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To evaluate the effect of 15° forward (FW) seat inclination and foot-support in children with cerebral palsy (CP) on postural adjustments during reaching. Observational study repeated-measures design; step two of two-step-project. Laboratory unit within University Hospital and two special education schools. 19 children (ten unilateral spastic CP (US-CP); nine bilateral spastic CP (BS-CP); Gross Motor Function Classification System levels I-III; 6–12 years old). Participants were able to take part for one one-hour session. Reaching while sitting in four seating conditions (FW or horizontal seat; with or without foot-support) applied in randomized order. Simultaneously, surface electromyography (EMG) of neck, trunk and arm muscles and kinematics of head and reaching arm (step one of two-step-project) were recorded. Primary outcome parameters were the ability to modulate EMG-amplitudes at baseline and during reaching (phasic muscle activity). Other EMG-parameters were direction-specificity (1st control level), and 2nd level of control parameters: recruitment order, and anticipatory postural activity. Motor behaviour measures: ability to modulate EMG-amplitudes to kinematic characteristics of reaching and head stability. Only foot-support was associated with increased tonic background EMG-amplitudes and decreased phasic EMG-amplitudes of the trunk extensors in children with US-CP and BS-CP (mixed-models analyses; p-values <0.01). The foot-support effect was also associated with better kinematics of reaching (Spearman's Rho; p-values <0.01). In terms of postural adjustments during forward reaching, foot-support enhanced the children's capacity to modulate trunk extensor activity, which was associated with improved reaching quality. FW-tilting did not affect postural muscle activity. • FW seat inclination does not affect postural EMG of reaching children with CP. • Foot-support in seated children with CP increases tonic trunk extensor activity regardless of CP type or seat inclination. • Increased tonic trunk extensor activity was associated with improved kinematics of reaching. [ABSTRACT FROM AUTHOR]

Background: Development of postural problems in Cerebral Palsy (CP) is largely unknown. Postural muscle activity is organized into two levels: 1) direction-specificity; 2) fine-tuning of direction-specific activity.Aim: To study development of postural control until 21 months corrected age in subgroups of infants at very high-risk (VHR) of CP: a) with and without CP at 21 months; b) with and without cystic periventricular leukomalacia (cPVL), the brain lesion with highest risk of CP.Methods and Procedures: Longitudinal electromyography recordings of postural muscles during reaching were made in 38 VHR-infants (severe brain lesion or clear neurological signs) between 4.7 and 22.6 months (18 CP, of which 8 with cPVL). Developmental trajectories were calculated using linear mixed effect models.Outcomes and Results: VHR-infants with and without CP showed virtually similar postural development throughout infancy. The subgroup of VHR-infants with cPVL improved performance in direction-specificity with increasing age, while they performed throughout infancy worse in fine-tuning of postural adjustments than infants without cPVL.Conclusions and Implications: VHR-infants with and without CP have a similar postural development that differs from published trajectories of typically developing infants. Infants with cPVL present from early age onwards dysfunctions in fine-tuning of postural adjustments; they focus on direction-specificity. [ABSTRACT FROM AUTHOR]

Background: The effect of forward-tilting of the seat surface and foot-support in children with spastic cerebral palsy (CP) is debated.Aim: To assess the effect of forward-tilting of the seat surface and foot-support in children with CP on kinematic head stability and reaching.Methods: Nineteen children functioning at Gross Motor Function Classification System levels I-III participated [range 6-12y; ten unilateral spastic CP (US-CP) and nine bilateral spastic CP (BS-CP)]. Kinematic data were recorded of head sway and reaching with the dominant arm in four sitting conditions: a horizontal and a 15° forward (FW) tilted seat surface, each with and without foot-support.Results: Seating condition did not affect head stability during reaching, but did affect kinematic reaching quality. The major reaching parameters, i.e., the proportion of reaches with one movement unit (MU) and the size of the transport MU, were not affected by foot-support. Forward-tilting had a positive effect on these parameters in children with US-CP, whereas the horizontal condition had this effect in children with BS-CP.Implications: A 15° forward-tilted seating and foot-support do not affect head stability. Reaching in children with US-CP profits from forward-tilting; in children with BS-CP forward-tilting worsens reaching - effects that are independent of foot-support. [ABSTRACT FROM AUTHOR]

Background: In typical development, postural adjustments during reaching change in the second half of infancy, including increasing rates of direction-specific adjustments. These changes are absent or different in infants at risk of cerebral palsy (CP). To discover whether these changes are related to acquisition of independent walking, we studied postural adjustments during reaching in infants before and after they learned to walk.Methods: Ten typically developing (TD) infants and 11 infants at very high risk (VHR) of CP were assessed before and after they learned to walk. Reaching movements were elicited during supported sitting, while surface electromyography was recorded of arm, neck, and trunk muscles. Percentages of direction-specific adjustments (first level of control), and recruitment patterns and anticipatory activation (second level of control) were calculated.Results: In both groups, postural adjustments during reaching were similar before and after acquisition of independent walking. Direction-specificity increased with age in typically developing infants but not in VHR-infants.Conclusion: Increasing age rather than the transition to independent walking is associated with increasing direction-specificity of TD-infants during reaching while sitting, while infants at very high risk of CP show no increase in direction-specificity, suggesting that they gradually grow into a postural deficit. [ABSTRACT FROM AUTHOR]

Background Children with cerebral palsy (CP) have impaired postural control. Posture is controlled in two levels: direction-specificity, and fine-tuning of direction-specific adjustments, including recruitment order. Literature suggests that direction-specificity might be a prerequisite for independent sitting. Aim To study development of postural adjustments in infants at very high risk for CP (VHR-infants) during developing the ability to sit independently. Method In a longitudinal study surface electromyograms of the neck-, trunk- and arm muscles of 11 VHR-infants and 11 typically developing (TD) infants were recorded during reaching in sitting before and after developing the ability to sit unsupported (median ages: VHR 8.0 and 14.9 months; TD 5.7 and 10.4 months). Sessions were video-recorded. Results In VHR- and TD-infants the prevalence of direction-specific adjustments and recruitment order did not change when the infant learned to sit independently. In VHR-infants able to sit independently more successful reaching was associated with a higher frequency of bottom-up recruitment (Spearman's rho = 0.828, p = 0.006) and a lower frequency of simultaneous recruitment (Spearman's rho = - 0.701, p = 0.035), but not with more direction-specificity. In TD-infants not able to sit independently, more successful reaching was associated with higher rates of direction-specific adjustments at the neck level (Spearman's rho = 0.778, p = 0.014), but not with recruitment order. Conclusions In VHR- and TD-infants postural adjustments during reaching in terms of direction-specificity and recruitment order are not related to development of independent sitting. Postural adjustments are associated with success of reaching, be it in a different way for VHR- and TD-infants. Clinical trial registration number: NTR1428. [ABSTRACT FROM AUTHOR]