gms | German Medical Science

61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

Changes of viscoelastic properties of brain tissue in normal pressure hydrocephalus and pathogenetic implications

Meeting Abstract

  • Florian B. Freimann - Neurochirurgische Klinik, Charité – Universität Berlin, Campus Rudolf Virchow, Berlin, Deutschland
  • K. J. Streitberger - Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Deutschland
  • E. Wiener - Abteilung für Neuroradiologie, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Deutschland
  • I. Sack - Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Deutschland
  • Christian Sprung - Neurochirurgische Klinik, Charité – Universität Berlin, Campus Rudolf Virchow, Berlin, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocP1781

DOI: 10.3205/10dgnc252, URN: urn:nbn:de:0183-10dgnc2523

Published: September 16, 2010

© 2010 Freimann et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Objective: While several theories are discussed, our knowledge about the pathogenesis of Normal Pressure Hydrocephalus (NPH) remains inchoate. Magnetic Resonance Elastography (MRE) allows the study of in vivo alterations of viscoelastic properties of brain tissue to explore new aspects of NPH pathophysiology.

Methods: We compared the MRE of 20 patients (mean age 69.1 years, 9 male, 11 female) suffering from idiopathic (n=15) and secondary (n=5) NPH before shunt surgery with an age-matched collective of 25 healthy volunteers (mean age 62.1 years, 10 males, 15 females). Measurements were carried out with multifrequency MRE. Viscoelastic constants related to stiffness (μ) and micro-mechanical connectivity (α) of brain tissue were derived from the dynamics of storage and loss modulus within the experimentally achieved frequency range between 25 Hz and 62.5 Hz. In a second step we correlated the clinical grading of Hakim's triad with MRE-values and finally evaluated the μ- and α-measurements 3 months after shunting.

Results: We found a decrease in the elasticity (loss of stiffness) in NPH brain tissue, expressed by a roughly 20% decreased µ compared to healty volunteers (p<0,001). Alterations in micro-mechanical connectivity of brain tissue could be observed by a decrease of 9% in a (p<0,001).

We did not find a clear correlation between alterations of tissue properties and clinical severity of NPH, but did see a tendency for recovery of the visco-elastic properties parallel to postoperative clinical improvement.

Conclusions: The results show a distinct alteration with a decrease of in elasticity in NPH. We conclude that MRE is capable of measuring the viscoelastic changes in vivo pre- and postoperatively, thus elucidating the pathophysiology of NPH.