COURSE AND PROGNOSIS
OUTCOME MEASURES
Children with CP often change over time, due either to growth and development or as a result of treatment.
Various means of determining change may be employed. Subjective evaluations that ask the child, parent, or therapist his or her opinion are most commonly used. Occasionally, more quantified techniques are employed, particularly in research settings, although clinical use also occurs.
Outcome measures may best be classified by the domains they seek to measure and the methods of assessment. Using the International Classification of Functioning, Disability and Health—Children and Youth Version (ICF-CY) (257), measures can be divided into those that define body structures, body function, activity and participation, and domains outside the ICF (Table 14.3), and this rubric is the focus of efforts to develop a core set of outcomes for CP (258). Few measures are pure assessments of only one domain; rather, it is common to see items spread across multiple ICF domains (259).
Body Structure and Function
When considering children with CP, few outcome measures directly relate to body structure. Imaging such as functional MRI or physiologic measures like transcranial magnetic stimulation or electromyography could be considered in this domain. Because very few interventions for CP are expected to alter body structures, such as brain tissue, these types of outcome measures are seldom employed. Many outcome measures for CP address body function. Body function is assessed with spasticity/movement disorder measurement (Ashworth, Modified Ash-worth, and Tardieu scales, the Hypertonia Assessment Tool, or specialized measurement systems), strength measurement (muscle grading or dynamometry), or ROM.
Activity and Participation
Because many interventions for CP are intended to reduce activity limitation or promote participation, a wide range of outcome measures are specific for these ICF domains. Common assessments of gross motor function and walking include the GMFM and Gross Motor Performance Measure as well as gait analysis, ranging from observational scales (Physician Rating Scale) to instrumented digital kinematic analysis. Fine motor ability may be assessed with the Quality of Upper Extremity Skills Test, Assisting Hand Assessment, and Melbourne Assessment of Unilateral Upper Limb Function, among others. More global functional measures include the Functional Independence Measure for Children (WeeFIM), the Pediatric Evaluation of Disability Inventory, the Pediatric Outcomes Data Collection Instrument, and the Bruininks-Oseretsky Test of Motor Proficiency. Assessment of energy expenditure or efficiency, timed walking tests, and movement monitors are also used to assess the domain of activity in children with CP.
The Pediatric Evaluation of Disability Inventory (standard and computer-adapted test versions) and the Canadian Occupational Performance Measure assess both activity and participation realms. Participation for children with CP is most often assessed with the Children's Assessment of Participation and Enjoyment and the Preferences for Activities for Children. The Activities Scale for Kids and Assessment of Life Habits for Children are also employed in this domain. Some instruments address health status or QOL, and may be placed in the domain of participation, while other instruments assess environmental factors. Common outcome measures in this group include the CHQ, KIDSCREEN, or other generic pediatric measures, the Cerebral Palsy Quality of Life—Children, and Goal Attainment Scaling.
Developmental assessments are generally wide in scope and used more frequently in younger children. These include the Peabody Developmental Motor Scales, Battelle Developmental Inventory, Vineland Adapted Behavior Scales, Denver II, Bayley Scales of Infant Development, and Revised Gesell Developmental Schedule.
Three key arenas of assessment are discussed in the following.
Gross Motor Function Measure (GMFM)
The GMFM is a functional outcome tool that was developed specifically for use in CP (279). Widely used in research settings, the GMFM is also employed clinically for the evaluation of children with CP. The GMFM consists of a broad range of gross motor tasks, in which a trained evaluator observes a child attempting to complete over a 45- to 60-minute time interval. The item set and basal and ceiling approaches for the GMFM permit more rapid administration (296). Five dimensions of function (lying and rolling; sitting; crawling and kneeling; standing; and walking, running, and jumping) are examined. Specific scoring algorithms result in a score that can be used as an interval measure.
Gait Analysis
Instrumented gait analysis is another objective functional measure that is widely used in CP (283). Many centers do not use gait analysis; other centers rely upon it heavily, particularly in guiding treatment decisions such as orthopedic surgery. This technique can only be employed for children who have some ability to walk, even if they require gait aids. Gait analysis involves having a child walk in a specialized laboratory wearing markers and muscle activity sensors. Using sophisticated computers, cameras, and force plates implanted on the floor surface, the child's movement patterns can be analyzed in great detail. Information about movement patterns in all planes, kinetics, and kinematics is generated. Although some controversy exists as to the reproducibility of gait analysis results and the means by which gait analysis should be employed to guide surgical decision making (297), gait analysis remains a common tool for the evaluation of CP.
TABLE 14.3 OUTCOME MEASURES USED IN CP
