Characteristics of Episodic Ataxia Syndrome

Episodic ataxia (EA) is a rare genetic disease characterized by episodes of imbalance, incoordination, and slurring of speech. The underlying cause of EA is only partly understood, and currently there are no established treatments. There is also little information about the link between EA's clinical features and its genetic basis. The purpose of this study is to better characterize EA and disease progression. In turn, this may direct the development of future treatments.

Attacks of ataxia, or the loss of ability to coordinate muscular movement, are often triggered by stress or exertion. EA is likely caused by an inherited genetic mutation; many individuals with EA have abnormalities in the KCNA1 or CACNA1A genes. To date, two known subtypes of EA have been identified, and other types likely exist. Specific characteristics of each EA subtype, however, have not been adequately described. The purpose of this study is to better define the clinical features and genetic basis of the various subtypes of EA and to evaluate disease progression. The study will also establish relevant study endpoints for use in future therapeutic trials.

This multi-center observational study will involve both a cross-sectional data analysis and a prospective longitudinal analysis. Participants will initially attend an outpatient study visit that will last 7 hours. This initial evaluation will include a medical history, a physical examination, neurological testing, and an ataxia assessment. Blood will be collected for genetic testing. Additionally, the following procedures may be conducted: ocular motor test, electromyography/nerve conduction study, electroencephalogram, MRI, and digital videotaping. Follow-up evaluations will occur on a yearly basis for at least 2 years; each will last 4 hours.

Individuals with episodic ataxia

• Episodic Ataxia Syndrome
• Cerebellar Diseases

• Jen J, Kim GW, Baloh RW. Clinical spectrum of episodic ataxia type 2. Neurology. 2004 Jan 13;62(1):17-22.
• Sasaki O, Jen JC, Baloh RW, Kim GW, Isawa M, Usami S. Neurotological findings in a family with episodic ataxia. J Neurol. 2003 Mar;250(3):373-5. No abstract available.
• Denier C, Ducros A, Vahedi K, Joutel A, Thierry P, Ritz A, Castelnovo G, Deonna T, Gerard P, Devoize JL, Gayou A, Perrouty B, Soisson T, Autret A, Warter JM, Vighetto A, Van Bogaert P, Alamowitch S, Roullet E, Tournier-Lasserve E. High prevalence of CACNA1A truncations and broader clinical spectrum in episodic ataxia type 2. Neurology. 1999 Jun 10;52(9):1816-21.

Inclusion Criteria:

• A clinically confirmed diagnosis of episodic ataxia as defined by one of the following three features:

  1. Clear-cut episodes of recurrent, transient ataxia
  2. Mutation confirmed in KCNA1 or CACNA1A
  3. Ataxic features with a first degree relative with episodic ataxia

Exclusion Criteria:

• Any other disorder known to cause episodic ataxia