Ustad, Tordis PT, MSc; Sorsdahl, Anne B. PT, MSc; Ljunggren, Anne E. PT, PhD
Cerebral palsy (CP) is the most common neurologic developmental disorder, occurring in 2 or 3 per 1000 live births.1 CP describes a group of permanent disorders of development of movement and posture secondary to nonprogressive pathology of the immature brain. The motor disorders are often accompanied by disturbances of sensation, cognition, communication, perception, behavior, epilepsy, and secondary musculoskeletal problems.2 The motor disorders include delay in movement onset, poor force production and poor timing of force generation, difficulties with antigravity postural control, and increased cocontraction.3 The delay in gross motor skill development is well documented.4–6 The postural dysfunction in CP is the reduced capacity to modulate postural activity in specific situations and increased antagonist coactivation.7 Unlike children developing typically, infants with unilateral CP do not develop direction-specific activity in the trunk until 15 months of age.7,8
Motor learning is defined as a set of processes associated with practice or experience that leads to relatively permanent changes in the ability to produce skilled action.9 As a result of central nervous system dysfunction, children with CP have specific constraints to movement, resulting in reduced experience and variation in motor activities.10 Recent studies on motor control in children with CP indicate that problems with motor planning may be just as limiting for motor learning as problems related to movement execution.10–13
Because of central nervous system plasticity, infants with CP have potential for enhanced function.14 Plasticity is defined as the brains’ ability to learn, remember, and forget as well as its capacity to reorganize and recover from injury. Synaptic connections are refined through activity.15 Spontaneous plasticity can be potentiated and shaped by activity and the use of an enriched environment and appropriately targeted training strategies likely potentiate the capacity of the brain to compensate for lesion-induced deficits.16 The presence of definitely abnormal movements in infants aged 2 to 4 months puts these children at such a high risk for CP that it warrants physiotherapeutic intervention.17 Given that experience is important in shaping the function of the developing nervous system,14 and that practice and task-specific training is essential in motor learning,10 physiotherapy should have an effect on motor outcome in children with CP.
However, the effect of early intervention on motor development for infants is inconclusive,18,19 and there are few studies that document physiotherapy intervention for infants with CP. Studies measuring the effect of physiotherapy for slightly older children with CP are also inconclusive.20–22 Treatment intensity, what treatment approach is the most effective, and what is the optimal age for treatment are yet to be decided.14,23,24 Trahan and Malouin25 found that short periods of daily physiotherapy, alternating with longer rest periods, seemed to optimize the effect of motor training in 5 children with severe CP, mean age 22.6 months. Christiansen and Lange26 found identical outcomes between groups, when they organized physiotherapy in 2 different ways for 25 children with CP, mean age 3 years. No treatment approach is yet shown to be superior to others. Basic factors in all therapy intervention should be active participation, opportunities for practice, and practicing of meaningful goals.14
The purpose of our study was to gain further knowledge about the effect of physiotherapy in infants younger than 1 year who were diagnosed with CP. We hypothesized that periods of intensive physiotherapy (5 times per week for 4 weeks) would accelerate acquisition of gross motor functional skills to a greater extent than standard care.
The children were recruited from a university hospital in Trondheim from June 2003 until August 2005. The inclusion criteria were children aged 6 to 12 months, with a strong probability of having CP due to abnormal motor development, and living within a 30-minute drive from the hospital. Children with other diagnoses and children who received orthopedic surgical interventions, botulinum toxin A injection, or alternative treatment were excluded. Five pairs of parents gave written consent to take part in the study. The Regional Committee for Medical Research Ethics approved the study. Notification was sent to the National Data Inspectorate of Norway.
The 5 children were between 5 months 3 weeks and 9 months corrected age (Table 1). Four were recently diagnosed as having CP. In Child 5, the diagnosis was not yet confirmed at the time of inclusion because of few clinical indicators. The diagnosis was confirmed when the child was 2 years old. Four children had signs of unilateral CP and 3 were born premature. Except the motor disorder, none of the children had other known disturbances or developmental delays. The children were preliminarily classified according to the Gross Motor Function Classification System (GMFCS).27 The GMFCS classifies children with CP according to level of severity, ranging from I to V, level V being the most severe. Three of the children had a local physiotherapist whom they had consulted a few times before taking part in the study.
