title: Role of the left frontal aslant tract in stuttering: a brain stimulation and tractographic study.
abstract: The neural correlates of stuttering are to date incompletely understood. Although the possible involvement of the basal ganglia, the cerebellum and certain parts of the cerebral cortex in this speech disorder has previously been reported, there are still not many studies investigating the role of white matter fibers in stuttering. Axonal stimulation during awake surgery provides a unique opportunity to study the functional role of structural connectivity. Here, our goal was to investigate the white matter tracts implicated in stuttering, by combining direct electrostimulation mapping and postoperative tractography imaging, with a special focus on the left frontal aslant tract. Eight patients with no preoperative stuttering underwent awake surgery for a left frontal low-grade glioma. Intraoperative cortical and axonal electrical mapping was used to interfere in speech processing and subsequently provoke stuttering. We further assessed the relationship between the subcortical sites leading to stuttering and the spatial course of the frontal aslant tract. All patients experienced intraoperative stuttering during axonal electrostimulation. On postsurgical tractographies, the subcortical distribution of stimulated sites matched the topographical position of the left frontal aslant tract. This white matter pathway was preserved during surgery, and no patients had postoperative stuttering. For the first time to our knowledge, by using direct axonal stimulation combined with postoperative tractography, we provide original data supporting a pivotal role of the left frontal aslant tract in stuttering. We propose that this speech disorder could be the result of a disconnection within a large-scale cortico-subcortical circuit subserving speech motor control.
authors.affiliation: Istanbul University Cerrahpasa Medical Faculty, Istanbul, Turkey.
authors.forename: Rahsan
authors.initials: R
authors.lastname: Kemerdere
authors.affiliation: Department of Neuroradiology, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France.|Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors", INSERM U1051, Institute of Neurosciences of Montpellier, Montpellier, France.
authors.forename: Nicolas Menjot
authors.initials: NM
authors.lastname: de Champfleur
authors.affiliation: Department of Neuroradiology, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Deverdun
authors.affiliation: Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, 80 Avenue Augustin Fliche, 34295, Montpellier, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Cochereau
authors.affiliation: Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors", INSERM U1051, Institute of Neurosciences of Montpellier, Montpellier, France.|Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, 80 Avenue Augustin Fliche, 34295, Montpellier, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Moritz-Gasser
authors.affiliation: Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors", INSERM U1051, Institute of Neurosciences of Montpellier, Montpellier, France.|Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, 80 Avenue Augustin Fliche, 34295, Montpellier, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Herbet
authors.affiliation: Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors", INSERM U1051, Institute of Neurosciences of Montpellier, Montpellier, France. h-duffau@chu-montpellier.fr.|Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, 80 Avenue Augustin Fliche, 34295, Montpellier, France. h-duffau@chu-montpellier.fr.
authors.forename: Hugues
authors.initials: H
authors.lastname: Duffau
mesh_terms: D000328:Adult; D056324:Diffusion Tensor Imaging; D004558:Electric Stimulation; D005260:Female; D005500:Follow-Up Studies; D005625:Frontal Lobe / Q000033:anatomy & histology* / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000033:anatomy & histology / Q000503:physiopathology; D013342:Stuttering / Q000503:physiopathology*; D066127:White Matter / Q000033:anatomy & histology* / Q000503:physiopathology*; D055815:Young Adult
keywords: Awake surgery; Connectivity; Frontal aslant tract; Language; Stuttering; Subcortical electrostimulation