title: Disruption of structural connectivity along the dorsal and ventral language pathways in patients with nonfluent and semantic variant primary progressive aphasia: a DT MRI study and a literature review.
abstract: Nonfluent (NFV) and semantic (SV) variants of primary progressive aphasia (PPA) are associated with distinct patterns of focal cortical atrophy and underlying pathology. Previous diffusion tensor (DT) MRI studies showed a more ventral white matter (WM) involvement in SV patients and a more widespread frontal involvement in NFV. Aim of this manuscript is twofold. First, we wished to provide a brief state-of-the-art review on WM damage in PPA. Second, we used DT MRI to assess the topography of WM microstructural damage along dorsal and ventral language pathways and corpus callosum in patients with NFV and SV. Our findings show that the two PPA variants share an overlapping pattern of dorsal and ventral pathway abnormalities. In addition to these common abnormalities, variant-specific WM changes were also found, with NFV patients having a more severe damage to the dorsal (fronto-parietal) WM connections within the left superior longitudinal fasciculus/arcuate and SV patients showing a greater left ventral tract involvement (inferior longitudinal and uncinate fasciculi). These findings offer evidence that both dorsal and ventral language networks may contribute to the relatively selective deficits in NFV and SV patients.
authors.affiliation: Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Agosta
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Galantucci
authors.forename: Elisa
authors.initials: E
authors.lastname: Canu
authors.forename: Stefano F
authors.initials: SF
authors.lastname: Cappa
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magnani
authors.forename: Massimo
authors.initials: M
authors.lastname: Franceschi
authors.forename: Andrea
authors.initials: A
authors.lastname: Falini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.forename: Massimo
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000368:Aged; D018888:Aphasia, Primary Progressive / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007802:Language; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology*
keywords: Diffusion tensor MRI; Dorsal stream; Magnetic resonance imaging (MRI); Nonfluent; Primary progressive aphasia; Semantic; Tract-based spatial statistics; Tractography; Ventral stream