Brain Topography

, Volume 16, Issue 1, pp 29–38 | Cite as

Measurement of the Conductivity of Skull, Temporarily Removed During Epilepsy Surgery

  • R. Hoekema
  • G.H. Wieneke
  • F.S.S. Leijten
  • C.W.M. van Veelen
  • P.C. van Rijen
  • G.J.M. Huiskamp
  • J. Ansems
  • A.C. van Huffelen

Abstract

The conductivity of the human skull plays an important role in source localization of brain activity, because it is low as compared to other tissues in the head. The value usually taken for the conductivity of skull is questionable. In a carefully chosen procedure, in which sterility, a stable temperature, and relative humidity were guaranteed, we measured the (lumped, homogeneous) conductivity of the skull in five patients undergoing epilepsy surgery, using an extended four-point method. Twenty-eight current configurations were used, in each of which the potential due to an applied current was measured. A finite difference model, incorporating the geometry of the skull and the electrode locations, derived from CT data, was used to mimic the measurements. The conductivity values found were ranging from 32 mS/m to 80 mS/m, which is much higher than the values reported in other studies. Causes for these higher conductivity values are discussed.

Skull conductivity In vivo measurement Finite difference method Source localisation 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Akhtari M., Bryant, H., Mamelak, A., Heller, L., Shih, J., Mandelkern, M., Matlachov, A., Ranken, D., Best, E. and Sutherling, W. Conductivities of three-layer human skull. Brain Topogr., 2000, 13: 29–42.Google Scholar
  2. Akhtari M., Bryant, H., Mamelak, A., Flynn, E., Heller, L., Shih, J., Mandelkern, M., Matlachov, A., Ranken, D., Best, E., DiMauro, M., Lee, R. and Sutherling, W. Conductivities of three-layer live human skull. Brain Topogr., 2002, 14: 151–167.Google Scholar
  3. Alcouffe R., Dendy, J. and Brandt, A. The multigrid solution for problems with strongly discontinuous and anisotropic coefficients. SIAM J. Sci. Comput., 1981. 2: 430–454.Google Scholar
  4. Brandt, A. Multigrid techniques: 1984 guide with applications to fluid dynamics. In: GMD Studien No. 85, Gesellschaft für Mathematik und Datenverarbeitung MBH, Bonn, Germany, 1984.Google Scholar
  5. Goncalves, S., de Munck, J., Heethaar, R., Lopes da Silva, F. and van Dijk, B. The application of electrical impedance tomography to reduce systematic errors in the eeg inverse problem-a simulation study. Physiol. Meas., 2000: 379–393.Google Scholar
  6. Hoekema, R., Venner, K., Struijk, J. and Holsheimer, J. Multigrid solution of the potential field in modeling electrical nerve stimulation. Comput. Biomed. Res., 1998. 31: 348–362.Google Scholar
  7. Huiskamp, G., Vroeijenstijn, M., van Dijk, R., Wieneke, G. and van Huffelen, A.C. The need for correct realistic geometry in the inverse EEG problem. IEEE Trans. Biomed. Engr., 1999, 46: 1281–1287.Google Scholar
  8. Kosterich, J.D., Foster, K.R. and Pollack, S.R. Dielectric properties of fluid saturated bone: The effect of variation in conductivity of immersion fluid. IEEE Trans. Biomed. Engr., 1984, 31: 369–375.Google Scholar
  9. Law, S. Thickness and resistivity variations over the upper surface of the human skull. Brain Topography, 1993, 3: 99–109.Google Scholar
  10. Oostendorp, T., Delbeke, J. and Stegeman, D. The conductivity of the human skull: results of in vivo and in vitro measurements. IEEE Trans. Biomed. Engr., 2000, 47: 1487–1492.Google Scholar
  11. Rush, S. and Driscoll, D.A. Current distribution in the brain from surface electrodes. Anesthesia Analgesia, 1968, 47: 717–723.Google Scholar
  12. Rush, S. and Driscoll, D.A. EEG electrode sensitivity: an application of reciprocity. IEEE Trans. Biomed. Eng., 1969, BME-16: 15–22.Google Scholar
  13. Saha, S. and Williams, P.A. Electric and dielectric properties of wet human cortical bone as a function of frequency. IEEE Trans. Biomed. Eng., 1992. BME:39/12: 1298–1304.Google Scholar
  14. Saha, S., Reddy, G. and Albright, J. Factors affecting the measurement of bone impedance. Med. and Biol. Eng. and Comput., 1984, 22: 123–129.Google Scholar
  15. Viergever, M., Maintz, J., Niessen, W., Noordmans, H., Pluim, J., Stokking, R. and Vincken, K. Registration, segmentation, and visualization of multimodal brain images. Comput. Med. Imaging Graph, 2001, 25: 147–151.Google Scholar

Copyright information

© Human Sciences Press, Inc. 2003

Authors and Affiliations

  • R. Hoekema
    • 1
  • G.H. Wieneke
    • 1
  • F.S.S. Leijten
    • 1
  • C.W.M. van Veelen
    • 2
  • P.C. van Rijen
    • 2
  • G.J.M. Huiskamp
    • 1
  • J. Ansems
    • 3
  • A.C. van Huffelen
    • 1
  1. 1.Dept. of Clinical Neurophysiology,University Medical Center Utrecht,The Netherlands
  2. 2.Dept. of Neurosurgery,University Medical Center Utrecht,The Netherlands
  3. 3.Instrumental service,University Medical Center Utrecht,The Netherlands

Personalised recommendations