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Echogenicity of the Substantia Nigra
Association With Increased Iron Content and Marker for Susceptibility to Nigrostriatal Injury
Daniela Berg, MD;
Wolfgang Roggendorf, MD;
Ute Schröder;
Rüdiger Klein, MD;
Thomas Tatschner, MD;
Peter Benz, MD;
Oliver Tucha, PhD;
Michael Preier, MSc;
Klaus W. Lange, MD;
Karlheinz Reiners, MD;
Manfred Gerlach, PhD;
Georg Becker, MD
Arch Neurol. 2002;59:999-1005.
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.
Design 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.
From the Department of Neurology (Drs Berg and Reiners), Division of
Neuropathology (Drs Roggendorf and Klein), Institute for Forensic Medicine
(Dr Tatschner), and Department of Psychiatry (Dr Gerlach), Bayerische Julius-Maximilians-Universität
Würzburg, Würzburg, Germany, the Department of Neurology, University
of Homburg, Saar, Germany (Dr Becker and Mrs Schröder), the Department
of Neuropsychology, University of Regensburg, Regensburg, Germany (Drs Tucha
and Lange and Mr Preier), and PET-Zentrum Mainz, University of Mainz, Mainz,
Germany (Dr Benz).
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