title: Ataxia Severity Correlates with White Matter Degeneration in Spinocerebellar Ataxia Type 7.
abstract: OBJECTIVE
  There is a scarcity of information on the effect of white matter degeneration in patients with spinocerebellar ataxia type 7. Therefore, we investigated the WM integrity in a large group of patients with spinocerebellar ataxia type 7 by using Tract-Based Spatial Statistics.
  
  
  METHODS
  Thirty-three patients with a molecular diagnosis of spinocerebellar ataxia type 7 and their age- and sex-matched healthy controls participated in this study. The patients' ataxia severity was evaluated with the Scale for the Assessment and Rating of Ataxia. Voxelwise analyses of diffusion metrics, including fractional anisotropy and mean diffusivity, were performed with Tract-Based Spatial Statistics. The correlation between WM abnormalities and ataxia severity was then calculated.
  
  
  RESULTS
  Tract-Based Spatial Statistics analysis revealed WM abnormalities in the cerebellum and the cerebellar peduncles, as well as in other major cortical and subcortical pathways. Further analysis between the Scale for the Assessment and Rating of Ataxia score and WM mean diffusivity showed significant associations only in key areas related to motor control and visuospatial processing, including the cerebellar WM, the middle occipital WM, the superior cerebellar peduncle, and bilateral anterior thalamic radiation. No significant associations between fractional anisotropy and the Scale for the Assessment and Rating of Ataxia were found.
  
  
  CONCLUSIONS
  These results suggest a significant contribution of local cerebellar and cerebellar-midbrain connections to ataxic impairment in spinocerebellar ataxia type 7. The results also suggest an involvement of cortical WM abnormalities including tracts within the occipital and frontal cortices. These findings contribute to a more comprehensive view of the clinical impact of the white matter degeneration in spinocerebellar ataxia type 7.
authors: From the Consejo Nacional de Ciencia y Tecnologia-Instituto de Neuroetologia (C.R.H.-C.), Universidad Veracruzana, Veracruz, Mexico.
authors: C R
authors: http://orcid.org/0000-0003-1208-5577
authors: CR
authors: Hernandez-Castillo
authors: Departamento de Fisiologia (I.V.-P., J.F.-R.), Facultad de Medicina.
authors: I
authors: http://orcid.org/0000-0002-2067-864X
authors: I
authors: Vaca-Palomares
authors: Instituto de Neurobiologia (F.B.), Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
authors: F
authors: http://orcid.org/0000-0002-5699-4222
authors: F
authors: Barrios
authors: Departamento de Neurogenética y Biologıa Molecular (L.M.).
authors: L
authors: http://orcid.org/0000-0001-5307-1804
authors: L
authors: Martinez
authors: Laboratorio de Investigacion Clinica (M.-C.B.), Instituto Nacional de Neurología y Neurocirugía, "Manuel Velasco Suárez," Mexico City, México.
authors: M-C
authors: http://orcid.org/0000-0002-4886-3011
authors: MC
authors: Boll
authors: Departamento de Fisiologia (I.V.-P., J.F.-R.), Facultad de Medicina jfr@unam.mx.
authors: J
authors: http://orcid.org/0000-0002-4038-0904
authors: J
authors: Fernandez-Ruiz