title: Relevance of substantia nigra hyperechogenicity and reduced odor identification in idiopathic REM sleep behavior disorder.
abstract: BACKGROUND
  Substantia nigra (SN) hyperechogenicity determined by transcranial sonography (TCS) and olfactory dysfunction are common findings in Parkinson disease (PD), which may reveal a prodromal synucleinopathy in idiopathic REM sleep behavior disorder (iRBD).
  
  
  METHODS
  TCS and the Odor Stick Identification Test for Japanese (OSIT-J) were performed in 34 consecutive patients with iRBD (67.9+/-6.1years), 17 consecutive patients with PD (66.4+/-6.7years), and 21 control group subjects (64.4+/-5.8years).
  
  
  RESULTS
  There was a significantly increased area of echogenicity in the SN in the iRBD group (0.20+/-0.13cm2) and PD group (0.22+/-0.11cm2) compared with the control group (0.06+/-0.06cm(2)). We found pathological SN hyperechogenicity (0.20cm2) in 41.2% of the iRBD group, 52.6% of the PD group, and 9.5% of the control group. Further, there were abnormal findings of both pathological SN hyperechogenicity (0.20cm2) and functional anosmia or hyposmia in 4 (11.8%) or 9 (26.5%) of the iRBD group subjects, respectively, and 7 (57.9%) or 2 (11.8%) of the PD group subjects, respectively.
  
  
  CONCLUSIONS
  Pathological SN hyperechogenic abnormality and functional anosmia in iRBD may be a disease state in the transition to a neurodegenerative disease.
authors.affiliation: Department of Neurology, Center of Sleep Medicine, Dokkyo Medical University School of Medicine, Japan.
authors.forename: Masaoki
authors.initials: M
authors.lastname: Iwanami
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Hirata
authors.forename: Etsuo
authors.initials: E
authors.lastname: Takada
mesh_terms: D000368:Aged; D001143:Arousal / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D019636:Neurodegenerative Diseases / Q000453:epidemiology; D009812:Odorants; D000857:Olfaction Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis* / Q000453:epidemiology*; D013378:Substantia Nigra / Q000503:physiopathology*