Morphometric correlates of dysarthric deficit in amyotrophic lateral sclerosis

Abstract

Objective: To investigate the volumetric correlates of speech in Amyotrophic Lateral Sclerosis (ALS).Methods: Twenty-three ALS patients had a structural 3D MRI scan, neuropsychological, linguistic and speech assessments. Twenty-three healthy adults of comparable age, education, white-matter hyperintensities and intracranial volumes were also recruited. Between-group differences in grey matter and white matter (WM) were examined to characterise ALS patients accurately. The association between residual speech and volumetric maps was studied in these patients.Results: ALS patients showed a pattern of WM reduction, which was located in peri-cortical motor/premotor fibres bilaterally, and in a large volume extending from the pons/midbrain to the cerebellum. A speech composite score was computed, and this was positively associated with premotor/supplementary-motor WM bilaterally, right cerebellar WM, and the posterior-caudal cerebellar cortex, bilaterally. Conclusion:Variance in residual speech in ALS is associated with variance in premotor WM and cerebellar volumes. Since premotor associations were found in volumes where ALS patients showed WM reduction, this region is believed to be directly involved in speech execution in this group. Since cerebellar associations were instead found in volumes free from shrinkage, this region is interpreted as playing a modulatory role, compensating for the impact of ALS pathology.

Comparison of Gray Matter Atrophy in Behavioral Variant Frontal Temporal Dementia and Amyotrophic Lateral Sclerosis: A Coordinate-Based Meta-Analysis

“…Gray matter volume reduction has been revealed in various brain areas in bvFTD, mainly including frontal and temporolimbic regions (Rosen et al, 2002;Boccardi et al, 2005;Seeley et al, 2008;Hornberger et al, 2011). On the other hand, VBM studies of ALS revealed gray matter volume abnormalities mainly in the motor cortices (Agosta et al, 2007;Mezzapesa et al, 2007;Thivard et al, 2007;Cosottini et al, 2012), though significant brain atrophy was not consistently found (Sage et al, 2007;Minnerop et al, 2009;Luo et al, 2012;De Marco et al, 2015). Reviewing the literature concerning VBM studies of bvFTD (Pan et al, 2012;Schroeter et al, 2014) and ALS (Sheng et al, 2015;Shen et al, 2016) revealed gray matter atrophy in overlapping frontal and temporolimbic regions, suggesting a neurostructural overlap between ALS and bvFTD.…”

Right fronto-parietal white matter disruption contributes to speech impairments in amyotrophic lateral sclerosis

“…In the current study, we used a composite score derived from indices of articulation speed, and phonatory/expiratory endurance to explore, in an unbiased way, its potential pathophysiological substrate in terms of WM abnormalities and, ultimately, brain disconnection. We had previously demonstrated that WM volumes in the motor and premotor subcortical WM, bilaterally, and in the right cerebellum correlate with the severity of speech production deficits in ALS patients [10]. In this study, based on more sensitive measures of WM integrity, we identified the fronto-parietal WM as the core region the microscopic abnormalities of which are associated with speech impairments in patients with ALS (the higher MD/RD, the worse the properties of speech).…”

“…It derives that disruption of such connective tracts may impair the neurological integration of the computational units engaged in speech production. We had previously tested this hypothesis using voxel-based morphometry in a sample of ALS patients without respiratory dysfunction, and a positive association between retained speech production abilities and WM volume of motor/premotor and cerebellar areas was found [10]. The investigation of the sole volumetric features of WM, however, underestimates the presence of subtle microscopic abnormalities that may precede the occurrence of atrophy.…”

Applying the D50 disease progression model to gray and white matter pathology in amyotrophic lateral sclerosis

“…2, Supplementary Table 2A). Former VBM studies have reported circumscribed clusters of decreases in WM density that were often located either next to the motor-cortex, in adjacent areas or within the corticospinal tract (De Marco et al., 2015; Kassubek et al., 2005; Kim et al., 2017a; Tsujimoto et al., 2011). A recent meta-analysis confirmed that the most significantly affected clusters were primarily within the supplementary motor areas, the precentral gyri, and the cerebellum (Chen et al., 2018a).…”