Dilemma of multiple system atrophy and spinocerebellar ataxias

Multiple system atrophy (MSA) and spinocerebellar ataxias (SCAs) are both progressive neurodegenerative disorders, which can manifest cerebellar dysfunctions and parkinsonism-related symptoms, although the former is sporadic and the latter is autosomal dominant disease. Routinely, diagnosis is primarily based on clinical information-thorough history and physical examination should be included. Provided family history obtained, distinguishing SCAs from MSA is easy. However, how can we diagnose MSA or SCAs, in case of insufficient and unconvinced clinical symptoms or family history? Especially, familial MSA cases had been reported recently. We may drop into a dilemma resulting from analogous manifestations between MSA and SCAs. Herein, we aim to give a comprehensive introduction of MSA and SCAs, mainly in phenotype and genotype, and then address the connection and difference between them. Recently, some studies had been put forward to figure out the overlapped features between MSA and SCAs. Through this review, we want to discuss the possibility of misdiagnosis between MSA and SCAs.