title: A Novel Technique for Region and Linguistic Specific nTMS-based DTI Fiber Tracking of Language Pathways in Brain Tumor Patients.
abstract: Navigated transcranial magnetic stimulation (nTMS) has recently been introduced as a non-invasive tool for functional mapping of cortical language areas prior to surgery. It correlates well with intraoperative neurophysiological monitoring (IONM) findings, allowing defining the best surgical strategy to preserve cortical language areas during surgery for language-eloquent tumors. Nevertheless, nTMS allows only for cortical mapping and postoperative language deficits are often caused by injury to subcortical language pathways. Nowadays, the only way to preoperatively visualize language subcortical white matter tracts consists in DTI fiber tracking (DTI-FT). However, standard DTI-FT is based on anatomical landmarks that vary interindividually and can be obscured by the presence of the tumor itself. It has been demonstrated that combining nTMS with DTI-FT allows for a more reliable visualization of the motor pathway in brain tumor patients. Nevertheless, no description about such a combination has been reported for the language network. The aim of the present study is to describe and assess the feasibility and reliability of using cortical seeding areas defined by error type-specific nTMS language mapping (nTMS-positive spots) to perform DTI-FT in patients affected by language-eloquent brain tumors. We describe a novel technique for a nTMS-based DTI-FT to visualize the complex cortico-subcortical connections of the language network. We analyzed quantitative findings, such as fractional anisotropy values and ratios, and the number of visualized connections of nTMS-positive spots with subcortical pathways, and we compared them with results obtained by using the standard DTI-FT technique. We also analyzed the functional concordance between connected cortical nTMS-positive spots and subcortical pathways, and the likelihood of connection for nTMS-positive vs. nTMS-negative cortical spots. We demonstrated, that the nTMS-based approach, especially what we call the "single-spot" strategy, is able to provide a reliable and more detailed reconstruction of the complex cortico-subcortical language network as compared to the standard DTI-FT. We believe this technique represents a beneficial new strategy for customized preoperative planning in patients affected by tumors in presumed language eloquent location, providing anatomo-functional information to plan language-preserving surgery.
authors.affiliation: Department of Clinical and Experimental Medicine, University of MessinaMessina, Italy; Neurosurgical Clinic, Department of Neuroscience, University of MessinaMessina, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Raffa
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin Berlin, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Bährend
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin Berlin, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Schneider
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin Berlin, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Faust
authors.affiliation: Neurosurgical Clinic, Department of Neuroscience, University of Messina Messina, Italy.
authors.forename: Antonino
authors.initials: A
authors.lastname: Germanò
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Vajkoczy
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin BerlinBerlin, Germany; Cluster of Excellence: "Image Knowledge Gestaltung: An Interdisciplinary Laboratory", Humboldt UniversityBerlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Picht
keywords: DTI fiber tracking; brain tumors; eloquent areas; language pathways; nTMS; preoperative planning