title: Differentiating drug-induced parkinsonism from Parkinson's disease: an update on non-motor symptoms and investigations.
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.
authors.affiliation: Divisione di Neurologia, Ospedale "Franz Tappeiner", Merano, Italy; Dipartimento di Scienze Neurologiche e del Movimento, Università di Verona, Italy. Electronic address: dr.francescobrigo@gmail.com.
authors.forename: Francesco
authors.initials: F
authors.lastname: Brigo
authors.affiliation: Dipartimento di Scienze Neurologiche e del Movimento, Università di Verona, Italy; Sobell Department of Motor Neuroscience and Movement Disorders, University College London (UCL) Institute of Neurology, London, United Kingdom.
authors.forename: Roberto
authors.initials: R
authors.lastname: Erro
authors.affiliation: Dipartimento di Scienze Neurologiche e del Movimento, Università di Verona, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Marangi
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, University College London (UCL) Institute of Neurology, London, United Kingdom.
authors.forename: Kailash
authors.initials: K
authors.lastname: Bhatia
authors.affiliation: Dipartimento di Scienze Neurologiche e del Movimento, Università di Verona, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Tinazzi
mesh_terms: D003937:Diagnosis, Differential; D006801:Humans; D010300:Parkinson Disease / Q000175:diagnosis*; D020734:Parkinsonian Disorders / Q000139:chemically induced* / Q000175:diagnosis*
keywords: Differential diagnosis; Dopamine transporter imaging; Drug-induced parkinsonism; Non-motor symptoms; Parkinson's disease; Transcranial sonography of the substantia nigra