How does early physical therapy intervention affect gross motor development in children with cerebral palsy?

According to the World Health Organization, infants' development consists of attaining the following six gross motor milestones: sitting without support, crawling on hands and knees, standing with assistance, walking with assistance, standing alone, and walking alone. These milestones need not be achieved in an exact order at an exact age, and sometimes milestones are skipped throughout a child's development. This makes diagnosis of gross motor development delay difficult and variable, and is often diagnosed by norm-referenced/criterion-reference tests. These delays are typically thought to be due to a change in the normal development and function of a child's central nervous system; cerebral palsy is a disorder that interferes with this typical devlopment14.Cerebral palsy is a group of movement disorders that is caused by injury to the brain occurring before or during a child's birth or during the first three to five years of a child's life. There is wide variability in the severity of functional limitation, types of movement disorder, and the body parts affected in individuals with cerebral palsy.

Classification
Description
Severity

Mild
Can move without assistance. Does not limit daily activities.
Moderate
Requires braces, medications, and adaptive technology to accomplish daily activities.
Severe
Requires a wheelchair. Significant difficulty in accomplishing daily activities.
Type

Spastic
Increased muscle tone
*Most common – effects about 80% of people with CP
Dyskinetic
Problems controlling movement of their extremities
*Includes athetoid, choreoathetoid, and dystonic cerebral palsy
Ataxic
Problems with balance and coordination
Mixed
Have symptoms of more than one type of CP
*Spastic-dyskinetic CP is most common
Body Parts

Hemiplegia
Involvement of one arm and one leg on the same side of the body
Diplegia
Greater involvement of arms than legs
Quadriplegia
Equal involvement of all extremities

Gross Motor Function Classification System (GMFCS)

The GMFCS is a five level system that describes gross motor function in children with cerebral palsy. The levels are divided into four age groups to describe gross motor ability in children up to 12 years of age. The age groups are as follows: under 2 years, 2 to 4 years, 6-8 years, and 8-12 years. In general, a child's GMFCS level will not improve after the age of 5 years.

Table 1: General Headings for GMFCS Levels

Level I
Walks without limitations
Level II
Walks with limitations
Level III
Walks using a hand-held mobility device
Level IV
Self-mobility with limitation; may use powered mobility
Level V
Transported in a manual wheelchair

Gross Motor Function Classification System

Common Physical Therapy Intervention
Goals

  • Foster independence by improving functional mobility
  • Strengthen and encourage growth of muscles
  • Improve ability to move all parts of the body
  • Coordination, balance
  • Prevent joints form becoming tight and prevent contracture

Common Interventions include soft tissue mobilization, joint mobilization, stretching, therapeutic exercise and endurance exercises designed to meet therapy goals. Can involve braces/splints to straighten and support the child’s joints and help manage uncontrolled limb movement.
Early childhood (0-4): focus on positioning, movement, feeding, play, and self-calming. Through play young children can learn many skills that will improve strength, movement, and function.
Age 5-12: At this age children are going through growth spurts, which require frequent adjusting to PT treatment. Priorities are walking, transfers, personal hygiene, play, socialization, and adaptive equipment to meet social and physical changes. Focus on prevention of posture problems and joint limitations by encouraging mobility, managing muscle/joint pain, and bracing to maintain function. Lifelong habits are formed at this age, so the interventions provided now can improve health and function for the rest of his/her life11.



Research in Physical Therapy Interventions for Children with CP

Research has focused on interventions to reduce gross motor development delay in children with CP through physical therapy9. Generally individuals received greater amounts of therapy at younger ages, but there is a spike in services for individuals older than 18 years for GMFCS levels 2 and 3. Caution should be taken, however, with this finding as there are relatively few people who fall into this category. There is a decrease in service for age 12-18 years, except for children in level 5 who received slight more therapy2.
Task Specific Training


Children demonstrate neural plasticity throughout their development, and it is thought that to optimized neural plasticity, task-specific training is necessary; if motor development is to be achieved, motor activity must be the focus of the intervention7,916,17. In a study on skill acquisition, seven children with severe learning difficulties and quadriplegic CP were given an intensive therapy program with a goal of improving a specific functional activity. During the program, the children showed significant progress towards the specified goal, but less improvement in other functional areas. Skills acquired during this program were shown to be maintained an in some children even improved after the intensive program was reduced to a normal, less frequent therapy program. Therefore, the results of this study seem to show the importance of clear and measureable goals in the success of a treatment program for children with CP to improve compliance and outcome4.

