Effects of Symmetry and Age on Bilateral Upper-Limb Coordination in Children with Unilateral Cerebral Palsy.

Bilateral movements are important for daily function and are impaired in children with unilateral cerebral palsy (UCP). Prior work has established that coordination is dependent on symmetry demands between the limbs. We examined how symmetry impacted bilateral coordination, and as an exploratory aim, compared age-related differences in upper-limb (UL) coordination in children with UCP to children with typical development (TD). Using an instrumented cycling device, participants performed bilateral UL cycling in symmetric or asymmetric patterns. Metrics of inter-limb (phase error) coordination were compared between groups (TD or UCP) and with respect to age (young: 7-9 years; older: 13-15 years). Children with UCP had poorer inter-limb coordination in both symmetric (50.88°) and asymmetric (93.22°) bilateral tasks compared to TD children. Younger children, regardless of group, had poorer inter-limb coordination for the asymmetric (32.54°) bilateral task only. Regression modeling revealed UCP, age, and unilateral coordination ability were significantly associated with asymmetric bilateral coordination. The results indicate that bilateral coordination skills reflect atypical processes related to UCP and typical age-related motor development, particularly for more complex asymmetric tasks. Altogether, this research confirms children with UCP have impaired bilateral coordination and highlights potential for future work to study developmental changes in this population.