Orthostatic hypotension Acute Primary Acute pandysautonomia Acute Secondary Dehydration Bed Rest Drugs Chronic Primary Pure autonomic failure Multiple system atrophy Chronic Secondary Diabetes Amyloid Paraneoplastic syndromes Drugs Neurally Mediated (Reflex) Carotid sinus hypersensitivity Glossopharyngeal neuralgia and syncope Visceral syncope (micturition,

Syncope is a sudden and transient loss of consciousness and postural tone, usually described as “fainting” or “passing out”. It is a common problem, accounting for 3% of emergency room visits. A history of an isolated episode of syncope will be found in as many as 25% of healthy young adults, especially in settings that precipitate fear, disgust or anxiety, and if not repeated does not warrant further work-up. Repeated episodes, however, may be caused by a wide variety of medical problems, and require diagnosis and treatment. It is important to distinguish syncope from “dizziness”, which generally refers to an alteration in balance, vision, or perception of the environment, without the loss of consciousness. Causes of syncope can be differentiated into two major classifications, cardiac and noncardiac. Examples of cardiac syncope are heart rhythm disturbances or abnormalities in the structure of the heart. The list below presents a useful classification of noncardiac syncope: