Assessment of Upper Limb Proprioception in Children with Developmental Coordination Disorder

Abstract

It has long been suspected that proprioceptive abnormalities underlie the motor problems in children with developmental coordination disorder (DCD). However, current empirical evidence of proprioceptive dysfunction in children with DCD is still inconsistent. To address this issue, this study pursued the following three aims: 1) To obtain objective measures of position sense acuity to verify that children with DCD have proprioceptive deficits. 2) To examine whether the proprioceptive abnormality in children with DCD is joint-specific or a generalized somatosensory deficit that affects distal as well as proximal joints. 3) To investigate the relationship between motor function and position sense acuity in children with and without DCD. Methods: Twenty children with DCD [(Mean age: 10 years 4 months (SD: 3 months); 9 ♂, 11♀) and thirty typically developing (TD) children [M age: 10 years 5 months (SD: 3 months); 14 ♂, 16♀] were recruited and screened using Movement Assessment Battery for Children (MABC-2). The DCD group had total MABC-2 score below 5th percentile, and TD group was above 25th percentile. Using a body-scalable wrist and elbow bimanual manipulandum, proprioceptive status was assessed using 1) a wrist and elbow joint position matching task requiring active movement to reproduce a target position with either the same or the opposite hand/forearm, and 2) a psychophysical two-alternate forced choice test for the wrist that relied on passive motion. It required children to discriminate between two joint positions. We measured both aspects of position sense acuity: bias and precision. Bias indicates the proximity of a sensed limb position corresponds to the true physical position of the limb. Precision represents the random error or the agreement between independent repeated responses and is thus a measure of response consistency. Results: First, in comparison to TD controls children with DCD exhibited a significantly lower position sense precision on both elbow (p < 0.05) and wrist (p < 0.001). Position sense bias during active joint position matching at either joint was not significantly higher in children with DCD. Second, the mean wrist position sense discrimination threshold for passive displacement was highly elevated in DCD group (+171%; p < 0.001). Third, position sense discrimination threshold correlated significantly with upper limb motor (r = -0.40) and balance scores (r= -0.50). Conclusion: This study documents that DCD is associated with a dysfunction of position sense. Furthermore, the proprioceptive dysfunction affected both proximal and distal upper limb joints in children with DCD, which is consistent with a view that proprioceptive dysfunction in DCD is generalized in nature. Given the substantial evidence that proprioceptive deficits degrade motor control, these sensory deficits may partly explain fine motor control impairment in DCD.