Objective: To investigate functional dopaminergic impairments in dystonia, we compared patients with dystonia and Parkinson’s disease (PD) with normal controls using neuromelanin-sensitive magnetic resonance imaging (NM-MRI) and dopamine transporter single photon emission computed tomography (DAT SPECT).

Background: The pathogenesis of dystonia is remarkably diverse. Some types of dystonia, such as DYT5 (DYT-GCH1) and tardive dystonia, are related to dysfunction of the dopaminergic system. The cell loss in the substantia nigra (SN) of dystonia patients is reported on pathological examination [1], suggesting that impaired dopamine production may be involved both in DYT5 and in other types of dystonia.

Method: Eighteen generalized or segmental dystonia patients, 18 PD patients, and 27 healthy controls were examined using NM-MRI. DAT SPECT was performed on 17 patients with dystonia and eight patients with PD. Imaging data were compared in these patients and controls obtained from the database in Japanese healthy volunteers (n=256) [2] using the specific binding ratio (SBR).

Results: The mean area corresponding to NM in the SN (NM-SN) was 31±4.2 pixels in dystonia patients, 28±3.8 in PD patients, and 43±3.8 in controls. The mean SBR was 5.1±0.2 in dystonia patients, 2.8±0.2 in PD patients, and 9.2 (predictive) in controls. Both NM-SN area and SBR were inversely correlated with the Fahn-Marsden Dystonia Rating Scale. There was no significant difference between the dystonia and PD groups regarding NM-SN. In contrast, the SBR was lower ​​in PD than in dystonia patients.

Conclusion: Impairments of the dopaminergic system may be involved in the manifestation of dystonia symptoms in generalized and segmental dystonia. SN abnormalities in dystonia patients were supposed to be different from degeneration in PD patients.

References: (1) Iacono D, et al. Reduced number of pigmented neurons in the substantia nigra of dystonia patients? Findings from extensive neuropathologic, immunohistochemistry, and quantitative analyses. Tremor Other Hyperkinet Mov (N Y) 2015; 5: tre-5-301. (2) Matsuda H, et al. Japanese multicenter database of healthy controls for [123I] FP-CIT SPECT. Eur J Nucl Med Mol Imaging 2018; 45: 1405-1416.

« Back to MDS Virtual Congress 2021

MDS Abstracts - https://www.mdsabstracts.org/abstract/is-generalized-and-segmental-dystonia-accompanied-by-impairments-of-the-dopaminergic-system/