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Eloquent brain regions1/20/2024 The intracranial stimulation points are then saved for later analysis. As reported earlier, the stimulating coil induces an electric field within the brain, which is represented by the software as a 3D reconstruction. Briefly, the 3D T1-weighted MRI of each participant was used as an anatomical reference and registered to the participant's brain to visualize the exact brain area receiving rTMS pulses by a stereotactic camera to track coil position. Language mapping was performed with the Nexstim eXimia NBS system 4.3 with the NexSpeech® module (Nexstim Oy, Helsinki, Finland) as documented earlier. The following experimental setup was applied to all participants without differences between the groups. Thus, this study was designed to find evidence for the extent of change in language lateralization for every single gyri via a virtual lesion model using rTMS of both hemispheres. īecause a change in language lateralization would increase surgical options for patients with left-sided perisylvian tumors, it would represent a new approach in surgical neurooncology. Moreover, we showed the superiority of rTMS language mapping compared to fMRI in a glioma patient in terms of language lateralization. In a recently performed study, our group showed a high sensitivity of preoperative language mapping by rTMS compared to intraoperative DCS during awake surgery when the human cortex was divided by the sections according to the cortical parcellation system. However, in these previous works, the extent of language lateralization was not investigated with a high spatial resolution concerning the exact location of the gyri involved in changed lateralization of language function. For brain-tumor patients, the right inferior frontal gyrus (IFG) was also shown to be involved in language production in a previous study using non-navigated TMS combined with an object-naming task. These reports used a variety of methods, including neuropsychological assessment, non-navigated TMS, and mainly fMRI, which is frequently impaired by intracerebral tumors and ischemic lesions. The right hemisphere was shown to participate in language function not only in healthy participants, ,, , but also in patients after left-hemispheric stroke, or brain tumors, ,,. It has thus been shown that rTMS during an object-naming task allows us to map the cortex for language eloquent regions. Moreover, by combining repetitive TMS with a navigation system, we can even specifically define cortical regions, which are vulnerable to repetitive nTMS (rTMS) and therefore considered language-eloquent. By combining it with an object-naming task, this repetitive TMS has been repeatedly used for disturbing language function and determination of language lateralization in the past. But by applying pulse trains, we can also depolarize neurons and therefore cause a “virtual lesion” for the 1–4 seconds of stimulation. By single pulse stimulation, it can elicit muscular evoked potentials within the motor cortex. This method allows the transcranial non-invasive magnetic induction of an electric field within the cortex. Navigated transcranial magnetic stimulation (nTMS) is increasingly used for preoperative mapping of the primary motor cortex, and a good correlation of preoperative nTMS and intraoperative DCS motor maps has been repeatedly reported. Although intraoperative mapping is highly reliable, it does not allow for the examination of language distribution in the healthy brain. Current knowledge is mainly based on functional MRI (fMRI) studies, , and on intraoperative language mapping by bipolar direct cortical stimulation (DCS) during awake surgery for the left hemisphere, , and, but also for the right hemisphere. The cortical distribution and variability of human language representation has been widely examined. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. Moreover, SK received a grant of the “Stiftung Neurochirurgische Forschung” of the German Neurosurgical Society (DGNC). This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: The study was mostly financed by institutional grants from the Department of Neurosurgery and the Section of Neuroradiology, TU Munich, and the authors declare that they have no conflict of interest affecting this study. Received: JAccepted: AugPublished: September 17, 2013Ĭopyright: © 2013 Krieg et al. PLoS ONE 8(9):Įditor: Jan Kassubek, University of Ulm, Germany (2013) Functional Language Shift to the Right Hemisphere in Patients with Language-Eloquent Brain Tumors. Citation: Krieg SM, Sollmann N, Hauck T, Ille S, Foerschler A, Meyer B, et al.
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