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Positron emission tomographic studies of dopa‐responsive dystonia and early‐onset idiopathic parkinsonism
Author(s) -
Snow Barry J.,
Nygaard Torbjoern G.,
Takahashi Hirohide,
Calne Donald B.
Publication year - 1993
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410340518
Subject(s) - parkinsonism , dystonia , positron emission tomography , medicine , computed tomographic , pediatrics , nuclear medicine , neuroscience , psychiatry , psychology , radiology , pathology , computed tomography , disease
There are two major syndromes presenting in the early decades of life with dystonia and parkinsonism: dopa‐responsive dystonia (DRD) and early‐onset idiopathic parkinsonism (EOIP). DRD presents predominantly in childhood with prominent dystonia and lesser degrees of parkinsonism. EOIP presents before age 40 with parkinsonism (often with associated dystonia). Both disorders are exquisitely sensitive to levodopa, although the long‐term prognosis in each appears to be different. Some have suggested, however, that DRD is a form of EOIP. We performed positron emission tomography with 6‐fluorodopa in 10 patients with DRD and 18 patients with EOIP to study the integrity of their nigrostriatal dopaminergic systems. In DRD, we found normal striatal FD uptake. In contrast, patients with EOIP had reduced striatal FD uptake. We conclude that the pathophysiologies of DRD and EOIP are distinct. Although both disorders presumably represent a deficiency of striatal dopamine, the results suggest that in DRD dopa uptake, decarboxylation, and storage mechanisms are intact. This may explain the sustained response of DRD to low doses of levodopa. 6‐Fluorodopa positron emission tomography distinguishes DRD from EOIP.