Reduced structural connectivity within a prefrontal-motor-subcortical network in amyotrophic lateral sclerosis.

Background: To investigate white matter structural connectivity changes associated with amyotrophic lateral sclerosis (ALS) using network analysis and compare the results with those obtained using standard voxel-based methods, specifically Tract-based Spatial Statistics (TBSS).

Methods: MRI data were acquired from 30 patients with ALS and 30 age-matched healthy controls. For each subject, 85 grey matter regions (network nodes) were identified from high resolution structural MRI, and network connections formed from the white matter tracts generated by diffusion MRI and probabilistic tractography.

Executive deficits, not processing speed relates to abnormalities in distinct prefrontal tracts in amyotrophic lateral sclerosis.

Cognitive impairment in amyotrophic lateral sclerosis is characterized by deficits on tests of executive function; however, the contribution of abnormal processing speed is unknown. Methods are confounded by tasks that depend on motor speed in patients with physical disability. Structural and functional magnetic resonance imaging studies have revealed multi-system cerebral involvement, with evidence of reduced white matter volume and integrity in predominant frontotemporal regions.

Quantitative tractography and tract shape modeling in amyotrophic lateral sclerosis.

Purpose: To investigate brain-wide white matter structural changes associated with amyotrophic lateral sclerosis (ALS) using an automatic single seed point tractography-based segmentation method, probabilistic neighborhood tractography (PNT), which provides quantitative measures of both tract integrity and shape.

Materials And Methods: Diffusion MRI data were acquired from 30 patients with ALS (ALS Functional Rating Scale-Revised score > 20) and 30 matched controls. PNT was used to segment 12 major projection, commissural and association fibers, and assess differences in how the shape of an individual subject's tract compares to that of a predefined reference tract, in addition to providing tract-average mean diffusivity (〈D〉) and fractional anisotropy (FA) data.