Affiliations: Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
Correspondence:
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Correspondence to: Lana Chahine, MD, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA. Tel.: +1 412 692 4600; Fax: +1 412 692 4907; E-mail: [email protected].
Abstract: Background:In patients with early parkinsonism, misdiagnosis may occur in >30% of cases. This can have detrimental consequences clinically and in clinical trials. Dopamine transporter (DAT) SPECT imaging can help improve diagnostic accuracy. Objective:To describe characteristics of individuals initially diagnosed with idiopathic Parkinson’s disease (iPD) and with abnormal DAT SPECT imaging who had a change in diagnosis on follow-up. Methods:Data were obtained from the biomarker study Parkinson’s Progression Markers Initiative (PPMI). PPMI is a multicenter, observational study that enrolled 423 individuals with a diagnosis of iPD of ≤2 years duration and with abnormal DAT SPECT imaging. Participants were assessed at least annually, and diagnosis was documented by the site neurologist. Characteristics of those that had a change in diagnosis were compared to those with stable diagnosis. Results:390 subjects were included. Eight (2%) had a change in diagnosis. The diagnosis was changed to multiple system atrophy in 5 cases, dementia with Lewy bodies in 2, and corticobasal degeneration in 1. Revision of diagnosis occurred 2–5.2 years from enrollment. Mean motor score was higher (26.9 vs 20.6; p = 0.01), DAT binding lower (1.056 vs 1.406; p = 0.01), genetic risk score lower (–0.016 vs –0.022; p = 0.0470), and olfaction score higher (28.75 vs 22.05; p = 0.03) in those whose diagnosis changed compared to those who did not. Conclusion:Diagnosis remained stable in most individuals with early parkinsonism diagnosed with iPD and with abnormal DAT imaging. A small number had a revision in diagnosis. Clinical and biomarker abnormalities were greater at baseline in those whose diagnosis changed.
Keywords: Parkinson’s disease, parkinsonism, movement disorders, SPECT, DAT scan, multiple system atrophy, atypical parkinsonism
