Structural characteristics of the central nervous system in Friedreich ataxia: an in vivo spinal cord and brain MRI study.

Friedreich ataxia (FRDA) is a spinocerebellar neurodegenerative disorder and the most common autosomal recessive ataxia, mainly caused by GAA-triplet expansions in the FXN gene. This severely debilitating disease usually manifests around adolescence with a slowly progressive phenotype of spinocerebellar signs, areflexia, sensory neuropathy, pyramidal signs and non-neurological features.Neuropathological studies described reductions of dorsal root ganglia, the spinal cord at all levels and dentate nuclei.1 In vivo MRI approaches confirmed spinal cord alterations in FRDA, which were however focused on upper cervical cord areas,2 while quantitative measurements along the entire spinal cord length are lacking. We therefore aimed to investigate the morphometric pattern of the cervical and thoracic spinal cord in FRDA. In order to provide a more comprehensive picture of spinocerebellar-cerebral alterations, we additionally analysed anatomical brain MRI data and investigated the relative contribution of spinal and brain measurements for the prediction of clinical severity in FDRA.Twenty-one patients with genetically confirmed FRDA (35.0±12.2 years; 10 male) were compared with 22 healthy controls (35.5±12.7 years; 11 male; see online supplementary table S-1). Participants were examined using the Scale for the Assessment and Rating of Ataxia (SARA), Inventory of Non-Ataxia Signs (INAS), Activities of Daily Living (ADL) and Spinocerebellar Ataxia Functional Index (SCAFI).### Supplementary data[jnnp-2018-318422-supp1.pdf] T1-weighted spinal cord MRI was acquired on a 3T Prisma scanner (Siemens) using a three-dimensional (3D) gradient-echo sequence (TR=7.8 ms, TE=3 ms, flip angle=16°, 1 mm resolution, field of view: 256 mm (cervical), 320 mm (thoracic)).3 Brain imaging was performed with a magnetisation-prepared rapid …