Paroxysmal Ataxia: A Characteristic Feature of FGF14 Repeat Expansion (SCA27B).

Objectives: Paroxysmal ataxia is typically characterized by early-onset attacks of cerebellar ataxia. Late-onset cerebellar ataxia (LOCA) comprises a group of neurodegenerative disorders mainly characterized by adult-onset progressive cerebellar ataxia. A deep intronic expansion of a GAA triplet in the gene encoding fibroblast growth factor 14 has recently been identified as a frequent cause of LOCA.

Methods: We describe a patient with paroxysmal ataxia/dysarthria due to a repeat expansion and 3 affected family members.

Results: The 4 patients had paroxysmal ataxia/dysarthria occurring between 45 and 50 years as the initial manifestation of a repeat expansion. The index case was investigated in detail. We have provided a video showing one of her paroxysmal episodes that could be triggered by alcohol, coffee, exertion, emotion, or cigarette smoking. Brain MRI revealed mild cerebellar atrophy, and oculography showed a subclinical downbeat nystagmus. Treatment with acetazolamide resulted in remarkable improvement.

Discussion: Paroxysmal dysarthria/ataxia should prompt the clinician to test for repeat expansion/SCA27B, especially when the paroxysmal attacks are associated with late-onset cerebellar ataxia and/or a family history consistent with a dominant disorder.