Cerebellar Ataxia Type 1

  • Roongroj Bhidayasiri
  • Daniel Tarsy
Part of the Current Clinical Neurology book series (CCNEU)


Spinocerebellar ataxia-type 1 (SCA1) was the first dominantly inherited ataxia for which the locus and gene defect were identified. SCA1 is caused by polyQ-encoding CAG repeat expansions resulting in production of the abnormal protein, Ataxin-1. Similar to other polyQ diseases, SCA1 shows considerable phenotypic variability and anticipation that reflects differences in repeat size among affected individuals. Most patients present in the fourth decade with a pancerebellar syndrome including ataxia of gait, stance, and limbs and dysarthria. Oculomotor abnormalities include gaze-evoked nystagmus, saccadic hypermetria, breakdown of smooth pursuit eye movements, and reduced opticokinetic nystagmus. In most patients, there are additional noncerebellar signs. Spasticity with extensor plantar responses and hyperreflexia occur in more than 50% of SCA1 patients.


Cerebellar Ataxia Vocal Cord Paralysis SCA1 Patient Repeat Size Important Clinical Problem 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Supplementary material

The patient is being examined for cerebellar signs. He is able to walk independently but unsteadily. His gait is slightly wide-based. He performs tandem gait with difficulty with a tendency to veer to the right. Tandem stance and heel-knee-shin testing are normal. Speech is slow and dysarthric with a monotonous low-pitch tone. (Video contribution from Dr. Susan Perlman, Department of Neurology at David Geffen School of Medicine at UCLA.)

Exam of patient w SCA.mp4(MP4 35,988KB)


  1. 1.
    Zoghbi HY, Orr HT. Pathogenic mechanisms of a polyglutamine-mediated neurodegenerative disease, spinocerebellar ataxia type 1. J Biol Chem. 2009;284(12):7425–9.PubMedCentralPubMedCrossRefGoogle Scholar
  2. 2.
    Sasaki H, Fukazawa T, Yanagihara T, et al. Clinical features and natural history of spinocerebellar ataxia type 1. Acta Neurol Scand. 1996;93:64–71.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Roongroj Bhidayasiri
    • 1
    • 2
  • Daniel Tarsy
    • 3
  1. 1.Chulalongkorn Center of Excellence on Parkinson’s Disease and Related DisordersChulalongkorn University HospitalBangkokThailand
  2. 2.Department of NeurologyDavid Geffen School of Medicine at UCLALos AngelesUSA
  3. 3.Department of NeurologyHarvard Medical School Beth Israel Deaconess Medical CenterBostonUSA

Personalised recommendations