title: Echogenicity of the substantia nigra: association with increased iron content and marker for susceptibility to nigrostriatal injury.
abstract: BACKGROUND
  Patients with Parkinson disease characteristically exhibit an increased echogenicity of the substantia nigra (SN) on transcranial sonography, a new neuroimaging technique. The same echo feature of the SN can be identified in 9% of healthy adults.
  
  
  OBJECTIVE
  To evaluate the relevance of the echogenic SN in healthy adults.
  
  
  METHODS
  In the first part of the study, 10 healthy subjects younger than 40 years with a distinct SN hyperechogenicity underwent extensive neurological, motor, neuropsychological, and fluorine 18-dopa positron emission tomographic ([18F]-dopa PET) examinations. Results were compared with those of 10 subjects with a low echogenic SN. In the second part of the study, the postmortem brains of 20 patients without extrapyramidal disorders during their lifetime were sonographically examined with a particular focus on SN echogenicity. Subsequently, one half of the brain was prepared for heavy metal analysis, the other for a histological examination.
  
  
  RESULTS
  Healthy subjects with SN hyperechogenicity exhibited a significant reduction of the [18F]-dopa uptake, especially in the putamen (Wilcoxon matched pair test: left side, P =.006; right side, P =.009), whereas their neuropsychological and motor performance were normal. Postmortem studies showed that the echogenicity of the SN correlated with its iron content.
  
  
  CONCLUSIONS
  Increased echogenicity of the SN, characteristically seen in Parkinson disease, is related to a functional impairment of the nigrostriatal system (even in young healthy adults) that can be revealed by [18F]-dopa PET studies. Substantia nigra hyperechogenicity is related to a higher tissue iron level, which is known to enhance the cells' generation of reactive oxygen specimens. Therefore, we hypothesize that transcranial sonography may identify a susceptibility marker for the development of nigral injury that can be detected early in life, prior to the onset of Parkinson disease.
authors.affiliation: Department of Neurology, University of Würzburg, Josef-Schneider-Str 11, 97080 Würzburg, Germany. daniela.berg@mail.uni-wuerzburg.de
authors.forename: Daniela
authors.initials: D
authors.lastname: Berg
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Roggendorf
authors.forename: Ute
authors.initials: U
authors.lastname: Schröder
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Klein
authors.forename: Thomas
authors.initials: T
authors.lastname: Tatschner
authors.forename: Peter
authors.initials: P
authors.lastname: Benz
authors.forename: Oliver
authors.initials: O
authors.lastname: Tucha
authors.forename: Michael
authors.initials: M
authors.lastname: Preier
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Lange
authors.forename: Karlheinz
authors.initials: K
authors.lastname: Reiners
authors.forename: Manfred
authors.initials: M
authors.lastname: Gerlach
authors.forename: Georg
authors.initials: G
authors.lastname: Becker
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis / Q000737:chemistry; D003342:Corpus Striatum / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006801:Humans; D007501:Iron / Q000032:analysis / Q000378:metabolism*; D008297:Male; D011180:Postmortem Changes; D018709:Statistics, Nonparametric; D013378:Substantia Nigra / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*; D014055:Tomography, Emission-Computed / Q000379:methods / Q000706:statistics & numerical data; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods / Q000706:statistics & numerical data
chemical_list: D015415:Biomarkers; D007501:Iron