title: Aphasia induced by gliomas growing in the ventrolateral frontal region: assessment with diffusion MR tractography, functional MR imaging and neuropsychology.
abstract: BACKGROUND
  Lesions in the ventrolateral region of the dominant frontal lobe have been historically associated with aphasia. Recent imaging results suggest that frontal language regions extend beyond classically defined Broca's area to include the ventral precentral gyrus (VPCG) and the arcuate fasciculus (AF). Frontal gliomas offer a unique opportunity to identify structures that are essential for speech production. The aim of this prospective study was to investigate the correlation between language deficits and lesion location in patients with gliomas.
  
  
  METHODS
  Nineteen patients with glioma and 10 healthy subjects were evaluated with diffusion tensor imaging magnetic resonance (MR) tractography, functional MR (verb generation task) and the Aachener Aphasie Test. Patients were divided into two groups according to lesion location with respect to the ventral precentral sulcus: (i) anterior (n=8) with glioma growing in the inferior frontal gyrus (IFG) and underlying white matter; (ii) posterior (n=11) with glioma growing in the VPCG and underlying white matter. Virtual dissection of the AF, frontal intralobar tract, uncinate fasciculus (UF) and inferior frontal occipital fasciculus (IFOF) was performed with a deterministic approach.
  
  
  RESULTS
  Seven posterior patients showed aphasia classified as conduction (4), Broca (1), transcortical motor (1) and an isolated deficit of semantic fluency; one anterior patient had transcortical mixed aphasia. All posterior patients had invasion of the VPCG, however only patients with aphasia had also lesion extension to the AF as demonstrated by tractography dissections. All patients with language deficits had high grade glioma. Groups did not differ regarding tumour volume. A functional pars opercularis was identified with functional MR imaging (fMRI) in 17 patients.
  
  
  CONCLUSIONS
  Gliomas growing in the left VPCG are much more likely to cause speech deficits than gliomas infiltrating the IFG, including Broca's area. Lesion extension to the AF connecting frontal to parietal and temporal regions is an important mechanism for the appearance of aphasia.
authors.affiliation: Neuroradiology, Foundation IRCCS Neurological Institute Carlo Besta, Milan, Italy. alberto_bizzi@fastwebnet.it
authors.forename: Alberto
authors.initials: A
authors.lastname: Bizzi
authors.forename: Simone
authors.initials: S
authors.lastname: Nava
authors.forename: Francesca
authors.initials: F
authors.lastname: Ferrè
authors.forename: Gianmarco
authors.initials: G
authors.lastname: Castelli
authors.forename: Domenico
authors.initials: D
authors.lastname: Aquino
authors.forename: Francesca
authors.initials: F
authors.lastname: Ciaraffa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Broggi
authors.forename: Francesco
authors.initials: F
authors.lastname: DiMeco
authors.forename: Sylvie
authors.initials: S
authors.lastname: Piacentini
mesh_terms: D000328:Adult; D001037:Aphasia / Q000209:etiology* / Q000473:pathology* / Q000523:psychology; D001039:Aphasia, Broca / Q000473:pathology / Q000523:psychology; D018886:Aphasia, Conduction / Q000473:pathology / Q000523:psychology; D001929:Brain Edema / Q000473:pathology; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000150:complications* / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D004522:Educational Status; D005260:Female; D005625:Frontal Lobe / Q000473:pathology*; D007839:Functional Laterality / Q000502:physiology; D005910:Glioma / Q000150:complications* / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D009483:Neuropsychological Tests; D011446:Prospective Studies; D013060:Speech / Q000502:physiology; D014705:Verbal Behavior