Teaching Video Neuro Images: Spastic ataxia syndrome

Abstract

A 24-year-old Chilean man with slowly progressive ataxia since age 2 presented with spastic ataxia, hyperreflexia, pes cavus, axonal polyneuropathy, incomplete right-bundle branch block on ECG, and impaired glucose tolerance test, suggesting Friedreich ataxia (figure; video at Neurology.org). However, the combination of hyperreflexia and cerebellar (rather than cervical cord) atrophy with T2-weighted linear hypointensity in the pons on brain MRI suggested autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). Biallelic mutations were found (c.4492C>T p.[R1498X] and c.2388dupA p.[L797Ifs*4]) in the SACS gene (NCBI sequence NM_001278055). ARSACS is the second most common cause of autosomal recessive spastic ataxia syndrome (SACS mutations account for 37% of Friedreich-negative cases) and should be considered in any population with suggestive MRI abnormalities.