Orthostatic hypotension — a sudden drop in blood pressure when standing up, which can cause dizziness, falls and injury. Symptoms like orthostatic hypotension fall into the category of autonomic dysfunction that affects many people living with Parkinson’s disease. Other symptoms are chronic fatigue, orthostatic dizziness, weakness, sleep disturbance, syncope or near syncope, headache, and loss of appetite.
patients into two groups: group I (32 patients) had either a recovery time for mean arterial pressure of >25 s or a recovery time of >20 s with a 64% or greater decrease in mean arterial pressure at the initial decrease; group II (14 patients) had a prolonged reduction in systolic arterial pressure of >17% during the later stage of standing (3–7 min) in addition to the criteria for group I. INOH was characterized by a marked reduction in blood pressure at the initial decrease (mean, −55/−27 mm Hg systolic/diastolic). Delayed recovery time of >60 s was found in 23 of 44 patients and orthostatic tachycardia (>35 beats per minute) in 21 of 44. Plasma noradrenaline responses were significantly lower in group I and II than in controls at 1 min of standing and were lower in group II at 6 min of standing. These results suggest that mechanisms responsible for INOH may depend on insufficient sympathetic activation during standing