[The clinical characteristics of involuntary movements in childhood].

The basal ganglia play important roles in the pathophysiology of various types of involuntary movement disorders, such as chorea, ballism, athetosis, dystonia, tremor and tics. These involuntary movements when occur in the childhood show the specific ages of onset and the courses. For example postural dystonia occurs in childhood but action dystonia tend to occur in later ages. Postural tremor occurs after the second decades but resting tremor does not occur in childhood. Furthermore drug induced dystonia but not levodopa induced dyskinesia occurs in childhood. The age dependent clinical features observed in these involuntary movements are thought to be due to the specific developmental processes of the pathway in the basal ganglia and its efferent projections, which are involved in the pathophysiology in the each disorder. For example, the dopamine activity is known to be increased in the striatum before ten years of age which decreases, rapidly during the first decade and further decreases in the next decade with the moderate degree till adult level. The direct pathway, which is predominant in the ventral area in the basal ganglia, matures earlier than the indirect pathway, which is predominant in the dorsal area. In this paper the pathophysiologies of the hereditary progressive dystonia with marked diurnal fluctuation, juvenile parkinsonism, idiopathic torsion dystonia, chorea, ballismus and tics, all of which occur in the childhood, are discussed from the view point of the age dependent specificities of the involved pathways in the basal ganglia and their projections during development.