouraging the child's efforts, selecting developmentally appropriate activities, and following the child's direction. The therapist attempted to generate a relaxed and enjoyable atmosphere to enhance the interpersonal aspects of the interaction. The mother and child were provided with positive reinforcement and ongoing feedback regarding the child's motor function and the mother's and child's interactive behaviors. These strategies reflect the principles and guidelines proposed by several leaders in early intervention.6,14,21,51,52

Procedural Reliability

Procedural reliability was examined during the study to determine whether the assessment and intervention procedures were performed in the intended manner. The second author observed one preintervention assessment and four intervention sessions, one of which was an initial intervention visit. A checklist completed during each observation indicated that the therapist completed 100% of the outlined steps developed from the intervention model (Appendix 1 ) during a preintervention assessment, an initial intervention visit, and three subsequent treatment visits.

In addition to completing a checklist of the outlined procedures, information on the frequency of key elements of the intervention was also determined. Procedural reliability results indicated that treatment procedures were consistent with the described method. Mothers participated in the play activities during 60% of the observed session. Children were involved in motor activities during 65% of the observed session. The therapist provided information during 15% of the observed session, promoted the child's motor skills without handling during 41.7% of the observed session, and promoted the child's motor skills with handling during 18.3% of the observed session. The context of the sessions was interactive play during 61.7% of the observed session.

Measurement Tool

The following dependent variables were defined prior to data collection: (1) the child's voluntary physical behavior, (2) the child's changes in position, (3) the child's locomotion (eg, creeping, cruising), (4) maternal promotion of the child's motor skills (eg, providing verbal cues, setting up equipment), (5) the mother's use of therapeutic positioning, (6) maternal holding, (7) the child's summary measure, which was a combination of the child's positive, interactive, and voluntary physical behaviors, and (8) the maternal summary measure, which was a combination of maternal positive and interactive behaviors and promotion of the child's motor skills. The child's voluntary physical behavior, changes in position, and locomotion were used as an index of the child's motor behaviors during play with the mother. Maternal promoting of the child's motor skills, use of therapeutic positioning, and holding were used as an index of the mother's promotion of the occurrence or quality of her child's motor behaviors during play. Several behaviors were combined to form the summary measures, which were used as an index of pleasant reciprocal interactions.

Mother-child interactions were measured from the videotapes using the response-class matrix (EJ Mash, L Terdal, K Anderson; unpublished coding manual),5 an interval recording observational method. The matrix was used to record the proportion of intervals in which verbal and nonverbal interactive behaviors occurred before and after intervention. The response-class matrix was modifled to reflect the nature of the study. The behaviors measured were chosen based on the original matrix, studies of mother-child interactions with children with motor delay,25,28,31,32,54 and a philosophy of pediatric physical therapy.' The child behaviors that were measured were negative, solitary, interactive, positive, physically directed, and voluntary physical behaviors. The maternal behaviors that were measured were negative, solitary, interactive, positive, and directive behaviors and promoting the child's motor skills. Definitions of the child's and mother's behaviors that were measured are provided in Appendix 2.

An independent observer who was unaware of group assignment recorded the behaviors from the videotapes. Each videotape was divided into 10-second intervals, marked by a time signal on the videotape and an audiotape. For each interval, the observer viewed and noted three behaviors: the mother's first (antecedent) behavior, the child's response, and the mother's next (consequent) behavior. This standard procedure enabled the researchers to examine behaviors in context. The observer noted the first mother-child-mother interaction sequence that occurred during each 10second observation segment. If an interval could not be noted due to obstruction of view, the interval was considered invalid for data collection. The first valid 60 intervals (10 minutes) were used for data analysis.

General rules for scoring the behaviors were as follows. If either the mother or the child performed several behaviors in succession, the behavior closest in time to the corresponding behavior of the other member of the dyad was noted. If a nonverbal behavior and a verbal behavior occurred simultaneously, the verbal behavior was noted. The original coding scheme of the responseclass matrix reflected general classes of behaviors as opposed to discrete behaviors (EJ Mash, L Terdal, K Anderson; unpublished coding manual). We were interested in two specific behaviors: maternal promoting of a child's motor skills and the child's voluntary physical behavior. If a behavior met the definition for one of these two specific behaviors, it was noted as such and was not noted as an interactive category behavior.

The noted behaviors were recorded with two matrices. The first matrix was used to record the mother's first (antecedent) behavior and the child's response. The second matrix was used to record the mother's behavior consequent to the child's response. In total, 120 maternal behaviors and 60 child behaviors were recorded.