A single-subject, multiple-baseline, withdrawal design was used (ABABA).28 The primary function of single-subject designs is to perform a systematic comparison of the baseline period (A) and the intervention period (B) for one individual. The individual’s performance is monitored at regular intervals to investigate whether treatment is producing a therapeutic change.29 An ABA design will reflect an effective treatment by improvements during the intervention phase and retention in the next phase A. This design allows for documentation of carry-over effects after intervention is conducted,30 thus a withdrawal design is useful in studies of skill acquisition.31 The major advantages of multiple-baseline designs are that they control for major threats to internal validity, especially history.31
The multiple-baseline across subjects design was nonconcurrent starting at different times for the 5 children. The baseline period (A1) varied between 4 and 16 weeks. Periods A2 and A3 were set to 8 weeks. During periods of A (physiotherapy as usual) the children received physiotherapy in their homes, from their local physiotherapists. The amount of therapy varied. Two children received physiotherapy once a week or once every second week, consisting of parent instruction on how to assist their child with gross motor activities. Two children had not been referred to a physiotherapist yet, and 1 child had a pause in therapy because of the summer holiday. Periods of B (B1, B2) comprised 4 weeks with one daily session of therapy (5 days per week; 3 sessions at the hospital and 2 sessions at home). Figure 1 provides a schematic view of the research design.
The children were assessed every fourth week using the Gross Motor Function Measure (GMFM).32 The GMFM is a criterion-referenced activity level outcome measure, designed to evaluate changes in gross motor function in children with CP from 6 months of age whose motor skills are below those of a 5-year-old child without any motor disability.33 Extensive research of the test’s psychometric properties suggests high validity and reliability.33–36 The items are grouped into 5 dimensions of basic motor functions: (1) lying and rolling, (2) sitting, (3) crawling and kneeling, (4) standing and walking, and (5) running and jumping. There are 2 versions of the GMFM: the GMFM-88 and the GMFM-66. While the GMFM-88 gives credit for each new movement, the GMFM-66 gives credit for each new skill.32 By using the GMFM-66, it is possible to calculate a total score without administrating all items. The GMFM-66 is more suited for research purposes, as the items are converted to an interval scale. However, because of the young age of the children, and since GMFM-66 only measures 4 items in the dimension of lying and rolling, both versions of the GMFM were used in this study.
One blinded assessor, not knowing whether the children had received intensive therapy or not, assessed the children. The therapist had access to one set of previous test scores. All tests were recorded by a handheld camcorder.
During each period B1 and B2, the children were offered intensive physiotherapy. We defined intensive physiotherapy as 1 hourly physiotherapy intervention, 5 days a week, as opposed to a therapy sessions once a week or once every second week. As the last day of the 4th week of therapy was used for the GMFM test, the children could receive a maximum of 19 physiotherapy sessions each period. The children were treated by an experienced pediatric physiotherapist (first author, T.U.). The intervention given was eclectic, influenced by current principles of the Bobath approach as it has evolved37,38 and by motor learning principles.39–41 The intervention aimed to meet each child’s level of development and clinical needs. Goals were set in collaboration with the parents. No standardized measures were used for this purpose. For each child, a total number of 3 to 8 goals was set, covering the functional areas of locomotion, sitting, and bilateral hand function.
The treatment highlighted practice of functional, meaningful tasks, in contexts appropriate for each child. Guiding the parents in their handling skills was integrated into the intervention. Parents were shown how to handle their children when dressing and undressing, and how to facilitate variation of movement patterns during play. Facilitation techniques were used when necessary, to initiate movements or to maintain positions, and the parents were instructed how to withdraw facilitation gradually. Activities included in each session were body alignment and weight transfer in various positions, increased and varied use of the more affected body parts, bimanual activities, and facilitation of sequences of movements. If the child was engaged and motivated for play, the therapist aimed for more repetitions and variations of the same activity rather than changing to a new activity. Age appropriate toys were available and benches in proper height for standing were used.
