Review
Differentiating drug-induced parkinsonism from Parkinson's disease: An update on non-motor symptoms and investigations

https://doi.org/10.1016/j.parkreldis.2014.05.011Get rights and content
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Highlights

  • Clinical differentiation between DIP and PD can be challenging.

  • Their distinction has crucial implications in terms of management and prognosis.

  • Hyposmia can differentiate between DIP and PD unmasked by anti-dopaminergic drugs.

  • Sympathetic cardiac scintigraphy might predict dopaminergic pathway abnormalities.

  • Dopamine transporter imaging has high accuracy in differentiating between DIP and PD.

Abstract

Drug-induced parkinsonism is the second most common cause of parkinsonism after Parkinson's disease and their distinction has crucial implications in terms of management and prognosis. However, differentiating between these conditions can be challenging on a clinical ground, especially in the early stages. We therefore performed a review to ascertain whether assessment of non-motor symptoms, or use of ancillary investigations, namely dopamine transporter imaging, transcranial sonography of the substantia nigra, and scintigraphy for myocardial sympathetic innervation, can be recommended to distinguish between these conditions.

Among non-motor symptoms, there is evidence that hyposmia can differentiate between patients with “pure” drug-induced parkinsonism and those with degenerative parkinsonism unmasked by an anti-dopaminergic drug. However, several issues, including smoking history and cognitive functions, can influence smell function assessment. Higher diagnostic accuracy has been demonstrated for dopamine transporter imaging. Finally, preliminary evidence exists for sympathetic cardiac scintigraphy to predict dopaminergic pathway abnormalities and to differentiate between drug-induced parkinsonism and Parkinson's disease.

Imaging of the dopaminergic pathway seems to be the only, reasonably available, technique to aid the differential diagnosis between drug-induced parkinsonism and Parkinson's disease.

Keywords

Differential diagnosis
Dopamine transporter imaging
Drug-induced parkinsonism
Non-motor symptoms
Parkinson's disease
Transcranial sonography of the substantia nigra

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Editor's comment: Differentiating drug-induced parkinsonism (DIP) from Parkinson's disease (PD) can be a difficult and frustrating exercise for both patient and physician. To make matters even more difficult, individuals with incipient PD may be more prone to develop DIP because of already reduced dopaminergic reserve. Thus, this very useful review by Brigo and colleagues cogently summarizes the information available regarding the usefulness of various approaches and procedures in separating these two entities. They describe the value of some nonmotor features of PD, especially olfactory dysfunction, in distinguishing between PD and DIP. They also provide very useful information on which procedures are useful (DaT-scan and MIBG scanning) and which do not seem to be (transcranial sonography of the substantia nigra) in making this differentiation.

Ronald F. Pfeiffer, Editor-in-Chief Department of Neurology, University of Tennessee HSC, 855 Monroe Avenue, Memphis, TN 38163, USA.

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These authors contributed equally to the manuscript.