In addition to recording the behaviors listed in the matrix, a tally of the following four behaviors was kept: the child's changes in position, the child's locomotion, the mother's use of therapeutic positioning, and maternal holding. A distinction was made between changes in position that were performed independently by the child, with participation by the child but requiring the assistance of the mother, or by the mother with the child totally dependent. This distinction was made to reflect opportunities for active movement by the child. A distinction was also made between therapeutic and nontherapeutic holding to reflect incidences in which physical contact may be beneficial to the child's motor needs and enhance the interaction. A tally was recorded if a behavior occurred any time during each of the 60 10-second intervals. Definitions of these behaviors are provided in Appendix 2. A sample recording sheet is provided in Appendix 3.

Following the guidelines of the coding manual, the primary investigator and the independent observer participated in 26 hours of collaborative training. Videotapes of interactions during free play of mothers and their children with motor delays who were not subjects in the study were viewed. An additional 14 hours of observation and interval recording was used to determine reliability. Prior to the start of the study, interrater reliability in scoring the response-class matrix was established between the independent observer and the primary investigator. Reliability was analyzed by occurrence agreement for each maternal and child behavior that was to be used for analysis in this study. Occurrence agreement of 80.1% was achieved for the maternal category "mother promotes the child's motor behavior." Occurrence agreement for the other categories ranged from 93.1% to 98.8%. Interrater reliability was rechecked during the study using four observations. Occurrence agreement for these observations ranged from 93.3% to 100%.

Data Analysis

The measurement of each dependent variable was expressed as a proportion of the total number of recorded behaviors. The total number of maternal behaviors was 120, and the total number of child behaviors was 60. The measurement of the four dependent behaviors that were tallied (child's changes in position, child's locomotion, mother's use of therapeutic positioning, and maternal holding) was reported as a proportion, with the total number of intervals equal to 60. For example, if maternal promoting of the child's motor skills was counted on the response-class matrix for 20 of the 120 recorded behaviors, then the occurrence of this behavior would be expressed as the proportion .17.

For each dependent variable, a two-factor (group x time) analysis of variance for repeated measures on the second factor was used to analyze group differences in child and mother interactive behaviors. The group X time interaction was examined to determine whether there was a differential change between the two groups. An alpha level of .05 was used for all analyses. This decision increased the risk of a Type I error because multiple tests were performed. Because this research was exploratory in nature, that is, to determine which aspects of mother-child interaction may be influenced by physical therapy, we did not believe that a correction factor was necessary. All statistical analyses were carried out using the SPSS/PC+ version 2.0 (1988) software program.

Results The change in the occurrence of the child's voluntary physical behaviors, changes in position, and locomotion between the preintervention and postintervention assessments did not differ between the experimental and control groups (Tab. 2). Although the F value for the interaction term (F=3.76; df=1,36; P=.06) did not reach the alpha level (P=.05), children in the experimental group changed positions an average of 8.7 more intervals at postassessment than children in the control group did.

Mothers of children in the experimental group and mothers of children in the control group did not differ in their change in the proportion of behaviors during which they promoted children's motor skills between the preintervention and postintervention assessments (Tab. 3). A child's voluntary physical behavior followed maternal promoting of motor behavior greater than 70% of the time. Mothers of children in the experimental group and mothers of children in the control group did not differ in their change in the proportion of intervals in which they used adaptive positioning between the preintervention and postintervention assessments. An interaction, however, was found for maternal holding (F=4.69; df=1,36; P

The change in the interactive summary measure scores between assessments did not differ for the children in the experimental and control groups (Tab. 4). Children in both groups demonstrated pleasant, reciprocal interactions in an average of at least 84% of the play intervals. Negative, solitary, and physically directed behaviors collectively were observed in an average of less than 17% of the play intervals.

The change in the interactive summary measure scores between assessments differed for the mothers of the children in the experimental and control groups (F=9.95; df=1,36; PC.O1) (Tab. 4).

The interactive summary measure score decreased from 77.2% to 66.2% for the mothers of children in the experimental group and increased from 72.5% to 77.2% for the mothers of children in the control group. To clarify this finding, five additional two-factor (group X time) repeated-measures analyses of variance were performed to determine the specific behaviors where the change in frequency differed between the two groups (Tab. 5). From the preintervention assessment to the postintervention assessment, the mothers of children in the experimental group demonstrated an increase in directive behaviors from 21.4% to 33.1% and the mothers of children in the control group demonstrated a decrease from 26.1% to 21.6% (F=11.3, df=1,36; P

Fifteen of the 19 mothers of children in the experimental group returned the Client Satisfaction Questionnaires, a return rate of 79%. The mothers indicated that they were very satisfied with the services they received and that they believed the services addressed their needs (Tab. 6). They commented that the communication between the therapist and themselves was effective and provided them with an understanding of play. The mothers expressed their beliefs about how physical therapy positively influenced both their interactions and their children's interactions during mother-child play. Overall, the mothers expressed that both they and their children enjoyed the program.