Each session varied from 40 to 60 minutes according to the child’s endurance. One of the parents always attended the session. An example of a typical therapy session for 1 child with unilateral CP is presented in Appendix 1. Since none of the children were yet walking, the therapy session presented could be representative for the 4 children with unilateral CP. There were the same elements of treatment for the child with bilateral CP as mentioned above, but since he was more severely affected, facilitation of sequences of movements up against gravity was more difficult. Instead, more time was spent on facilitating trunk stability and alignment in different positions of sitting and standing.
The data program Gross Motor Ability Estimator32 was used to calculate the GMFM-66 score. GMFM-66 scores for the individual children are presented graphically. To strengthen the analysis of the GMFM-66, the 2 SD band analysis technique was used.30 The mean and 2 SD of the baseline data were calculated. The 2 SD band around the baseline data was plotted across both the baseline and intervention phases. If 2 subsequent points fell outside the 2 SD band, we concluded that a significant difference existed between baseline and intervention phases.30
The GMFM-88 scores of all children were visually inspected with help of celeration lines. To construct a celeration line, 8 to10 data points are recommended.29,42 Even though we had only 2 to 5 data points in the baseline phases, we chose to construct a celeration line to support the visual inspections. With only 1 and 2 data points in the periods B and A, respectively, we concluded that constructing trend lines for these periods were inadequate.
Compliance was high for all children (Table 2). In period B1 the mean attendance was 93%, and in period B2 it was 92%. The registered absences during these 2 periods were either due to bad weather conditions or the treating physiotherapist being absent. One child had to stay at home for a couple of days because of high fever.
The individual results of the GMFM-66, with the 2 SD band are presented in the upper panels of Figures 2 to 6, and the scores from the GMFM-88 are presented in the lower panels.
Measured by the GMFM-66, Child 1 did not show a significant difference in function from the baseline phase until the second period of intensive therapy (B2) when the scores exceeded the 2 SD band (Fig. 2). According to the GMFM-88 results, his gross motor development was continuous during different periods and all of the data points were slightly above the celeration line.
This child had consistent improvement of her GMFM-66 scores, especially in the baseline period, giving a broad 2 SD band (Fig. 3). The difference in motor function from baseline did not exceed the 2 SD band until period B2. The data points of the GMFM-88 scores with a celeration line, confirmed the continuous improvement in gross motor items, as almost all the data points were along the same line.
Compared with the other 4 children, Child 3 had a different profile in his GMFM-66 scores (Fig. 4). He had no change in scores during the baseline period, making the mean baseline identical to the ±2 SD. During the first intervention period, his GMFM-66 scores increased, showing a small but significant difference in motor function from the baseline period. We saw the same increase in scores during period B2 and there were small changes in scores during periods A2 and A3. Inspecting the GMFM-88 scores did not confirm this, as almost all the data points were along the celeration line.
The GMFM-66 scores of Child 4 showed similar profiles to the scores of Child 1, with little increase during the first intervention period (Fig. 5). During periods A2, B2, and A3 the scores were above the 2 SD band, indicating a significant difference in motor function from the baseline period. The slope of the graphed GMFM-88 scores changed and got steeper during periods A2 and B2 with the data points above the celeration line, indicating acceleration in gross motor development compared with baseline.
Child 5 had similar profiles to Child 2 in his GMFM-66 scores (Fig. 6). He had an unstable baseline and a broad 2 SD band. This child missed the GMFM test before period B2 due to fever, and interpretation of results is more difficult. When inspecting the graphed GMFM scores, there seemed to be a significant increase in scores relative to the baseline period during B2, but since one data point was missing we could not tell whether this increase came during period B2 or A2. The graphed GMFM-88 scores show increase in scores above the celeration line during the last period indicating acceleration in gross motor development compared with baseline.
All children had significant differences in scores from the baseline period, but the increases in scores came during both periods A and B. Overall, the children with unilateral CP showed a more similar and continuous development throughout the study period, compared with Child 3, with bilateral CP and GMFCS Level 4 severity.
