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PURPOSE: To investigate postural effects of the family-centered program, COPing with and CAring for infants with special needs (COPCA), applied at 3 to 6 months' corrected age in infants at high risk of cerebral palsy. Previously, we reported postural differences between the infants at risk of CP in the control group of the current study and a group of infants developing typically. Now we focus on differences between 2 intervention groups. METHODS: We explored postural adjustments during reaching in seated infants at 4, 6, and 18 months using surface electromyography of arm, neck, and trunk muscles. Infants randomly received the family-centered program or another infant physical therapy. Using videotaped intervention sessions, we investigated correlations between time spent on specific physical therapeutic actions and direction specificity, recruitment order, and anticipatory activation at 18 months. RESULTS: Postural adjustments in both groups were similar, but development of direction specificity and anticipatory activation in COPCA infants better mimicked typical development. These 2 parameters were associated with COPCA-type physical therapeutic actions. CONCLUSIONS: Postural control was similar after both interventions. Positive outcomes were associated with fewer intervening actions of the therapist and greater allowance of spontaneous movements.

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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.

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AIM: To investigate postural adjustments during reaching in infants at high risk for cerebral palsy (CP). METHOD: Observational cohort study in which 25 infants at high risk (11 males, 14 females) and 11 infants with typical development (six males, five females) were assessed at 4, 6, and 18 months corrected age. Reaching movements were elicited during supported and unsupported 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. Statistical analyses were performed with a binomial generalized estimating equations model for dichotomous variables and a linear mixed model for continuous variables. RESULTS: Postural activity of infants at high risk for CP at 4 months was virtually similar to that of infants with typical development. At 18 months, infants at high risk differed from infants with typical development with less direction-specificity (median values 20% vs 58% at trunk and neck level, OR 0.38, 95% CI 0.18-0.82); longer latencies to trunk muscle activation; and less anticipatory activation (41% vs 55%, in any direction-specific muscle, OR 0.53, 95% CI 0.32-0.89). In unsupported sitting, results were largely similar to those in supported sitting. INTERPRETATION: Infants at high risk for CP grew into a postural deficit: at 18 months they showed delayed development of direction-specificity, and postural dysfunction as evidenced by slower recruitment of postural muscles and less frequent anticipatory activation.

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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 14.9months; TD 5.7 and 10.4months). 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.

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Knowledge on the development of postural adjustments during infancy, in particular on the development of postural muscle coordination, is limited. This study aimed at the evaluation of the development of postural control during reaching in a supported sitting condition. Eleven typically developing infants participated in the study and were assessed at the ages of 4, 6, 10 and 18 months. We elicited reaching movements by presenting small toys at an arm's length distance, whilst activity of multiple arm, neck and trunk muscles was recorded using surface EMG. A model-based computer algorithm was used to detect the onset of phasic muscle activity. The results indicated that postural muscle activity during reaching whilst sitting supported is highly variable. Direction-specific postural activity was inconsistently present from early age onwards and increased between 10 and 18 months without reaching a 100 % consistency. The dominant pattern of activation at all ages was the 'complete pattern', in which all direction-specific muscles were recruited. At 4 months, a slight preference for top-down recruitment existed, which was gradually replaced by a preference for bottom-up recruitment. We conclude that postural control during the ecological task of reaching during supported sitting between 4 and 18 months of age is primarily characterized by variation. Already from 4 months onwards, infants are-within the variation-sometimes able to select muscle recruitment strategies that are optimal to the task at hand.

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