Relation between proximal and distal proprioception in the upper limb in unilateral cerebral palsy using robotics

Abstract

Although clinical assessments suggest that children with unilateral cerebral palsy (uCP) experience proprioceptive difficulties, little is known about the relationship between proximal and distal proprioception in the upper limb (UL). Our aim was to investigate this relationship using robotics. Eighteen children with uCP (age=11y6m±2y9m, 10 males, 6 right-sided uCP) participated. Proximal proprioception was measured using the position matching task of the Kinarm Exoskeleton Robot. Distal proprioception was quantified with an active task, by moving their index finger to a position indicated on a tablet screen, and passive task, by specifying on a tablet screen the perceived location of their finger, using the ETH MIKE Robot. All tasks were performed without visual feedback. The relation between proximal and distal proprioception parameters was evaluated using Spearman's correlations (rs). For the affected UL, no significant correlations were found between proximal and active/passive distal proprioception (rs=0.11-(-0.34), p>0.17). Nevertheless, for the less-affected UL, distal proprioception during the active task showed a strong negative correlation with proximal proprioception (rs=-0.80, p<0.001), indicating that a better proximal proprioception corresponds to better distal proprioception. No significant correlations were found between passive distal and proximal proprioception in the less-affected UL (rs=-0.23-0.41, p>0.09). Quantitative measures of proximal and distal proprioception of the affected UL seem to be relatively independent in children with uCP. Possibly, the brain lesion affects distal proprioception more than proximal proprioception. However, for the less-affected UL, proximal and active distal proprioception seem to be interrelated. Future studies also including typically developing children could confirm these results.