Ambulation

Ambulation is one of the most debilitating impairments for children with CP. These children are hindered by decreased walking speed and endurance, decreased step and stride length, and decreased toe clearance14. The cerebrospinal tract in humans matures after birth. Yang et al. estimated the critical period for maturation to be within the first two years of life. Prior to this study, most gait training for children with cerebral palsy was performed after age two. However, this study began gait training with five subjects who were less than two years of age and found that these children showed greater improvements in walking and gross motor function than those who began gait training after two years. Therefore, this study suggests early gait training interventions could led to higher functional outcomes in children with CP19.

A systematic review of treadmill training in children with CP revealed that treadmill training can improve walking speed but not walking endurance. Additionally, it was found that treadmill training can improve general gross motor function, and the greatest benefits may be seen in children who have more severe impairments17. Authors studied the effects of a 12 week intervention consisting of treadmill walking without body support for no more than 30 minutes/session. Significant differences were revealed between this intervention and a control group. Gross motor function and self-selected walking speed means were higher with treadmill training. This intervention had no effect on lower extremity spasticity7. A quasi-randomized control trial investigated the effects of home-based treadmill training on gross motor function in young children with CP. Children in the experimental group walked on a portable treadmill twice a day, six days a week for six weeks. The results of this study indicate that an intensive treadmill program for children from 9-36 months can accelerate the onset of walking with and without an assistive device, improve speed, and overall mobility. Two of the children in the experimental group were able to exceed the typical walking speed of children this age. This shows that an early, intensive locomotor treadmill training program can enable young children with CP to keep up with their age-matched peers10. In a separate study, school age children with CP participated in a RCT to determine whether or not partial body weight supported treadmill training over a period of 6 weeks could increase self-selected walking speed and walking endurance. Children who participated in 6 weeks of PBWSTT significantly increased their walking speed compared to their control counterparts, but no significant difference was found in walking endurance between the two groups9.

The use of an electromechanical gait trainer was studied in 18 subjects over 2 weeks to test the effect of improving walking in children with CP. The gait trainer included a harness that supported partial body weight and foot plates that simulated stance and swing phase. Throughout the intervention, body weight support was decreased and walking speed was increased. Analysis showed that at post treatment and at one month follow up there was a significant increase in gait velocity and endurance. Additionally, the intervention group showed significant improvements in lower extremity gait kinematics14. However, results on the lasting effects of early intervention are mixed. School aged children with bilateral cerebral palsy participated in a RCT to determine the effect of a 6 week exercise intervention, static bike or treadmill, on gross motor function for non-ambulant children with CP. Both interventions significantly improved standing ability, walking speed, and walking duration compared to the controlled groups. These effects on gross motor function were rapidly reduced after cessation of the intervention as measured in the follow-up assessments5. Additionally, Bower, et al. observed improvements in gross motor function in children ages 3-12 at levels III or below on the Gross Motor Function Classification System. This study found that increasing the intensity of the physical therapy program for six months yields no greater improvement in motor function than a standard therapy routine. Any additional functional gains made during this time of intensified therapy were lost over the following six months if a regular treatment schedule was resumed3.

