title: Early dysfunctions of fronto-parietal praxis networks in Parkinson's disease.
abstract: In Parkinson's disease (PD) the prevalence of apraxia increases with disease severity implying that patients in early stages may already have subclinical deficits. The aim of this exploratory fMRI study was to investigate if subclinical aberrations of the praxis network are already present in patients with early PD. In previous functional imaging literature only data on basal motor functions in PD exists. Thirteen patients with mild parkinsonian symptoms and without clinically diagnosed apraxia and 14 healthy controls entered this study. During fMRI participants performed a pantomime task in which they imitated the use of visually presented objects. Patients were measured ON and OFF dopaminergic therapy to evaluate a potential medication effect on praxis abilities and related brain functions. Although none of the patients was apraxic according to De Renzi ideomotor scores (range 62-72), patients OFF showed significantly lower praxis scores than controls. Patients exhibited significant hyperactivation in left fronto-parietal core areas of the praxis network. Frontal activations were clearly dominant in patients and were correlated with lower individual praxis scores. We conclude that early PD patients already show characteristic signs of praxis network dysfunctions and rely on specific hyperactivations to avoid clinically evident apraxic symptoms. Subclinical apraxic deficits were shown to correlate with an activation shift from left parietal to left frontal areas implying a prospective individual imaging marker for incipient apraxia.
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.|MR Centre of Excellence, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Matt
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.|MR Centre of Excellence, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Foki
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.|MR Centre of Excellence, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Fischmeister
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Pirker
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.|NINDS Intramural Research Program, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Haubenberger
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.|MR Centre of Excellence, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Jakob
authors.initials: J
authors.lastname: Rath
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Johann
authors.initials: J
authors.lastname: Lehrner
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
authors.forename: Eduard
authors.initials: E
authors.lastname: Auff
authors.affiliation: Department of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria. roland.beisteiner@meduniwien.ac.at.|MR Centre of Excellence, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria. roland.beisteiner@meduniwien.ac.at.|Department of Neurology, MR Centre of Excellence, Medical University of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria. roland.beisteiner@meduniwien.ac.at.
authors.forename: Roland
authors.initials: R
authors.lastname: Beisteiner
mesh_terms: D001072:Apraxias / Q000209:etiology / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D018450:Disease Progression; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology; D010296:Parietal Lobe / Q000502:physiology*; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*
keywords: Apraxia; Dopaminergic therapy; Parkinson’s disease; Praxis network; fMRI