Cardiovascular autonomic dysfunction in MSA and Parkinson's disease: similarities and differences.

In Parkinsons disease and multiple system atrophy (MSA), cardiovascular dysfunction may occur for a variety of reasons and may manifest itself through inappropriate changes and/or levels in blood pressure, heart rate and/or regional vascular perfusion in a range of situations. The early occurrence of orthostatic hypotension often leads to consideration of MSA, especially in the presence of other features of autonomic failure. Orthostatic hypotension, however, is increasingly recognised in PD, and especially with increasing age, severity of disease and as a result of drug therapy, sometimes for associated disorders. Investigation of cardiovascular autonomic dysfunction in Parkinsonism is therefore important for a variety of reasons, that include determining the precise diagnosis and in predicting prognosis. In Parkinsonian disorders, understanding the pathophysiological basis of the cardiovascular autonomic dysfunction aids targeting of therapy, improves management strategies and provides benefit for such patients.