Visualization of the electric field evoked by transcranial electric stimulation during a craniotomy using the finite element method

Ryosuke Tomio, Takenori Akiyama, Tomo Horikoshi, Takayuki Oohira, Kazunari Yoshida

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Background: Transcranial MEP (tMEP) monitoring is more readily performed than cortical MEP (cMEP), however, tMEP is considered as less accurate than cMEP. The craniotomy procedure and changes in CSF levels must affect current spread. These changes can impair the accuracy. The aim of this study was to investigate the influence of skull deformation and cerebrospinal fluid (CSF) decrease on tMEP monitoring during frontotemporal craniotomy. Methods: We used the finite element method to visualize the electric field in the brain, which was generated by transcranial electric stimulation, using realistic 3-dimensional head models developed from T1-weighted images. Surfaces of 5 layers of the head were separated as accurately as possible. We created 3 brain types and 5 craniotomy models. Results: The electric field in the brain radiates out from the cortex just below the electrodes. When the CSF layer is thick, a decrease in CSF volume and depression of CSF surface level during the craniotomy has a major impact on the electric field. When the CSF layer is thin and the distance between the skull and brain is short, the craniotomy has a larger effect on the electric field than the CSF decrease. Comparison with existing method: So far no report in the literature the electric field during intraoperative tMEP using a 3-dimensional realistic head model. Conclusion: Our main finding was that the intensity of the electric field in the brain is most affected by changes in the thickness and volume of the CSF layer.

Original languageEnglish
Article number7343
Pages (from-to)157-167
Number of pages11
JournalJournal of Neuroscience Methods
Volume256
DOIs
Publication statusPublished - 2015 Dec 30

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Craniotomy
Electric Stimulation
Cerebrospinal Fluid
Brain
Head
Skull
Electrodes

Keywords

  • Finite element method
  • Frontotemporal craniotomy
  • Neurosurgery
  • Transcranial electric stimulation
  • Transcranial motor evoked potential

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

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title = "Visualization of the electric field evoked by transcranial electric stimulation during a craniotomy using the finite element method",
abstract = "Background: Transcranial MEP (tMEP) monitoring is more readily performed than cortical MEP (cMEP), however, tMEP is considered as less accurate than cMEP. The craniotomy procedure and changes in CSF levels must affect current spread. These changes can impair the accuracy. The aim of this study was to investigate the influence of skull deformation and cerebrospinal fluid (CSF) decrease on tMEP monitoring during frontotemporal craniotomy. Methods: We used the finite element method to visualize the electric field in the brain, which was generated by transcranial electric stimulation, using realistic 3-dimensional head models developed from T1-weighted images. Surfaces of 5 layers of the head were separated as accurately as possible. We created 3 brain types and 5 craniotomy models. Results: The electric field in the brain radiates out from the cortex just below the electrodes. When the CSF layer is thick, a decrease in CSF volume and depression of CSF surface level during the craniotomy has a major impact on the electric field. When the CSF layer is thin and the distance between the skull and brain is short, the craniotomy has a larger effect on the electric field than the CSF decrease. Comparison with existing method: So far no report in the literature the electric field during intraoperative tMEP using a 3-dimensional realistic head model. Conclusion: Our main finding was that the intensity of the electric field in the brain is most affected by changes in the thickness and volume of the CSF layer.",
keywords = "Finite element method, Frontotemporal craniotomy, Neurosurgery, Transcranial electric stimulation, Transcranial motor evoked potential",
author = "Ryosuke Tomio and Takenori Akiyama and Tomo Horikoshi and Takayuki Oohira and Kazunari Yoshida",
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T1 - Visualization of the electric field evoked by transcranial electric stimulation during a craniotomy using the finite element method

AU - Tomio, Ryosuke

AU - Akiyama, Takenori

AU - Horikoshi, Tomo

AU - Oohira, Takayuki

AU - Yoshida, Kazunari

PY - 2015/12/30

Y1 - 2015/12/30

N2 - Background: Transcranial MEP (tMEP) monitoring is more readily performed than cortical MEP (cMEP), however, tMEP is considered as less accurate than cMEP. The craniotomy procedure and changes in CSF levels must affect current spread. These changes can impair the accuracy. The aim of this study was to investigate the influence of skull deformation and cerebrospinal fluid (CSF) decrease on tMEP monitoring during frontotemporal craniotomy. Methods: We used the finite element method to visualize the electric field in the brain, which was generated by transcranial electric stimulation, using realistic 3-dimensional head models developed from T1-weighted images. Surfaces of 5 layers of the head were separated as accurately as possible. We created 3 brain types and 5 craniotomy models. Results: The electric field in the brain radiates out from the cortex just below the electrodes. When the CSF layer is thick, a decrease in CSF volume and depression of CSF surface level during the craniotomy has a major impact on the electric field. When the CSF layer is thin and the distance between the skull and brain is short, the craniotomy has a larger effect on the electric field than the CSF decrease. Comparison with existing method: So far no report in the literature the electric field during intraoperative tMEP using a 3-dimensional realistic head model. Conclusion: Our main finding was that the intensity of the electric field in the brain is most affected by changes in the thickness and volume of the CSF layer.

AB - Background: Transcranial MEP (tMEP) monitoring is more readily performed than cortical MEP (cMEP), however, tMEP is considered as less accurate than cMEP. The craniotomy procedure and changes in CSF levels must affect current spread. These changes can impair the accuracy. The aim of this study was to investigate the influence of skull deformation and cerebrospinal fluid (CSF) decrease on tMEP monitoring during frontotemporal craniotomy. Methods: We used the finite element method to visualize the electric field in the brain, which was generated by transcranial electric stimulation, using realistic 3-dimensional head models developed from T1-weighted images. Surfaces of 5 layers of the head were separated as accurately as possible. We created 3 brain types and 5 craniotomy models. Results: The electric field in the brain radiates out from the cortex just below the electrodes. When the CSF layer is thick, a decrease in CSF volume and depression of CSF surface level during the craniotomy has a major impact on the electric field. When the CSF layer is thin and the distance between the skull and brain is short, the craniotomy has a larger effect on the electric field than the CSF decrease. Comparison with existing method: So far no report in the literature the electric field during intraoperative tMEP using a 3-dimensional realistic head model. Conclusion: Our main finding was that the intensity of the electric field in the brain is most affected by changes in the thickness and volume of the CSF layer.

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