title: Evaluation of parkinsonism and striatal dopamine transporter loss in patients with spinocerebellar ataxia type 6.
abstract: It is unclear whether patients with spinocerebellar ataxia type 6 (SCA6) have parkinsonism and striatal dopamine transporter (DAT) loss, based on previously small size studies without well-matched controls. A study with a larger number of patients and both age- and gender-matched healthy controls (HCs) is needed for a better answer to this question. Twelve genetically confirmed ataxic SCA6 patients (six male six female, age 65.3 ± 11.2 years), and eight age- and gender-matched HCs (five male three female, age 71.3 ± 8.6 years) were enrolled during 2013-2015 from tertiary movement disorders and ataxia clinics. Clinical assessment for parkinsonism, and qualitative and quantitative assessment of DAT level on DaTscan™ imaging were conducted in SCA6 patients compared to HCs. We found no convincing parkinsonism in SCA6 patients, given generalized bradykinesia in the context of significant ataxia in all, with mild symmetric rigidity in five without resting tremor. Furthermore, we found no striatal DAT loss in anterior, posterior, and total putamen and caudate on imaging, assessed independently by qualitative visual inspection in a blinded manner by the nuclear medicine specialist and movement disorder specialist (kappa = 1). Additional quantitative analysis on these areas did not reveal significant DAT loss either in SCA6 patients compared to HCs. We conclude that there is no convincing parkinsonism or DAT loss in SCA6 patients in this unique study with a larger than previously reported number of patients compared to both age- and gender-matched HCs, suggesting that dopaminergic dysfunction is not usually involved in SCA6.
authors.affiliation: Department of Neurology, University of Chicago, 5841 S. Maryland Ave., MC 2030, Chicago, IL, 60637, USA. txie@neurology.bsd.uchicago.edu.
authors.forename: Tao
authors.identifier: http://orcid.org/0000-0001-9551-6613
authors.initials: T
authors.lastname: Xie
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, University of Chicago, Chicago, IL, 60637, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Appelbaum
authors.affiliation: Department of Neurology, University of Chicago, 5841 S. Maryland Ave., MC 2030, Chicago, IL, 60637, USA.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Bernard
authors.affiliation: Department of Neurology, University of Chicago, 5841 S. Maryland Ave., MC 2030, Chicago, IL, 60637, USA.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Padmanaban
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, University of Chicago, Chicago, IL, 60637, USA.
authors.forename: Yonglin
authors.initials: Y
authors.lastname: Pu
authors.affiliation: Department of Neurology, University of Chicago, 5841 S. Maryland Ave., MC 2030, Chicago, IL, 60637, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Gomez
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015220:Calcium Channels / Q000235:genetics; D016022:Case-Control Studies; D003342:Corpus Striatum; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D020734:Parkinsonian Disorders / Q000150:complications*; D049268:Positron-Emission Tomography; D020754:Spinocerebellar Ataxias / Q000150:complications* / Q000235:genetics; D018911:Trinucleotide Repeats / Q000235:genetics; D020864:Calcium Channels, N-Type
chemical_list: D015220:Calcium Channels; D050483:Dopamine Plasma Membrane Transport Proteins; C105656:CACNA1A protein, human; D020864:Calcium Channels, N-Type
keywords: Dopamine transporter; Parkinsonism; SCA6; Spinocerebellar ataxia