Does somatosensory function relate to bimanual function in children with unilateral cerebral palsy?

Background Goal-directed bimanual movements rely on the integration of somatosensory information to plan and adjust motor actions. In children with unilateral cerebral palsy (uCP), previous studies have primarily relied on clinical assessments of bimanual function and proprioception, whereas robotic and instrumented assessments may provide more precise and objective measures to further outline this relationship. Objectives To investigate the association between tactile registration, tactile perception, proprioception and bimanual function in children with uCP, using both clinical and instrumented assessments. Methods In this cross-sectional study, sixty-one children with uCP (mean age 11y11mo (SD 3y0mo); 35 males) completed assessments of tactile registration, tactile perception and proprioception. Bimanual function was evaluated through functional hand use (Assisting Hand Assessment; Children’s Hand-Use Experience Questionnaire), bimanual dexterity (Tyneside pegboard Test) and bimanual coordination (Ball-on-Bar task on the Kinarm robot; Box opening task). Associations were investigated using correlations (r/r _s ) and multiple linear regressions (R²). Results Worse tactile registration was weakly associated with reduced functional hand use (rₛ=-0.320-(-0.408), p  ≤ 0.032). Worse tactile perception showed low to moderate associations with reduced functional hand use ( r ₛ=-0.348-(-0.626), p  ≤ 0.023), slower bimanual dexterity ( r ₛ=-0.478-(-0.574), p  < 0.001) and poorer coordination (| r ₛ|=0.357–0.501, p  < 0.022). Proprioceptive impairments were generally lowly to moderately related to functional hand use ( r ₛ=-0.236-(-0.493), p  < 0.113) and bimanual dexterity ( r ₛ=0.279–0.509, p  < 0.095). Regression analyses indicated that two-point discrimination, distal position sense and proximal position sense explained respectively 33–40% and 58% of the variance in functional hand use ( p  < 0.050) and of bimanual dexterity ( p  < 0.050). Variability in bimanual coordination was only minimally explained by proprioceptive measures (R²=4%-9%, p  = 0.024–0.081). Conclusions Higher-order tactile perception and proprioception are particularly relevant for functional hand use and bimanual dexterity in children with uCP, whereas associations with bimanual coordination are more task- and parameter dependent. The results emphasize the importance of integrating somatosensory assessments into the follow-up of children with uCP to further understand bimanual impairments.