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Individual white matter fractional anisotropy analysis on patients with MRI negative partial epilepsy
  1. Thomas Duning1,
  2. Christoph Kellinghaus1,2,
  3. Siawoosh Mohammadi1,
  4. Hagen Schiffbauer3,
  5. Simon Keller4,
  6. E Bernd Ringelstein1,
  7. Stefan Knecht1,
  8. Michael Deppe1
  1. 1Department of Neurology, University Hospital Muenster, Muenster, Germany
  2. 2Department of Neurology, Klinikum Osnabrueck, Germany
  3. 3Department of Clinical Radiology, University Hospital Muenster, Muenster, Germany
  4. 4The Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, Merseyside, UK
  1. Correspondence to Dr T Duning, Department of Neurology, University Hospital Muenster, Albert-Schweitzer-Str 33, 48149 Muenster, Germany; duningt{at}uni-muenster.de

Abstract

Background Conventional structural MRI fails to identify a cerebral lesion in 25% of patients with cryptogenic partial epilepsy (CPE). Diffusion tensor imaging is an MRI technique sensitive to microstructural abnormalities of cerebral white matter (WM) by quantification of fractional anisotropy (FA). The objectives of the present study were to identify focal FA abnormalities in patients with CPE who were deemed MRI negative during routine presurgical evaluation.

Methods Diffusion tensor imaging at 3 T was performed in 12 patients with CPE and normal conventional MRI and in 67 age matched healthy volunteers. WM integrity was compared between groups on the basis of automated voxel-wise statistics of FA maps using an analysis of covariance. Volumetric measurements from high resolution T1-weighted images were also performed.

Results Significant FA reductions in WM regions encompassing diffuse areas of the brain were observed when all patients as a group were compared with controls. On an individual basis, voxel based analyses revealed widespread symmetrical FA reduction in CPE patients. Furthermore, asymmetrical temporal lobe FA reduction was consistently ipsilateral to the electroclinical focus. No significant correlations were found between FA alterations and clinical data. There were no differences in brain volumes of CPE patients compared with controls.

Conclusion Despite normal conventional MRI, WM integrity abnormalities in CPE patients extend far beyond the epileptogenic zone. Given that unilateral temporal lobe FA abnormalities were consistently observed ipsilateral to the seizure focus, analysis of temporal FA may provide an informative in vivo investigation into the localisation of the epileptogenic zone in MRI negative patients.

  • Epilepsy
  • MRI
  • cryptogenic partial epilepsy
  • diffusion tensor imaging
  • fractional anisotropy
  • white matter

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Footnotes

  • Funding This work was supported by grants from the Neuromedical Foundation Muenster, the German Research Association Sonderforschungsbereich (SFB)/TR3 and by the BMBF-Research Consortium (Bundesministerium für Bildung und Forschung , BMBF 016W0520).

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the ethics committee of the Westfälischen Wilhelms-University of Muenster, Münster, Germany.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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