Postural control during reaching in preterm children with cerebral palsy.

Postural control during reaching with the dominant arm was assessed in 58 preterm children with cerebral palsy (CP) aged 2 to 11 years, comprising 34 with spastic hemiplegia (17 males, 17 females) and 24 with bilateral spastic CP (bilateral CP; 15 male, 9 females). Assessments were made by multiple surface electromyogram (EMG) and kinematic recording. Mean gestational age at birth for the children with spastic hemiplegia and those with bilateral CP was 28.6 weeks (SEM 0.33) and 28.2 weeks (SEM 0.34) respectively; their mean birthweights were 1158 g (SEM 58) and 1190 g (SEM 59) respectively. All but one of the children with spastic hemiplegia could walk without restriction, the exception being a child who had self-mobility with limitations. In the group of children with bilateral CP, nine walked without assistive devices, 10 could walk with assistive devices, and five children needed a wheelchair for self-mobility. Comparison data of 29 typically developing children (10 males, 19 females) born at term with appropriate birthweight were available. Results indicated that in most children with CP the basic level of postural control ('direction-specificity', i.e. muscle activation on the side opposite to direction of body sway) was intact. However, the children with CP showed dysfunctions in: (1) recruitment order of the postural muscles, i.e. they exhibited a stereotyped top-down recruitment; and (2) the ability to modulate muscle contraction (that registers on EMG) to task-specific conditions. The latter dysfunction was more pronounced in children with bilateral CP than in those with spastic hemiplegia. Postural dysfunctions were correlated to some extent with the degree of disability in everyday activities as assessed by the Pediatric Evaluation of Disability Inventory.