Frontal white matter reductions in healthy males with complex stereotypies.

The pathophysiologic mechanism for stereotypic, bilateral repetitive movements involving the arms and hands (complex motor stereotypies) is unknown. This study used volumetric magnetic resonance imaging to compare cerebral lobes and caudate nucleus in six males with complex stereotypies and average intelligence to age-matched control subjects. Results indicated volumetric reductions in frontal white matter, disproportionate to total cerebral white volume, and in the left and right caudate nuclei. These preliminary data suggest a possible dysfunction of cortico-striatal-thalamo-cortical circuitry in children with nonautistic, physiologic motor stereotypies.