Twenty-four-hour ambulatory blood pressure and heart rate profiles in diagnosing orthostatic hypotension in Parkinson's disease and multiple system atrophy.

Parkinson's disease with autonomic failure and MSA patients had similar circadian BP patterns suggesting that autonomic dysfunction influences abnormal BP circadian patterns similarly in these disorders. The higher sensitivity and specificity in detecting OH using a systolic BP fall of >20 mmHg compared to a diastolic BP fall of >10 mmHg during the standing test supports its usefulness to assess autonomic function in MSA and PD.