title: Vulnerability of the nigrostriatal system as detected by transcranial ultrasound.
abstract: OBJECTIVE
  To assess the incidence of a hyperechogenic substantia nigra (SN) by transcranial sonography (TCS) in healthy people and to evaluate whether an enlarged hyperechogenic SN area is associated with functional impairment of the nigrostriatal system.
  
  
  METHODS
  Until now, preclinical impairment of the nigrostriatal system could be identified only by functional neuroimaging techniques such as PET in selected groups of patients. TCS is a new, noninvasive ultrasound technique that has demonstrated an increased echogenicity of the SN in patients with PD, whereas in most healthy individuals, the SN is either barely detectable or undetectable by TCS.
  
  
  RESULTS
  Of 330 healthy volunteers, 8.6% exhibited an increased echogenicity of the SN. From these, 10 clinically healthy individuals with distinct unilateral or bilateral hyperechogenic signals in the SN region (SN area above 0.25 cm2) underwent comprehensive motor testing, neuropsychological assessment, MRI, and [18F]-dopa PET examination. With regard to motor functions, these individuals did not differ from 10 age- and sex-matched controls with a low echogenic SN and an area of echogenic signals below 0.2 cm2. Enlargement of hyperechogenic areas in the 10 healthy individuals was associated with a marked decrease in the accumulation of [15F]-dopa in the caudate nucleus and putamen.
  
  
  CONCLUSIONS
  Substantia nigra hyperechogenicity appears to indicate a functional impairment of the nigrostriatal system. Transcranial sonography may be a suitable method of identifying persons at risk of nigrostriatal alterations, making possible the introduction of early neuroprotective therapy.
authors.affiliation: Department of Neurology, Bayerische Julius-Maximilians-Universität Würzburg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Berg
authors.forename: G
authors.initials: G
authors.lastname: Becker
authors.forename: B
authors.initials: B
authors.lastname: Zeiler
authors.forename: O
authors.initials: O
authors.lastname: Tucha
authors.forename: E
authors.initials: E
authors.lastname: Hofmann
authors.forename: M
authors.initials: M
authors.lastname: Preier
authors.forename: P
authors.initials: P
authors.lastname: Benz
authors.forename: W
authors.initials: W
authors.lastname: Jost
authors.forename: K
authors.initials: K
authors.lastname: Reiners
authors.forename: K W
authors.initials: KW
authors.lastname: Lange
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002421:Caudate Nucleus / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007223:Infant; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D013378:Substantia Nigra / Q000000981:diagnostic imaging* / Q000473:pathology; D014055:Tomography, Emission-Computed; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*