[Definition and nosological concept of juvenile parkinsonism].

Clinicopathological identification of juvenile parkinsonism(JP) was described in reference to Dopa-responsive syndrome or to dopamine-dependent disorders. Recently, hereditary progressive dystonia(HPD), a dopamine-dependent disorder, was identified as a nosological entity from JP and Parkinson's disease(PD) by discovery of mutations of the gene. JP includes young onset Parkinson's disease(YOPD) and idiopathic JP with much younger-onset cases. YOPD belongs to PD-nosology based on clinical and pathological findings of our own autopsied cases. However, the idiopathic JP' might involve independent pathophysiological changes. Namely, cases of the JP are associated with atypical pathological findings with lack of Lewy body or hypoplasia of the substantia nigra and specific clinical manifestations of autosomal recessive trait and of dystonic feature and diurnal fluctuation of the symptoms.