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

Abstract

BACKGROUND AND PURPOSE:Most DTI studies in ALS have been limited to the assessment of the CST damage. In this study, we used DTI tractography to investigate whether microstructural abnormalities occur in the major motor and extramotor WM tracts in mildly disabled patients with ALS.

Widespread Microstructural White Matter Involvement in Amyotrophic Lateral Sclerosis: A Whole-Brain DTI Study

“…8,9 Significant correlations of diffusion parameters with duration, progression, and severity of the disease also have been reported in some previous studies. 2,[9][10][11][12] Even if the clinical signs of ALS consist of motor impairments, recent evidence suggests that ALS is not an isolated motor neuron disorder 13 and that the variability in the location and extension of FA reduction in patients with ALS is such that relying on a priori ROIs to assess DTI changes may not give a consistent and complete picture of ALS neurodegeneration. Therefore, a novel approach based on whole-brain DTI analysis may result in improved accuracy in detecting subclinical microstructural disease-related WM changes.…”

“…2 DTI is a relatively new method for structural neuroimaging, which allows visualizing the orientation of the fiber tracts and assessing their integrity in the WM by measuring anisotropic water diffusion properties of the brain with MR imaging. 3 DTI has already produced promising results in assessing UMN pathology in patients with ALS, 2,[4][5][6][7][8][9] suggesting that FA, the most sensitive DTI measure, is reduced along the CSTs due to axonal degeneration and loss of fiber integrity, 2,4-6 though AD, MD, and RD changes along the CSTs and other WM structures may also be indicative of degenerative injury. 8,9 Significant correlations of diffusion parameters with duration, progression, and severity of the disease also have been reported in some previous studies.…”

“…3 DTI has already produced promising results in assessing UMN pathology in patients with ALS, 2,[4][5][6][7][8][9] suggesting that FA, the most sensitive DTI measure, is reduced along the CSTs due to axonal degeneration and loss of fiber integrity, 2,4-6 though AD, MD, and RD changes along the CSTs and other WM structures may also be indicative of degenerative injury. 8,9 Significant correlations of diffusion parameters with duration, progression, and severity of the disease also have been reported in some previous studies. 2,[9][10][11][12] Even if the clinical signs of ALS consist of motor impairments, recent evidence suggests that ALS is not an isolated motor neuron disorder 13 and that the variability in the location and extension of FA reduction in patients with ALS is such that relying on a priori ROIs to assess DTI changes may not give a consistent and complete picture of ALS neurodegeneration.…”

“…Most of these studies reported changes of FA and MD mainly in the CSTs, but also in the CC 6,8,15,[17][18][19] and the frontal and temporal lobes. 8,9,15,17,20 Here we used TBSS and VOI DTI analyses to evaluate FA, MD, RD, and AD in whole-brain WM of a heterogeneous group of patients with ALS. These 2 quantitative methods are quite different; TBSS performs statistical analysis on the socalled "FA skeleton" derived from mean FA maps, whereas VOI analysis is based on the Johns Hopkins University WM tractography atlas maps 21,22 obtained from the direct fiber tracking.…”

Neuroimaging in Amyotrophic Lateral Sclerosis

“…Several studies have reported a significant reduction of FA not only in the CST but also in extramotor regions, including the corpus callosum, frontal and parietal WM as well as the hippocampal formation and insula [36,45,48,49]. Using a different methodology, Agosta et al [50] recently reported increased axial diffusivity of the uncinate fasciculus in ALS patients and suggested that uncinate fasciculus involvement may be related to the behavioral symptoms of patients with ALS. The results of these studies support the view that ALS is a multisystem degenerative disease in which abnormalities of extramotor areas play an important role in its pathophysiology.…”