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Electrical Conductivities of the Freshly Excised Cerebral Cortex in Epilepsy Surgery Patients; Correlation with Pathology, Seizure Duration, and Diffusion Tensor Imaging

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Summary

The electrical conductivities (σ) of freshly excised neocortex and subcortical white matter were studied in the frequency range of physiological relevance for EEG (5–1005 Hz) in 21 patients (ages 0.67 to 55 years) undergoing epilepsy neurosurgery. Surgical patients were classified as having cortical dysplasia (CD) or non-CD pathologies. Diffusion tensor imaging (DTI) for apparent diffusion coefficient (ADC) and fractional anisotropy (FA) was obtained in 9 patients. Results found that electrical conductivities in freshly excised neocortex vary significantly from patient to patient (σ = 0.0660–0.156 S/m). Cerebral cortex from CD patients had increased conductivities compared with non-CD cases. In addition, longer seizure durations positively correlated with conductivities for CD tissue, while they negatively correlated for non-CD tissue. DTI ADC eigenvalues inversely correlated with electrical conductivity in CD and non-CD tissue. These results in a small initial cohort indicate that electrical conductivity of freshly excised neocortex from epilepsy surgery patients varies as a consequence of clinical variables, such as underlying pathology and seizure duration, and inversely correlates with DTI ADC values. Understanding how disease affects cortical electrical conductivity and ways to non-invasively measure it, perhaps through DTI, could enhance the ability to localize EEG dipoles and other relevant information in the treatment of epilepsy surgery patients.

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Authors and Affiliations

  1. Brain Mapping Division, Neuropsychiatric Institutes, David Geffen School of Medicine, University of California, 660 Charles Young Dr S. Room 215-A, Los Angeles, CA, USA

    M. Akhtari

  2. Department of Physics and Astronomy, The University of New Mexico, Albuquerque, NM, USA

    M. Akhtari & R. Duncan

  3. Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA

    N. Salamon

  4. Division of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA

    I. Fried & G. W. Mathern

  5. The Mental Retardation Research Center, and The Brain Research Institute David Geffen School of Medicine, University of California, Los Angeles, CA, USA

    G. W. Mathern

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  1. M. Akhtari
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  2. N. Salamon
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  3. R. Duncan
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  4. I. Fried
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  5. G. W. Mathern
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Correspondence to M. Akhtari.

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Akhtari, M., Salamon, N., Duncan, R. et al. Electrical Conductivities of the Freshly Excised Cerebral Cortex in Epilepsy Surgery Patients; Correlation with Pathology, Seizure Duration, and Diffusion Tensor Imaging. Brain Topogr 18, 281–290 (2006). https://doi.org/10.1007/s10548-006-0006-x

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