Evidence of White Matter Changes on Diffusion Tensor Imaging in Frontotemporal Dementia

Abstract

Background: Two major clinical variants of frontotemporal dementia (FTD) have been described: frontal variant (fvFTD) and temporal variant (tvFTD).Objective: To analyze white matter (WM) and gray matter (GM) tissue organization in patients with fvFTD and tvFTD by means of diffusion tensor imaging and voxelbased morphometry, and the correlations with neuropsychological and behavioral variables. Design and Setting: Frontotemporal dementia clinicbased cohort and structural magnetic resonance imaging acquisition for voxel-based morphometry and diffusion tensor imaging measurements. Abnormalities were detected by a comparison with healthy control subjects. These variables were also correlated with clinical scores. Patients: Thirty-six patients (28 with fvFTD and 8 with tvFTD) in early disease stage and 23 healthy controls who underwent standardized clinical and neuropsychological evaluation and magnetic resonance imaging. Interventions: Diffusion tensor imaging and voxelbased morphometry. Main Outcome Measures: Neuroimaging analyses resulted in localized GM atrophy and reductions of white matter densities; the latter correlated with behavioral scores.Results: Voxel-based morphometry analysis showed separate patterns of GM atrophy in the 2 groups. Diffusion tensor imaging showed different WM reduction patterns in patients with fvFTD and tvFTD. The fvFTD group showed a selective WM reduction in the superior longitudinal fasciculus, interconnecting the frontal and occipital and the temporal and parietal regions. Conversely, patients with tvFTD were characterized by WM reductions in the inferior longitudinal fasciculus, which affected the connections between anterior temporal and frontal regions. The WM reductions in fvFTD paralleled both behavioral disturbances measured by Frontal Behavioral Inventory and neuropsychological deficits affecting frontal functions. Conclusions:The fvFTD and tvFTD variants are associated not only with selective local GM reductions but also with significant WM damage in early disease phase. The different WM patterns contribute to the different clinical syndromes in FTD and could be responsible for the further progression of atrophy in the later disease stages.

Structural connectivity in a single case of progressive prosopagnosia: The role of the right inferior longitudinal fasciculus

“…Such data suggested that DTI measures can contribute to characterize patients with different variants of FTD and their clinical symptoms (Borroni et al, 2007).…”

“…To our knowledge, there are no studies in literature that explore brain connectivity in PP or in rtFTD, whereas tractography studies in temporal variants of FTD showed bilateral reductions in ILF and IFOF, thus suggesting disrupted connectivity between the posterior occipital pole and the anterior temporal lobe (ILF), and between the inferolateral and dorsolateral frontal cortices and both the temporal and occipital cortices (IFOF; Borroni et al, 2007). Such data suggested that DTI measures can contribute to characterize patients with different variants of FTD and their clinical symptoms (Borroni et al, 2007).…”

Assessment of White Matter Tract Damage in Patients with Amyotrophic Lateral Sclerosis: A Diffusion Tensor MR Imaging Tractography Study: Fig 1.

“…This hypothesis is also supported by recent findings of a similarly damaged uncinate fasciculus in patients with behavioral FTD 54,55 and semantic dementia 54,56 and by the association between medial and ventral frontal WM damage and behavioral symptoms in patients with behavioral FTD. 57 Longitudinal studies are now warranted to assess whether the extent and severity of the MR imagingϪ detectable extramotor damage is predictive of subsequent development of cognitive impairment in patients with ALS. We should mention some limitations of our study: first, the relatively small sample size, which was nevertheless comparable with previous reports.…”

White matter imaging contributes to the multimodal diagnosis of frontotemporal lobar degeneration

“…several tracts relative to healthy seniors, 12,13 although the distribution of disease may vary across clinical phenotypes. 9,10 In a comparative study of CSF-defined groups, reduced fractional anisotropy (FA) in corpus callosum and inferior frontal-occipital fasciculus was found in FTLD relative to AD.…”