Diagnosing Premotor Multiple System Atrophy: Natural History and Autonomic Testing in an Autopsy-Confirmed Cohort.

Almost one-third of patients with MSA presented with nonmotor features, which could predate motor symptoms by up to 6 years. Cardiovascular autonomic failure and early urinary catheterization were predictors of poorer outcomes. A normal supine plasma noradrenaline level in patients presenting with PAF phenotype is a possible autonomic biomarker indicating later conversion to MSA.