Intermittent Intensive Physical Therapy
A pilot study on intermittent intensive physical therapy was conducted with a two-fold purpose: to determine the feasibility of an intensive treatment program for children with CP (4 sessions/week for 4 weeks separated by 8 week rest periods) and to measure changes in gross motor function after periods of intense treatment and after rest periods. Results showed that parent and child tolerance with the intensive program structure was high. Four week periods of increased therapy sessions improved the therapist/child relationship which also increased compliance and improved treatment outcomes. It was noted that intense program periods should not last longer than four weeks, however, or the child gets too tired to participate. During the eight weeks, all five children who participated in the study maintained the improvements they made in functional activity during the four weeks of increased therapy intensity. The eight week rest period also allowed the child and their family to go back to a more normal lifestyle. The results of this study show that alternating short periods of intensive therapy with longer rest periods seems to maximize improvement in motor function. A program that is intensive without being too tiring for the child seems to provide the greatest treatment benefits for children with cerebral palsy15.

Regardless of a child's future ability to walk, children spend a lot of time sitting. Without the ability to sit independently, children with CP are considered to be at a low functional level. Therefore, the acquisition of independent sitting is an important functional goal. A randomized control trial was conducted on 10 children with CP (ages 1-2) to compare the effects of an intensive intermittent physical therapy program versus a standard program on the acquisition of independent sitting. Following four weeks of baseline interventions, five of the infants underwent the intensive eight week program while the other five infants served as the control group and were administered a regularly scheduled weekly program. The results of this study show that a goal-directed (in this case with a focus on sitting) intensive physical therapy program has the potential to be beneficial for infants, but those children with higher functional levels will not benefit as much as those with low functional levels13.


Motor Milestones and Predicting Ambulation

A retrospective study to determine predictors of ambulation in children with CP who were not yet walking at age two found that motor milestones were strong predictors of ambulation by age seven. The three levels of ambulation defined in this study were walks with support of assistive device, walks unsteadily alone at least 10 feet, and walks well alone at least 20 feet. The motor milestones investigated in this study were rolling, sitting, and pulling to stand. As expected, children who were not rolling by age 2 had the lowest ambulation rate and highest mortality rate at age 7. Children who were rolling, sitting, and pulling to a stand at age 2 has the highest likelihood of full ambulation. Other factors that were found to be significant predictors of ambulation were the type of cerebral palsy and blindness. Figure 1 shows the likelihood of ambulation at ages 1-15 for children who were nonambulatory at age 2. The likelihood of walking with or without support by age 7 was as high as 75% in children who were rolling, sitting, and pulling to a stand at age 218.

ambulation charts.gif
Figure 1: Likelihood of Ambulation Based on Motor Milestones at Age 2


Gross Motor Function Classification System and Predicting Gross Motor Development

The GMFCS was developed to objectively classify current gross motor function in children with cerebral palsy. Since the development of this system research has been done to determine whether a child's GMFCS level can be utilized to predict ambulation from ages 6-12. One study found that the positive predictive value of GMFCS levels I and II at 1-2 years in predicting ambulation by 12 years was 0.74. The negative predictive value of GMFCS levels IV and V at 1-2 year in predicting ambulation by 12 years was 0.9020.

A prospective, longitudinal study used the GMFCS to predict gross motor development in children with cerebral palsy. A sample of 657 children from age 1-7 years who were receiving medical, orthopedic, and developmental therapy services participated in the study. This study used Gross Motor Function Measure (GMFM-66) to assess gross motor function. The results of the study predicted GMFM-66 limits for each level of the GMFCS and also evaluated how quickly children progressed towards these limits. Study findings indicate that children within the higher classifications in the GMFCS approach their motor function limit much quicker than children in the lower levels. Figure 2 below shows when children of each level are expected to reach 90% of their potential. For example, children at level III are expected to reach 90% of their potential by age 3-7. The GMFCS can be used to give parents an idea of their child’s potential gross motor function and will also aid healthcare professionals in setting goals and guiding interventions12.


motor development curves.gif
Figure 2: Motor Development Curves Based on GMFCS Level

