Early distinction of Parkinsonian-variant multiple system atrophy from Parkinson’s disease

Distinguishing the Parkinson variant of MSA (MSA-P) from Parkinson’s disease (PD) is often difficult at disease onset. This is a major drawback for counseling of patients and timely enrollment into disease-modifying clinical trials. Clinicopathological studies consistently report that postural instability and autonomic failure emerge earlier in MSA-P than in PD, but it remains to be determined how this information can be integrated into the diagnostic work-up of patients with early parkinsonism. Here, we aimed at (1) quantifying the diagnostic yield of early-onset postural instability as well as cardiovascular and urological autonomic failure in differentiating MSA-P from PD and (2) merging early MSA-P distinctive features into a MSA-P diagnostic probability score