Bimanual coordination and motor learning in children with unilateral motor disorders

Introduction\nAppropriate bimanual coordination is essential for many tasks in daily life. Children with unilateral cerebral palsy (uCP) however struggle with the execution of such tasks. Extensive research has been done investigating motor impairments on a functional level using standardized procedures. There is a lack of studies however looking at the specific problem of coordination of a bimanual task, especially with respect to the different underlying neuropathologies. \nAims & Methods\nWithin this thesis, kinematics of bimanual hand movement during a role differentiated bimanual box opening task in children with uCP, as well as in typically developing children (TDC) of similar ages, were investigated. The aims were: i) to identify behavioural changes in peak periods of development of the corpus callosum and areas of the prefrontal cortex, both of which are related to bimanual function in typically developing children; ii) to explore the relation between motor impairments of children with uCP and their bimanual coordination and iii) to investigate the impact of various underlying neuropathologies on bimanual coordination in children with uCP. \nResults\nFor the first study, a total of 37 TDC between 5 and 16 years were included and allocated to their respective age-group: Young Children (YC: 5-6 years), Old Children (OC: 7-9 years) and Adolescents (AD: 10-16 years). The two older groups performed the task significantly faster than YC. Likewise, a trend (yet without reaching significance) towards a more ideal temporal sequencing was shown between YC and the two older groups. In contrast, spatial accuracy as expressed by the path length increased only in the AD group. \nFor the second study, a total of 37 children with uCP between 7 and 17 years were included. Children presented manual impairments between levels I and III (according to the Manual Ability Classification System). It could be shown that task duration increased and spatial accuracy decreased with increasing levels of impairment, especially in children with higher levels of impairment (level III). Furthermore it could be shown that a subgroup of children experienced an involuntary interference when moving their affected hand, limiting the use of their less affected hand.\nThe third study utilised a multiple case study involving nine children diagnosed with uCP with neuroimaging and neurophysiological data. The children were found to have various neuropathological patterns resulting in different forms and severities of motor impairments. It could be shown that grey-matter lesions had the most severe impact on manual abilities. \nConclusion\nIn TDC, performance of bimanual hand movements was temporally related to peak developmental periods of the corpus callosum, emphasizing the importance of interhemispheric exchange of information for bimanual coordination. In children with uCP, bimanual performance was related to the level of impairment of the affected hand. In addition it was found however that some children show excessive bimanual interference when using their affected hand in a bimanual task which limits the functionality of the less affected hand, possibly related to i) ipsilateral corticomotor projection patterns from the less affected hemisphere to the affected hand or ii) lack of suppression of interhemispheric crosstalk. It could also be shown that the various neuropathologies can affect bimanual motor control differently. Detailed diagnosis of the neuropathology and motor impairment are thus essential for the planning of tailored therapy interventions.\n