Developmental Coordination Disorder: A Pilot Diffusion Tensor Imaging Study

Abstract

Motor deficits associated with developmental coordination disorder are not attributable to macrostructural brain abnormalities, but differences in brain microstructure may exist. Using diffusion tensor imaging, we explored the integrity of motor, sensory, and cerebellar pathways in children with and without developmental coordination disorder. In seven children with the disorder and nine typically developing children (aged 8-12 years), we measured diffusivity and fractional anisotropy of the corticospinal tract, posterior thalamic radiation, and superior and middle cerebellar peduncles. Fractional anisotropy of motor and sensory tracts and diffusion parameters in cerebellar peduncles did not differ between groups. Mean diffusivity of the corticospinal tract and posterior thalamic radiation was lower in children with developmental coordination disorder compared with control children (P < 0.04 and P < 0.06, respectively). Results were driven by lower axial diffusivity, which was significantly correlated with motor impairment scores on the Movement Assessment Battery for Children-2 for both the corticospinal tract (r = 0.56, P = 0.03) and posterior thalamic radiation (r = 0.70, P = 0.003). Reduced axial diffusivity in motor and sensory tracts may be implicated in developmental coordination disorder, but replication in a larger study is needed to confirm these findings.

Introduction

Developmental coordination disorder affects approximately 5% of school-age children. It is a motor disorder of unknown etiology that significantly interferes with a child’s ability to perform activities of daily living [1]. Children with developmental coordination disorder struggle to complete self-care and academic tasks that require fine motor coordination. They may also experience difficulty with gross motor tasks, such as catching a ball or riding a bike. Central nervous system pathology is thought to underlie the disorder, but has only recently been a source of investigation. Recent studies indicated differences in patterns of brain activation in children with developmental coordination disorder, compared with typically developing children [2], [3], [4], [5]. Studies have been limited to functional magnetic resonance imaging. However, other neuroimaging studies of children with developmental coordination disorder are key to a better understanding of the neurobiology underlying this disorder. In the absence of evidence for brain macrostructural differences in children with developmental coordination disorder, differences may exist at the microstructural level, which can now be measured with advanced neuroimaging techniques such as diffusion tensor imaging.

This pilot study sought to explore the integrity of motor, sensory, and cerebellar pathways, using diffusion tensor imaging in children with and without developmental coordination disorder. The major voluntary motor pathway, the corticospinal tract, and the sensory pathway from the posterior thalamic radiation have been implicated in other motor disorders, such as cerebral palsy [6]. Compared with typically developing children, children with cerebral palsy exhibited lower water diffusion along the length of their axons, and this finding was significantly correlated with functional levels on the Gross Motor Function Classification System [6]. In addition to the corticospinal tract and posterior thalamic radiation, we explored cerebellar pathways, given the hypothesized role of the cerebellum in developmental coordination disorder [7]. We selected the middle cerebellar peduncle because it carries pathways associated with the initiation, planning, and timing of motor activity [8], all thought to be affected in developmental coordination disorder [9]. We also traced the superior cerebellar peduncle because it contains pathways that carry information from the cerebellum to the primary motor and premotor areas of the cortex [8]. We hypothesized that children with developmental coordination disorder would demonstrate different diffusion parameters in each of these motor, sensory, and cerebellar pathways, compared with typically developing children.