Discussion

The purpose of our study was to examine, in a preliminary fashion, a model for provision of home-based physical therapy within the context of motor play. Although our eventual aim is to determine whether this treatment model enhances development of motor function in young children with motor delays, the first step was to examine the immediate effects on mother-child interactions and children's motor behaviors. Our model is based on the assumption that an intervention provided within a family-focused framework and in the context of play would support and enrich the child's natural environment and ultimately enhance development of motor function. The intervention was positively received by mothers and children in this study. Although our hypotheses were not fully supported, the findings indicate that mothers can promote physical activity through play while being sensitive to positive social interactions.

Statistical analysis did not support our hypothesis that children in the experimental group would achieve a greater change in the occurrence of changes in position during play than children in the control group would achieve. Further investigation may be warranted to determine whether physical therapists can be influential in teaching mothers how to integrate gross motor activities and movement transitions into play. In our study, the children in the experimental group changed positions an average of 8.7 more intervals than did the children in the control group. Mothers of children in the experimental group were more apt to include gross motor play in a variety of positions. On the Client Satisfaction Questionnaire, mothers commented that they developed an awareness of the use of play to promote their children's motor abilities. This added practice and repetition may be clinically important in the generalization of motor skills.

Despite the emphasis on motor behaviors during playful interactions, no change was noted in the proportion of voluntary physical behaviors between the preintervention and postintervention assessments. Two factors may have contributed to this result. First, the proportion of voluntary physical behaviors was high when the study began. For the most part, children were active participants. This finding is in contrast to many reports that children with disabilities are passive.2832,33 Second, this category was general and included any motor response. In retrospect, the definition for voluntary physical behaviors may have been more appropriate for detecting change in children with severe motor impairment who demonstrate a paucity of movement. Although the children in our study had delayed motor development, they all demonstrated some method of self-initiated movement during play. A detailed rating scale would have been needed to measure qualitative changes and the success of the children's movements during play.

The mothers of the children in the experimental group did not demonstrate a greater change in the proportion of behaviors that promoted their children's motor abilities or in the proportion of use of adaptive positioning compared with the mothers of the children in the control group. In comparison, Hanzlik19 found an increase in the use of adaptive positioning by mothers of children with cerebral palsy after 1 hour of maternal instruction on interactive techniques and positioning. In our study, the families had participated in an average of 1 year of early intervention, and a ceiling effect may have occurred.

Our results support the role of the physical therapist in providing instruction to mothers on therapeutic handling to promote their children's play and movement. The mothers of the children in the experimental group demonstrated an increase in the proportion of therapeutic holding between assessments, whereas the mothers of the children in the control group demonstrated a decrease. This finding appeared to be a result of the strategies provided to the mothers to give their children guidance in supported positions. The mothers successfully provided support for their children that enabled them to play in appropriate positions to promote gross motor activity. The mothers of the children in the control group showed a higher proportion of holding during the preintervention assessment than during the postintervention assessment. This finding may have been attributable to a few mothers holding their infants for a large percentage of the play session. This possibility is substantiated by the large variability in the control group's holding scores.

The results of our study suggest that our treatment model, which integrated therapeutic activities into play and social interactions, was well received by the children and their mothers. The finding that the children's interactive summary measure did not differ between the two groups during the postintervention assessment can be interpreted as a positive finding. The children in both groups rarely demonstrated negative or solitary behaviors during either assessment. Unlike the results of earlier studies in which mothers displayed negative behaviors and children cried during mother-child therapy sessions,29 ,55 the children and mothers in our study were positive and interactive during play activities in which the mothers promoted and directed their children's motor behaviors.

We believe the finding that the mothers of children in the experimental group became more directive after the 5-week period than the mothers of children in the control group may represent a desired effect of physical therapy, although that was not our view when the study began. The connotation of maternal directiveness that we adopted from research on mother-child interactions may not be directly applicable for children with motor delays. A focus of early intervention is providing information and guidance to parents on how to enhance their child's development. As parents become more knowledgeable about how play fosters development, they are likely to be more directive when interacting with their children during play. In our study, the increase in the directiveness of the mothers of children in the experimental group did not appear to have a negative effect on the children, who were still active and pleasant participants. Rather, the increased directiveness appears to reflect (1) the increased ability of the mothers to use play activities as therapeutic strategies, (2) the children's need for directiveness to participate in play activities that were developmentally challenging, and (3) the mothers' desire for their children to perform optimally. Mothers of children in the experimental group learned to set up play situations to encourage creeping, pulling the stand, and cruising and used verbal commands to direct the children to the activity instead of allowing the children to explore freely. Our new perspective is supported by Marfo35 and Tannock,37 who stated that maternal directiveness, warmth, sensitivity, and responsiveness are not incompatible and that maternal directiveness may serve to encourage child participation.

