ATXN3 and Friedreich ataxia: The observed combined decrease in tibial nerve ρ and T2app in our FRDA patients is similar to previous studies in other neurodegenerative disorders such as SCA3 and HSP [8, 13]; however, while tibial nerve CSA was additionally decreased in SCA3 and HSP, no such change in CSA was observed in our FRDA cohort.