Dopa-responsive, Nonprogressive, Juvenile
Parkinsonism: Report of a Case
The most common variant of Parkinson syndrome (PS) is Lewy body Parkinson's disease (1-3), also known as idiopathic Parkinson's disease (PD) (4). Most PD cases manifest at approximately age 60 years (5,6), but between 5 and 10% have onset before age 40 years (6,7) and are classified as early-onset parkinsonism (EOP). The EOP has been divided into two subgroups: juvenile parkinsonism (JP), with onset before age 21 years, and young-onset PD (YOPD), whose onset is between ages 21 and 40 years (8). The largest proportion of EOP patients have PD (9-12). There are many pathologically verified YOPD cases in the literature (13), but autopsy studies of JP are rare. One familial JP case who had onset as dystonia had PD (14), whereas another familial case did not have Lewy body (LB) pathology (15). Both of these cases, however, had hypopigmented substantia nigra (SN) ( 1 4 3 ) .
An overlap between dystonia and PS is well known. Compared with late-onset PD, the EOP cases are more likely to manifest as dystonia ( 16). This association is stronger in Dopa-responsive dystonia (DRD) cases. Some DRD cases simultaneously develop parkinsonism whereas, in others, parkinsonism evolves later in the course of illness (17)(18)(19)(20). Family members of DRD cases may develop de novo PS later in life and have a benign course (17,20). JP and DRD (with or without PS) each has onset in childhood, and the initial levodopa (LD) response is comparable in these two disorders. The long-term response, however, is different and is helpful in distinguishing between the two.
As stated by Nygaard et al., ". . . it is the sustained, smooth, therapeutic response in patients with DRD that separates these disorders" (17). Regardless of the onset ~~ A videotape accompanies this article.