title: Dopamine transporter imaging in essential tremor with and without parkinsonian features.
abstract: Mild parkinsonian features can be observed in patients with essential tremor (ET). Although dopamine transporter (DAT) imaging is usually normal in ET, some studies found mild dopaminergic deficit in ET patients compared to healthy controls (HC). We analyzed clinical and DAT imaging data in ET patients with and without parkinsonian features. Thirty-nine ET patients with and without parkinsonian features and 13 HC underwent detailed examination by a movement disorders neurologist and 123-I ioflupane SPECT. Two independent radiologists "blinded" to the clinical diagnosis analyzed images visually and by semi-quantitative calculation of striatal binding ratios in different volumes of interests. ET patients were divided into pure ET group (no parkinsonian features, n = 22), ET-P [one parkinsonian feature not sufficient for the clinical diagnosis of Parkinson's disease (PD), n = 9], and ET + PD (two or more parkinsonian features meeting diagnostic criteria for PD, n = 8). As expected, ET + PD patients had the lowest striatal binding ratios. We also found a trend toward slightly lower striatal binding ratios in ET patients ET compared to HC, especially in caudate nucleus. There was no significant correlation between striatal binding ratios, ET severity or duration. Patients with ET and parkinsonian features represent a heterogeneous group that includes ET + PD and ET-P. The latter group shares some clinical features with PD but has no dopaminergic deficit on DAT imaging as determined by visual image interpretation. On the other hand, minimal dopaminergic deficit (as compared to controls) is detected in some ET patients with semi-quantitative image analysis, although the pattern may be different from that of PD.
authors.affiliation: Department of Neurology, Methodist Neurological Institute, Houston, TX, USA. walnmd@yahoo.com.
authors.forename: Olga
authors.initials: O
authors.lastname: Waln
authors.affiliation: Department of Radiology, NorthShore University Health System, Evanston, IL, USA.|Department of Radiology, Pritzker School of Medicine, Chicago, IL, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Radiology, NorthShore University Health System, Evanston, IL, USA.|Department of Radiology, Pritzker School of Medicine, Chicago, IL, USA.
authors.forename: Reid
authors.initials: R
authors.lastname: Perlman
authors.affiliation: Department of Radiology, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Juliet
authors.initials: J
authors.lastname: Wendt
authors.affiliation: Department of Radiology, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Anh K
authors.initials: AK
authors.lastname: Van
authors.affiliation: Department of Neurology, Parkinson's Disease Center and Movement Disorder Clinic, Baylor College of Medicine, 7200 Cambridge, Suite 9A, MS: BCM 609, Houston, TX, 77030-4202, USA. josephj@bcm.edu.
authors.forename: Joseph
authors.initials: J
authors.lastname: Jankovic
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D001931:Brain Mapping; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D020329:Essential Tremor / Q000150:complications* / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009662:Nortropanes; D020734:Parkinsonian Disorders / Q000150:complications* / Q000000981:diagnostic imaging / Q000378:metabolism*; D019275:Radiopharmaceuticals; D012720:Severity of Illness Index; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D009662:Nortropanes; D019275:Radiopharmaceuticals; C493214:SLC6A3 protein, human; C519528:ioflupane
keywords: Dopamine transporter imaging; Essential tremor; Parkinson’s disease