Spinocerebellar Ataxia-Type 2 with Dystonia
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia that commonly presents with ataxia, slow saccadic eye movements, dysarthria, and peripheral neuropathy. Extremely slow saccades are common but not pathognomonic. The expanded CAG repeat is SCA2 which encodes polyQ in the abnormal gene product, ataxin-2 (see Chap. 98). Normal alleles are between 15 and 32 repeats in length while expanded alleles are 53–77 repeats in length. Together with SCA6, SCA2 is the form most likely to occur sporadically without a positive family history in prior generations. This is believed to be due to further expansion of a modestly enlarged repeat during transmission from one generation to the next.
KeywordsPeripheral Neuropathy Positive Family History Spinocerebellar Ataxia Cervical Dystonia Normal Allele
SCA2 w. dystonia.mp4 (MP4 14,696KB)
The patient exhibits severe retrocollis, left laterocollis, and elevation of the left shoulder with muscle jerks. Axial dystonia is prominent while walking manifest by opisthotonic posturing which contributes to a tendency to fall backward. (Video contribution from Dr. Priya Jagota, Chulalongkorn Center of Excellence on Parkinson’s Disease and Related Disorders, Thailand).