title: Normal 'heart' in Parkinson's disease: is this a distinct clinical phenotype?
abstract: Reduction of metaiodobenzylguanidine (MIBG) uptake has been observed in almost all patients with Parkinson's disease (PD), associated with hyposmia, orthostatic hypotension and rapid eye movement sleep behavioral disorder (RBD). In contrast, a subgroup of patients with PD with normal MIBG uptake have been reported to have milder disease and preserved cognition compared with those with lower MIBG. The aim of this study was to investigate whether non-motor manifestations of PD differ between patients with normal and abnormal myocardial MIBG uptake.
  
  
  
  Among 160 de-novo cases of PD, 44 had normal MIBG uptake. Twelve candidate non-motor features were evaluated using questionnaires and laboratory tests.
  
  
  
  Patients with decreased MIBG uptake had more constipation, RBD, cognitive impairment, hyposmia and orthostatic hypotension than did those with normal MIBG uptake. On linear regression analysis, orthostatic hypotension, olfactory function and probable RBD were significantly associated with MIBG uptake in PD. The principal component analysis showed that the group with normal MIBG was not associated with non-motor impairments.
  
  
  
  These results suggest that patients with PD with normal MIBG scans have a relatively low disease burden compared with those with abnormal MIBG. Fewer synuclein pathologies in the myocardia and sympathetic ganglia in PD with preserved MIBG uptake might be associated with lower threshold patterns of Braak synuclein pathology for non-motor manifestations compared with PD with decreased MIBG.
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: J-S
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: H-E
authors.initials: HE
authors.lastname: Park
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: I-S
authors.initials: IS
authors.lastname: Park
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Y-S
authors.initials: YS
authors.lastname: Oh
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: D-W
authors.initials: DW
authors.lastname: Ryu
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: I-U
authors.initials: IU
authors.lastname: Song
authors.affiliation: Department of Nuclear Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Y-A
authors.initials: YA
authors.lastname: Jung
authors.affiliation: Department of Nuclear Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: I R
authors.initials: IR
authors.lastname: Yoo
authors.affiliation: Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: H-S
authors.initials: HS
authors.lastname: Choi
authors.affiliation: Department of Neurology, Yonsei University School of Medicine, Seoul, Korea.
authors.forename: P H
authors.initials: PH
authors.lastname: Lee
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: K-S
authors.initials: KS
authors.lastname: Lee
mesh_terms: D019797:3-Iodobenzylguanidine / Q000378:metabolism; D000368:Aged; D003072:Cognition Disorders / Q000209:etiology / Q000523:psychology; D003248:Constipation / Q000209:etiology; D017281:Cost of Illness; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000209:etiology / Q000503:physiopathology; D010300:Parkinson Disease / Q000150:complications / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D020187:REM Sleep Behavior Disorder / Q000209:etiology; D019275:Radiopharmaceuticals / Q000378:metabolism
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine
keywords: Parkinson's disease; metaiodobenzylguanidine scintigraphy; non-motor features; normal cardiac sympathetic innervation