title: Hippocampal perfusion predicts impending neurodegeneration in REM sleep behavior disorder.
abstract: OBJECTIVE
  Patients with idiopathic REM sleep behavior disorder (IRBD) are at risk for developing Parkinson disease (PD) and dementia with Lewy bodies (DLB). We aimed to identify functional brain imaging patterns predicting the emergence of PD and DLB in patients with IRBD, using SPECT with (99m)Tc-ethylene cysteinate dimer (ECD).
  
  
  METHODS
  Twenty patients with IRBD were scanned at baseline during wakefulness using (99m)Tc-ECD SPECT. After a follow-up of 3 years on average, patients were divided into 2 groups according to whether or not they developed defined neurodegenerative disease (PD, DLB). SPECT data analysis comparing regional cerebral blood flow (rCBF) between groups assessed whether specific brain perfusion patterns were associated with subsequent clinical evolution. Regression analysis between rCBF and clinical markers of neurodegeneration (motor, color vision, olfaction) looked for neural structures involved in this process.
  
  
  RESULTS
  Of the 20 patients with IRBD recruited for this study, 10 converted to PD or DLB during the follow-up. rCBF at baseline was increased in the hippocampus of patients who would later convert compared with those who would not (p < 0.05 corrected). Hippocampal perfusion was correlated with motor and color vision scores across all IRBD patients.
  
  
  CONCLUSIONS
  (99m)Tc-ECD SPECT identifies patients with IRBD at risk for conversion to other neurodegenerative disorders such as PD or DLB; disease progression in IRBD is predicted by abnormal perfusion in the hippocampus at baseline. Perfusion within this structure is correlated with clinical markers of neurodegeneration, further suggesting its involvement in the development of presumed synucleinopathies.
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Canada. tt.dangvu@concordia.ca
authors.forename: Thien Thanh
authors.initials: TT
authors.lastname: Dang-Vu
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gagnon
authors.forename: Mélanie
authors.initials: M
authors.lastname: Vendette
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Soucy
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Postuma
authors.forename: Jacques
authors.initials: J
authors.lastname: Montplaisir
mesh_terms: D002560:Cerebrovascular Circulation; D005500:Follow-Up Studies; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D020961:Lewy Body Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D009410:Nerve Degeneration / Q000000981:diagnostic imaging / Q000503:physiopathology*; D059906:Neuroimaging; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D020187:REM Sleep Behavior Disorder / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods