Development of A Classification of Children with Developmental Coordination Disorders Based on Clinical Subgroups
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Background. Developmental coordination disorder (DCD) is a neurological disorder that is typically diagnosed in school-age children and effects approximately 5-10% of school-age children in US. Children with DCD often demonstrate a variety of motor concerns, including poor motor, sensory and postural control function compared to typical peers. They may show delayed and poor quality of fine motor or gross skills, especially higher-level motor skills, and experience challenges in their daily life activities. The presumed central nervous system (CNS) pathology of DCD has not been confirmed. Also, because these symptoms are relatively subtle, diagnosis and recommendations for intervention are difficult but critical. Better evaluation and classification of children’s motor concerns is warranted. Objectives. To systematically determine the knowledge base of brain pathology in DCD, to examine new potential tests to determine children’s ability within certain important and specific constructs that are problematic for children with DCD, and to explore defining subgroups within children who have a DCD diagnosis. Methods. A systematic review was conducted to determine the knowledge base for the pathology in DCD by reviewing eight brain-imaging studies. Nineteen pairs of children with DCD and age-matched peers with typical development (TD) were tested to validate an assessment of motor planning, the Motor Planning Maze Assessment (Maze) and an assessment of gait coordination, three items from the Functional Gait Assessment that were modified for children (pediatric modified FGA, pmFGA). Paired-t tests and cross tables were used for statistical analysis. Children with DCD were also examined using tests across domains of fine motor, gross motor, balance, coordination, sensory processing, and intelligence. Through visual analysis using pattern recognition of test results portrayed by standardized percentile ranks, subgroups are proposed. Results. The systematic review revealed that pathologies of DCD related to motor function include many areas of the brain and several tracts in children with DCD. The validity of the clinical tests of motor planning and gait coordination were supported as assessments that differentiate motor function in a group of children with DCD and their peers with TD. Finally, via detailed examination of the children with DCD, it appears that clinical characteristics among several domains identified by standardized clinical assessments do suggest that subgroups of DCD exist. Limitations. Few studies exist examining the pathology of DCD. One psychometric parameter, construct validity, of the MAZE and pmFGA was examined. The sample size for sub-group analysis was small; therefore more robust statistical analyses could not be employed. Measurements used addressed some of the problematic domains in children with DCD, but other tests/measures are likely necessary. Conclusions. Preliminary data exists to define the pathology of DCD. The MAZE and pm FGA are two promising measures that could be used within the evaluation of children with DCD. Analysis of a group of standardized clinical assessments suggests that subgroups of DCD are identifiable. More reliable and valid statistical analysis with larger samples of children are needed in order to confirm the pathology, appropriate clinical measurements and identification of subgroups, which should better direct evaluation and intervention for children with DCD. Further research is warranted in all these areas.