The GMFM-88 change scores (%) for all children, from one test to the next, are presented in Table 3. Comparing all children’s change scores, there was a tendency for the last treatment period (B2) to demonstrate higher change scores than B1.
In this study, our aim was to examine whether periods of physiotherapy provided 5 times per week for 4 weeks, compared with standard care, would accelerate motor function in 5 infants with CP. Several previous studies have concluded that, due to the heterogeneity of children with CP, single-subject designs are suitable in studying such groups.20,21,43 Our study was strengthened by using a multiple-baseline, across subjects design and by implementing 2 periods of intensive physiotherapy. The children were preliminarily classified according to the GMFCS even though the reliability of classifying children aged <2 years has not yet been demonstrated satisfactorily.44
In general, in inspecting the GMFM-66 scores for all children, the effect of intensive physiotherapy compared with physiotherapy as usual was inconclusive. Only Child 3, who had bilateral CP showed significant increase in GMFM-66 scores during both periods B1 and B2. Compared with periods when he received therapy as usual, periods of intensive physiotherapy seemed to give an acceleration of motor function. But this was not confirmed by his GMFM-88 scores.
The children with unilateral CP had increase in motor function during both periods B and A. Retention of motor function in periods A2 and A3 were expected. The improvement in motor function during these periods could be explained by the fact that intervention in period B1 had given them acceleration in motor development, which continued as they were using their new skills. The parents having changed their handling and stimulation of their children could also been an explanation. Child 2 and 5 had no physiotherapy sessions in the A periods, and Child 1 only received physiotherapy in period A3. Child 4 and 5 showed increases in motor function, especially exceeding their natural maturation after physiotherapy interventions were implemented, as measured by GMFM-88. The percentage change scores for Child 1, 2, 4, and 5 during a 24-week period were high compared with the findings of Kolobe et al45 (Table 4).
The GMFM change scores of the 4 children with unilateral CP were higher during period B2 than during B1, except from Child 1 (Table 3). The greater increase in motor functions during period B2 compared with B1, might be due to more optimal ages for intervention in the latter period, conforming to periods during which children normally would gain many new skills. Also, the therapist-child relationship could play an important role: Child 2 was very hesitant to work with the therapist during the first period B, and had no motor progress according to the GMFM-66 and the GMFM-88 during this period. During period B2, she was more interactive and easier to engage in play.
The reason for increased scores during period B2 could also be found in the measurement tools. The GMFM test could be more sensitive at measuring motor progress for slightly older infants. The GMFM test is the best standardized tool available to measure gross motor functions in children with CP, but we question whether this test is adequate in measuring motor progress in children just 6 months old. According to the GMFM-66 a minimum of 13 items, including items with some success and items that the child cannot complete, is required to estimate the true ability of a child.32 Most of the items were initially too advanced for the children in this study, and some of them were scored on only a few items (4 infants were scored on 7 or 8 items only). All children were given a score of zero, on 10 of the not tested items. By also using the GMFM-88, we collected more information about each child.
According to Kolobe et al,45 when using the GMFM as an outcome measure, the intervals between tests should be at least 3 months. Frequent use of the GMFM is not ideal for measuring motor function in very young children. In our study the intervals were only 4 weeks, and the probability of seeing changes was therefore diminished. By defining our experimental phase from week 16 to 40, covering both periods with and without intervention as in the study of Trahan and Malouin,25 Child 4 and 5 had a marked acceleration in gross motor function compared with the baseline periods (Figs. 5 and 6). The GMFM-66 and the GMFM-88 results for a 24-week period starting at week 16 are presented in Table 4. With this 24-week interval the 95% confidence intervals did not overlap, giving a significant change of motor function in all 5 children, as measured by the GMFM-66, during this period. Progress in gross motor skills is expected in young children,4 but the increases in GMFM-88 scores for our 5 children were quite notable. The mean increase in GMFM-88 percentage scores, during the 24-week period, was 19% (Table 4). This change score exceeded a mean change score of 4.2% during an equivalent period for 24 children with CP, mean corrected age 13.9 months, found by Kolobe et al.45 A limitation of our study is that the tester had access to one set of previous scores. This fact could bias our results.