GMFM-66


Research on physical therapy intervention for children with CP is still in its early stages, and evidence on the long term gains is not strongly supported. A retrospective study of children with CP receiving conventional physical therapy revealed that gross motor function improved differently depending on GMFCS with level 2 progressing the fastest. The results also show that physical therapy was most effective for younger children and the older children had continuing progression with gross motor function up to eight years of age6. Previous research that documents declines in gross motor function found that 13 out of 29 people with CP who could walk independently in childhood lost the capability between ages 20-40 years. Additionally, children who walked unsteadily and sometimes used a wheelchair were the most likely to lose ambulatory ability as young adults. Children in levels 3, 4, and 5 are at risk of losing motor function, while there is no evidence of functional decline for children in levels 1 and 2. Children classified in levels 3, 4, and 5 peaked with their gross motor function and then declined at 7 years 11 months, 6 years 11 months, and 6 years 11 months, respectively, continuing into young adulthood, which reached clinical significance.
This leads to the conclusion that the probability of decrease in mobility depends on the initial degree of mobility limitation1. Other research lends support to this idea. Day et al. found that children are likely to maintain ambulatory ability during their next 15 years. Those who walked and climbed stairs without difficulty at age 10 had only a 23% chance of functional decline 15 years later. Those who ambulated with some difficulty but did not use a wheelchair had a 33% chance of improving their walking ability, defined as being able to walk unsteadily alone at least 3 m, and only an 11% chance of becoming non-ambulatory. Those who used a wheelchair were 34% more likely to lose ambulatory ability, and improvement in ambulation after age 25 was unlikely in all cases of ambulatory ability and decline was likely8.



Summary

  • Early physical therapy intervention in children with CP is important to promote mobility and prevent secondary impairments such as tone abnormalities and contractures.
  • Gait training prior in children prior to age 2 resulted in improved gross motor outcomes.
  • Rolling, sitting, and pulling to a stand are significant predictors of ambulation later in life.
  • GMFCS levels are useful for goal setting and intervention selection.
  • Children at GMFCS level II demonstrated faster progression of skills.
  • Younger children responded better physical therapy.
  • Children in GMFCS levels I and II are less likely to lose the ability to ambulate later in life.





References

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2. Bailes AF & Succop P. Factors Associated With Physical Therapy Services Received for Individuals With Cerebral Palsy in an Outpatient Pediatric Medical Setting. Physical Therapy 2012; 92(11):1411-1418.

3. Bower E, Michell D, Burnett M, Campbell MJ, & McLellan DL. Randomized controlled trial of physiotherapy in 56 children with cerebral palsy followed for 18 months. Developmental Medicine and Child Neurology 2001; 01:4-15.

4. Bower E & McLellan DL. Effect of increased exposure to physiotherapy on skill acquisition in children with cerebral palsy. Developmental Medicine & Child Neurology 1992; 34:25–39.

5. Bryant E, Pountney T, Williams H, & Edelman N. Can a six-week exercise intervention improve gross motor function for non-ambulant children with cerebral palsy? A pilot randomized controlled trial. Clinical Rehabilitation 2013 27(2):150-9.

6. Chen, YN, Liao SF, Su LF, Huang HY, Lin CC, & Wei TS. The effect of long-term conventional physical therapy and independent predictive factors analysis in children with cerebral palsy. Developmental Neurorehabilitation 2013; 16(5):357-362.

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8. Day SM, Reynolds RJ, Shavelle RM, Strauss DJ, & Wu YW. Change in ambulatory ability of adolescents and young adults with cerebral palsy. Developmental Medicine & Child Neurology, 2007; 49(9):647-653.

9. Dodd KJ & Foley S. Partial body-weight-supported treadmill training can improve walking in children with cerebral palsy: a clinical controlled trial. Developmental Medicine & Child Neurology 2007;49:101-105.

10. Mattern-Baxter K, Mcneil S, & Mansoor JK. Effects of Home-Based Locomotor Treadmill Training on Gross Motor Function in Young Children With Cerebral Palsy: A Quasi-Randomized Controlled Trial. Archives of Physical Medicine and Rehabilitation 2013; 94(11):2061-067.

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