title: Differentiation of Parkinson's disease and multiple system atrophy in early disease stages by means of I-123-MIBG-SPECT.
abstract: BACKGROUND
  Differential diagnosis between idiopathic Parkinson's disease (PD) and multiple system atrophy (MSA) is often difficult in early disease stages. Since MSA is misdiagnosed as PD in more than 20% of the early stages, there is need for methods refining the differentiation of the two disease entities. In PD postganglionic involvement of the autonomic nervous system (ANS) predominates whereas in MSA the ANS is mainly affected in its preganglionic structures. The functional integrity of postganglionic cardiac sympathetic neurons can be investigated using I-123-metaiodobenzylguanidine-single photon emission computed tomography (MIBG-SPECT).
  
  
  OBJECTIVE
  We investigated whether I-123-MIBG-SPECT allows to differentiate between early stages of PD and MSA in patients not yet requiring L-dopa therapy.
  
  
  METHODS
  Thirty patients (10 PD and 20 MSA patients) underwent MIBG-SPECT and evaluation of heart rate variability (HRV). Patients on any medication interfering with MIBG-accumulation were excluded from the study. Cardiac perfusion was evaluated by myocardial scintigraphy.
  
  
  RESULTS
  The median cardiac MIBG uptake was significantly decreased in PD as well as MSA patients compared to controls (P<0.001). However, in the PD group MIBG uptake was significantly lower than in MSA (P=0.03). Even in PD patients without clinical signs of autonomic failure, MIBG uptake was significantly lower than in MSA patients (P=0.03). Analysis of heart rate parameters did not differentiate between PD and MSA patients. The median coefficient of variation was significantly smaller in PD and MSA patients compared to control subjects.
  
  
  CONCLUSIONS
  Our study shows that MIBG-SPECT identifies autonomic cardiac dysfunction in very early stages of both, PD and MSA. More importantly, the technique facilitates differentiation of MSA and PD in the early stages. The different pathology with prominent peripheral, postganglionic sympathetic dysfunction in PD and primarily central and preganglionic lesions in MSA accounts for a lower MIBG uptake in PD compared to MSA patients.
authors.affiliation: Department of Neurology, University Erlangen-Nuernberg, Schwabachanlage 6, 91054, Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Druschky
authors.forename: M J
authors.initials: MJ
authors.lastname: Hilz
authors.forename: G
authors.initials: G
authors.lastname: Platsch
authors.forename: M
authors.initials: M
authors.lastname: Radespiel-Tröger
authors.forename: K
authors.initials: K
authors.lastname: Druschky
authors.forename: T
authors.initials: T
authors.lastname: Kuwert
authors.forename: B
authors.initials: B
authors.lastname: Neundörfer
mesh_terms: D000328:Adult; D000368:Aged; D018450:Disease Progression; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D017779:Sympathetic Fibers, Postganglionic / Q000000981:diagnostic imaging / Q000503:physiopathology; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon