<unk> , also known as postural<unk> , is a medical condition wherein a person's blood pressure drops when standing up or sitting down. Primary<unk>  hypertension is also often referred to as neurogenic<unk> . The drop in blood pressure may be sudden (vasovagal<unk> , within 3 minutes (classic<unk>  or gradual (delayed<unk> . It is defined as a fall in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg when a person assumes a standing position. It occurs predominantly by delayed (or absent) constriction of the lower body blood vessels, which is normally required to maintain adequate blood pressure when changing the position to standing. As a result, blood pools in the blood vessels of the legs for a longer period, and less is returned to the heart, thereby leading to a reduced cardiac output and inadequate blood flow to the brain. Very mild occasional<unk>  is common and can occur briefly in anyone, although it is prevalent in particular among the elderly and those with known low blood pressure. Severe drops in blood pressure can lead to fainting, with a possibility of injury. Moderate drops in blood pressure can cause confusion/inattention, delirium, and episodes of ataxia. Chronic<unk>  is associated with cerebral hypoperfusion that may accelerate the pathophysiology of dementia. Whether it is a causative factor in dementia is unclear. The numerous possible causes for<unk>  include certain medications (e.g. alpha blockers), autonomic neuropathy, decreased blood volume, multiple system atrophy, and age-related blood-vessel stiffness. Apart from addressing the underlying cause,<unk>  may be treated with a recommendation to increase salt and water intake (to increase the blood volume), wearing compression stockings, and sometimes medication (fludrocortisone, midodrine, or others). Salt loading (dramatic increases in salt intake) must be supervised by a doctor, as this can cause severe neurological problems if done too aggressively.
Orthostatic hypotension
Reflex syncope  Reflex syncope  1
Carotidynia
Reflex bradycardia
Oscillopsia
Cardiovascular drift
Cyclospasm
Hyperpathia