title: Abnormal corticospinal tract function and motor cortex excitability in non-ataxic SCA2 mutation carriers: A TMS study.
abstract: To evaluate if the corticospinal tract is affected in the prodromal stage of spinocerebellar ataxia type 2 (SCA2), prior to development of the cerebellar syndrome.
  
  
  
  A cross-sectional study was conducted in 37 non-ataxic SCA2 mutation carriers and in age- and sex-matched healthy controls. All subjects underwent clinical assessment and transcranial magnetic stimulation to determine corticospinal tract integrity to the right abductor pollicis brevis and tibialis anterior muscles.
  
  
  
  Non-ataxic SCA2 mutation carriers showed significantly higher resting and active motor thresholds for both muscles, and prolonged cortical silent periods and central motor conduction times (CMCT), compared to controls. CMCT to the tibialis anterior correlated directly with CAG repeat size, and inversely with predicted time to ataxia onset.
  
  
  
  Findings provide novel electrophysiological evidence for affection of the corticospinal tract and motor cortex in prodromal SCA2. Slowed conduction in the corticospinal tract to the lower limbs reflects polyglutamine neurotoxicity, and predicts time to ataxia onset.
  
  
  
  Identification of corticospinal tract damage and decreases motor cortical excitability in the prodromal stage of SCA2 allows early disease monitoring. This will become important as soon as effective neuroprotective treatment will be available.
authors.affiliation: Dept. Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Libertad Street 26, Holguin 80100, Cuba. Electronic address: luis.velazquez@infomed.sld.cu.
authors.forename: Luis
authors.initials: L
authors.lastname: Velázquez-Pérez
authors.affiliation: Dept. Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Libertad Street 26, Holguin 80100, Cuba.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rodríguez-Labrada
authors.affiliation: Dept. Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Libertad Street 26, Holguin 80100, Cuba.
authors.forename: Reidenis
authors.initials: R
authors.lastname: Torres-Vega
authors.affiliation: Dept. Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Libertad Street 26, Holguin 80100, Cuba.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Medrano Montero
authors.affiliation: Dept. Molecular Neurobiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Libertad Street 26, Holguin 80100, Cuba.
authors.forename: Yaimeé
authors.initials: Y
authors.lastname: Vázquez-Mojena
authors.affiliation: Exp. Neurology, Building 89, Goethe University Medical School, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Auburger
authors.affiliation: Dept. Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University Tübingen, Hoppe-Seyler-Straße 3, 72076 Tübingen, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ziemann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000067698:Ataxin-2 / Q000235:genetics*; D003430:Cross-Sectional Studies; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009154:Mutation; D009431:Neural Conduction / Q000502:physiology; D011712:Pyramidal Tracts / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
chemical_list: C000593752:ATXN2 protein, human; D000067698:Ataxin-2
keywords: Corticospinal tract; Motor cortex; Motor evoked potentials; Prodromal disease stage; Spinocerebellar ataxia type 2; Transcranial magnetic stimulation