Ryosuke Tomio1, Takenori Akiyama2, Tomo Horikoshi2, Takayuki Ohira2, Kazunari Yoshida2. 1. Departments of Neurosurgery, School of Medicine, Keio University, Tokyo, Japan. Electronic address: tomy0807@hotmail.com. 2. Departments of Neurosurgery, School of Medicine, Keio University, Tokyo, Japan.
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.
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.
Authors: Luca Viganò; Vincenzo Callipo; Marta Lamperti; Marco Rossi; Marco Conti Nibali; Tommaso Sciortino; Lorenzo Gay; Guglielmo Puglisi; Antonella Leonetti; Gabriella Cerri; Lorenzo Bello Journal: Front Oncol Date: 2022-09-29 Impact factor: 5.738
Authors: Andrés Molero-Chamizo; Michael A Nitsche; Carolina Gutiérrez Lérida; Ángeles Salas Sánchez; Raquel Martín Riquel; Rafael Tomás Andújar Barroso; José Ramón Alameda Bailén; Jesús Carlos García Palomeque; Guadalupe Nathzidy Rivera-Urbina Journal: Biology (Basel) Date: 2021-11-25