An alternative to the use of GMFM could have been measuring quality of movement, by the use of, for example, the Gross Motor Performance Measure.46,47 It would also have been preferable to assess the children’s bimanual activity by the use of another test than the GMFM. One outcome measure designed to evaluate movement patterns and hand function in children with CP is The Quality of Upper Extremity Skills Test.48 The Quality of Upper Extremity Skills Test is validated for use in children with CP, age 18 months to 8 years. At the time of inclusion the infants in our study were much younger and the use of this test was not contemplated.
In our study, the child with bilateral CP was the child who showed the most obvious progress after periods of intervention measured by the GMFM-66. Two of the children with unilateral CP obviously improved after intervention started, compared with the celeration line for the baseline periods. But it was not possible to distinguish effects of intensive physiotherapy from the effects of physiotherapy as usual.
Less than half of the individual goals were achieved during the 2 intervention periods. Goal attainment might have been different if we had used a standardized measure, for example, Goal Attainment Scaling.49 However, many parents found taking part in the goal setting difficult. Some of them had not come to terms with the diagnoses of the child yet, and they did not know what motor progress to expect. Their main concerns could rather be whether their child would be able to walk or could have other problems, such as cognitive impairments. Shortly after period B2, semistructured interviews with each set of parents were performed. Focuses of the interviews were the children’s function and the parents’ experiences and satisfaction with periods with and without daily physiotherapy. The results of these interviews will be presented in a separate article.
Because of the high attendance percentage, the 4 weeks of daily physiotherapy seemed to be acceptable to the parents. Most parents reported that they were pleased having participated in the study, but organizing daily routines during periods with intensive physiotherapy had been a challenge. They also reported that seeing a therapist frequently had given them the opportunity to really learn the handling skills. This had made the transfer into daily activities easier, particularly important during period B1, when they were new to the children’s diagnoses. The parents appreciated pauses (A2 and A3) in the intensive therapy, but some felt that these periods had been too long. Only 1 pair of parents reported that in the future they would prefer regular appointments once every second week.
We had defined intensive physiotherapy in terms of frequency. Intensive physiotherapy can also be understood in terms of amount and type of activity as in the study of Ulrich et al.50 Our study would have been strengthened if other aspects of intensity had been made explicit, as well as the contents of the intervention. No records were made comparing sessions in the children’s homes versus sessions at the hospital. It is a challenge to document the contents of intervention. Physiotherapy consists of a number of various components: the influence of the therapist and child interaction, the therapist’s expertise, the parent’s and child’s attitude toward therapy, and what the parents themselves are doing regarding handling and facilitation.20 Each of these elements of therapy needs to be addressed more fully to know what is bringing about motor progress. There is also a lack of a common vocabulary to describe similar treatment, further complicating these issues.51
Concerning the effect of periods of daily physiotherapy for the 5 infants participating in our study, our findings are inconclusive. All 5 infants showed motor progress compared with baseline, but there were no clear tendencies for gross motor function acceleration during periods with daily physiotherapy compared with periods with physiotherapy as usual. Given the small sample, the findings cannot be generalized to other children with CP. Whether the intensive therapy optimized motor functions, or the progresses in motor function were caused by other factors, need to be further investigated.
Infants in high risk of CP continue to be referred to physiotherapy at an early age. Blocks of intensive therapy can be good alternatives to regular dosage of physiotherapy for the youngest children with CP. Physiotherapy intervention, its intensity and frequency should be tailored to meet the need of each individual infant and their parents. More studies with larger numbers of children, studies with different age groups and different severity level of CP, need to be conducted to be able to give recommendations about how to best optimize gross motor function in children with CP. To get more knowledge about the effect of physiotherapy intervention for the youngest children, studies with infants under 6 months of age need to been conducted. For the youngest infants other standardized measurement tools, which might be more sensitive to change, can be used. From what we have learned in this preliminary study, future studies should also include more documentation of the contents of intervention and a log or record of the different sessions and of home activities.
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