Controversy still exists over the significance of maternal directiveness. We believe that therapists should be aware that their interventions may foster maternal directiveness and place a greater emphasis on motor performance and less of an emphasis on interactive play. We contend that therapists need to consider maternal directiveness in the context of a mother's affective behaviors and how this interactive style enhances or limits a child's responsiveness. Further research is needed to determine the effect of physical therapy on fostering maternal directiveness and to explore the interrelationships between maternal directiveness and responsiveness and their influence on the child.

The response-class matrix did not provide information on two important characteristics of maternal interactive behavior: mothers' developmental awareness and sensitivity. Furthermore, mothers and children in both groups appeared to have demonstrated effective interaction abilities during the preintervention assessment. This finding was not anticipated, and the measuring tool may not have been sensitive enough to document the mothers' incorporation of therapeutic strategies into pleasant play interactions. Most importantly, limitations in internal validity need to be emphasized. Even though a control group was used in the design, both groups were receiving center-based early intervention and may have been exposed to some aspects of our intervention model. While not examined, the center-based model of early intervention may have positively influenced the children and mothers in the study. In addition, it is acknowledged that the amount of therapy was a confounding variable that was not controlled. The experimental group received five intervention visits which were not balanced by additional services for the control group.

Conclusion

A model for provision of home-based physical therapy within the context of interactive play was well received by the children and mothers in this study. The results of the influence of this model on children's motor behaviors during play with their mothers were inconclusive. Children in the experimental group changed positions an average of 8.7 more intervals than did children in the control group. Children in the experimental group, however, did not demonstrate a greater change in overall voluntary physical behaviors, as was hypothesized. The proportion of voluntary behaviors for both groups was high during the preintervention assessment, which is in contrast to reports that children with disabilities are passive.29,33,34 Additionally, the definition of voluntary physical behaviors was too general for the subjects in this study, all of whom demonstrated some method of selfinitiated mobility.

The results of the influence of this model on mothers' behaviors to promote their children's motor behaviors were inconsistent. Mothers of children in the experimental group demonstrated an increase in therapeutic holding but did not demonstrate a greater change in overall behaviors to promote their children's motor behaviors. Mothers of children in both groups were already promoting their children's motor behaviors at the time the study was begun.

The hypothesis that children in the experimental group and their mothers would demonstrate a greater change in pleasant reciprocal interactions was not supported. Children in both groups rarely demonstrated negative or solitary behaviors at either the preintervention assessment or the postintervention assessment. In comparison with the mothers of children in the control group, the mothers of children in the experimental group demonstrated an increase in directiveness, but they were not less positive or more negative when interacting with their children. The directiveness appeared to reflect the mothers' abilities to incorporate therapeutic strategies into play and to direct their children to participate in play activities that were developmentally challenging.

Additional research is necessary to examine whether our treatment model is effective in promoting the generalization and practice of motor skills during play without interfering with positive reciprocal interactions. A next step is to determine whether short-term, home-based intervention results in carryover of parent-child motor play interactions as part of daily routines. This evidence is needed prior to investigation of whether a familyfocused, ecological model of physical therapy is effective in promoting the development of motor function in children with motor delays.

Acknowledgments

We thank advisory committee members Dr Susan K Effgen, Dr Susan R Harris, Dr Louisa Seraydarian, and Dr B Janet Hibbs for their assistance and support and Marcia Levinson for scoring the videotapes. We are grateful to the staff of the early intervention programs for their assistance in recruitment of subjects. This research could never have been completed without the special families who welcomed us into their homes.

SPSS Inc, 444 N Michigan Ave, Chicago, IL 60611.

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LA Chiarello, PhD, PT is Assistant Professor, Department of Physical Therapy, Philadelphia College of Pharmacy and Science, 600 S 43rd St, Philadelphia PA 19104 (USA) (Lchiare@pcps,edu). She was a doctoral student at Hahnemann University Philadelphia, Pa, at the time of th study, Address all correspondence to Dr Chiarello.

RJ Palisano, ScD, PT is professor, Department of Physical Therapy, Allgeheny Unicersity of the Jealth Sciences, Philadelphia, Pa and Co-investigator, Neurodevelopmental Clinical Research Unit, McMaster University, Hamilton, Ontario, Canada

This study was presented as a platform presentation at the Combined Sections Meeting of the American Physical Therapy Association; Feburary 2-6; 1994; New Orleans La.

The study was approved by Hahnemann University Institutional Review Board.

This study was supported by a leadership preparation grant (H029D00005) from the US Department of Education, Office of Special Education and Rehapbilitation Service, to Hahnemann University and by a doctoral student grant from the Foundation for Physical Therapy Inc.

This article was submitted August 30, 1996 and was accepted September 3, 1997

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