Impaired Automatic Arm Movements in Obstetric Brachial Plexus Palsy Suggest a Central Disorder

Abstract

The authors aimed to find evidence for a central component of the impairment of movement of the affected arm in children with obstetric brachial plexus palsy. The authors performed a cross-sectional study in 19 children (median age 5 years) with obstetric brachial plexus palsy who were able to voluntarily abduct their affected arm beyond 90 degrees. They were asked to perform 4 tasks designed to provoke automatic arm movements to maintain balance. The authors assumed automatic motor programming to be impaired when 2 of 3 investigators agreed using video recordings that the affected arm did not abduct beyond 90 degrees while the unaffected arm did. Children abducted the affected arm less often than the healthy one (generalized binary logistic model of all 4 tasks, P = .001). The deficit during automatic arm abduction was not observed during voluntary movements and therefore cannot be explained by a peripheral deficit, suggesting a central component.