A diagnostic challenge: spinocerebellar ataxia type 6 presenting with dystonia and parkinsonism

Spinocerebellar ataxias (SCA) are a group of hereditary cerebellar ataxias that are autosomal dominant. They often manifest as an adult-onset progressive neurodegenerative disease with predominantly cerebellar features of gait ataxia, nystagmus and dysarthria. SCA6 is a subtype of SCA which has been historically classified as 'pure cerebellar'. However, many patients may still present with non-cerebellar features. We present a woman in her 70s who was referred to a movement disorder clinic with rigidity, dystonia, upper limb contractures, dysarthria, ocular disturbance and muscle atrophy, with a strong family history of affected individuals. Whole exome sequencing identified 22 CAG repeats in the CACNA1A gene, in keeping with SCA6. A review of the literature identified a broader SCA6 phenotype, which can present with non-cerebellar features, and present a diagnostic challenge.