BACKGROUND AND PURPOSE: Spinocerebellar ataxia type 7 is an autosomal dominant neurodegenerative disease caused by a cytosine-adenine-guanine (CAG) repeat expansion. Clinically, spinocerebellar ataxia type 7 is characterized by progressive cerebellar ataxia, pyramidal signs, and macular degeneration. In vivo MR imaging studies have shown extensive gray matter degeneration in the cerebellum and, to a lesser extent, in a range of cortical cerebral areas. The purpose of this study was to evaluate the impact of the disease in the spinal cord and its relationship with the patient's impairment.
MATERIALS AND METHODS: Using a semiautomated procedure applied to MR imaging data, we analyzed spinal cord area and eccentricity in a cohort of 48 patients with spinocerebellar ataxia type 7 and compared them with matched healthy controls. The motor impairment in the patient group was evaluated using the Scale for Assessment and Rating of Ataxia.
RESULTS: Our analysis showed a significantly smaller cord area ( t = 9.04, P < .001, d = 1.31) and greater eccentricity ( t = -2.25, P =. 02, d = 0.32) in the patient group. Similarly, smaller cord area was significantly correlated with a greater Scale for Assessment and Rating of Ataxia score ( r = -0.44, P = .001). A multiple regression model showed that the spinal cord area was strongly associated with longer CAG repetition expansions ( P = .002) and greater disease duration ( P = .020).
CONCLUSIONS: Our findings indicate that cervical spinal cord changes are progressive and clinically relevant features of spinocerebellar ataxia type 7, and future investigation of these measures as candidate biomarkers is warranted.
Bibliographical noteFunding Information:
Received February 5, 2021; accepted after revision April 12. From the Faculty of Computer Science (C.R.H.-C.), Dalhousie University, Halifax, Nova Scotia, Canada; Physiology Department, Faculty of Medicine (R.D., J.F.-R.), Universidad Nacional Autónoma de México, Cuidad de Mexico, Mexico; Department of Neurology and Neuroimaging Laboratory (T.J.R.R.), School of Medical Sciences, University of Campinas, São Paulo, Brazil; Institut national de la santé et de la recherche médicale, Centre national de la recherche scientifique, Sorbonne Universités, Paris Brain Institute, Paris, France; Department of Neuroscience (I.H.), Central Clinical School, Monash University, Melbourne, Australia; and Department of Genetics (F.M.), Assistance Publique–Hôpitaux de Paris, Pitié-Salpêtrière University Hospital, Paris, France. This work was supported by Consejo Nacional de Ciencia y Tecnología grant No. A1-S-10669 and Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica - Universidad Nacional Autónoma de México grant No. IN220019 to Juan Fernandez-Ruiz. Please address correspondence to Juan Fernandez-Ruiz, MD, PhD, Departmento de Fisiologia, Facultad de Medicina, Universidad Nacional Autónoma de México, Av. Universidad 3000, A.P. 70-250, C.P. 04510, CDMX, Mexico; e-mail: email@example.com Indicates article with online supplemental data. http://dx.doi.org/10.3174/ajnr.A7202
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