Motor adaptation in children with myelomeningocele: comparison to children with ADHD and healthy siblings.

Myelomeningocele is a common developmental malformation of the central nervous system that usually results in motor deficits. Previous studies of myelomeningocele have not examined motor adaptation, which involves changes in the control of movements that occur as a result of repeated task exposure but do not depend on conscious recall of the exposure. We studied motor adaptation in 17 children with myelomeningocele and shunted hydrocephalus, 19 children with attention deficit/hyperactivity disorder (ADHD), and 20 healthy siblings. All children were 8 to 15 years of age. They were administered 2 measures of motor adaptation known to be sensitive to subcortical abnormalities in adult neurological disorders. One task assessed the biasing in weight judgments that occurs after exposure to heavy versus light weights, and the other assessed the adaptation in reaching movements that occurs when vision is laterally displaced by prisms. Contrary to expectations, the groups did not differ in motor adaptation. Children in all 3 groups displayed significant biasing in their weight judgments and improvement in the accuracy of pointing during prism adaptation trials. Performance on the 2 motor adaptation tasks was not related to age or IQ. Weight biasing was positively related to a measure of response disinhibition. The findings suggest that myelomeningocele does not result in global impairment of motor skills, but instead in a profile of intact and impaired motor functions that potentially may be decomposed in accordance with the neuroscience of motor skills.