Motor Skills Disorder: Developmental Coordination Disorder

Children with developmental motor coordination struggle to perform accurately the motor activities of daily life, such as jumping, hopping, running, or catching a ball. Children with coordination problems may also agonize over using utensils correctly, tying their shoelaces, or writing. A child with developmental coordination disorder may exhibit delays in achieving motor milestones, such as sitting, crawling, and walking, because of clumsiness, and yet excel at verbal skills.

Children with developmental coordination disorder may resemble younger children because of their inability to master motor activities typical for their age group. For example, children with developmental coordination disorder in elementary school may not be adept at bicycle riding, skateboarding, running, skipping, or hopping. In the middle school years, children with this disorder may have trouble in team sports, such as soccer, baseball, or basketball. Fine motor skill manifestations of developmental coordination disorder typically include clumsiness using utensils and difficulty with buttons and zippers in the preschool age group. In older children, using scissors and more complex grooming skills, such as styling hair or putting on makeup, is difficult. Children with developmental coordination disorder are often ostracized by peers because of their poor skills in many sports, and they often have longstanding difficulties with peer relationships. Developmental coordination disorder is the sole disorder in the text revision of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) category motor skills disorder. Gross and fine motor impairment in this disorder cannot be explained on the basis of a medical condition, such as cerebral palsy, muscular dystrophy, or any other neuromuscular disorder.

EPIDEMIOLOGY

The prevalence of developmental coordination disorder has been estimated at about 5 percent of school-age children. The male-to-female ratio in referred populations tends to show increased rates of the disorder in males, but schools refer boys more often for testing and special education evaluations. Reports in the literature of the male-to-female ratio have ranged from 2:1 to as much as 4:1. These rates may also be inflated because motor behaviors in boys are scrutinized more closely than those in girls.

COMORBIDITY

Developmental coordination disorder is strongly associated with speech and language disorders. Children with coordination difficulties have higher-than-expected rates of speech and language disorders, and studies of children with speech disorders report very high rates of “clumsiness.” Some studies have found associations between fine motor skills in the upper arms and expressive and receptive language disorders, whereas gross motor problems and visual motor coordination problems were not associated with language disturbance. Developmental coordination disorder is also associated with reading disorders, mathematics disorder, and disorder of written expression. Higher-than-expected rates of attention-deficit/hyperactivity disorders (ADHD) are also associated with developmental coordination disorder.

ETIOLOGY

The causes of developmental coordination disorder are believed to include both “organic” and “developmental” factors. Risk factors postulated to contribute to this disorder include prematurity, hypoxia, perinatal malnutrition, and low birthweight. Prenatal exposure to alcohol, cocaine, and nicotine has also been hypothesized to contribute to both low birthweight and cognitive and behavioral abnormalities. Neurochemical abnormalities and parietal lobe lesions have also been suggested to contribute to coordination deficits. Developmental coordination disorder and communication disorders have strong associations, although the specific causative agents are unknown for both. Coordination problems are also more frequently found in children with hyperactivity syndromes and learning disorders. Recent studies of postural control, that is, the ability to regain balance after being in motion, indicate that children with developmental coordination disorder who do not have significant difficulties with balance when standing still are unable accurately to correct for movement, resulting in impaired balance compared with other children. A recent study concluded that, in children with developmental coordination disorder, signals from the brain to particular muscles (including the tibialis anterior and peroneus muscles) involved in balance are not being optimally sent or received. These findings have implicated the cerebellum as a contributing origin of dysfunction for developmental coordination disorder.

DIAGNOSIS

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