Reflex Syncope

Abstract Syncope is a transient, brief and self-limited loss of consciousness due to global cerebral hypoperfusion. This specific pathophysiology sets syncope apart from other conditions causing transient loss of consciousness (TLOC) including generalised epileptic seizures, functional TLOC (psychogenic nonepileptic seizures and psychogenic pseudosyncope, mimicking epileptic seizures and syncope respectively), and less common disorders causing TLOC. There are three groups of syncope causes: reflex syncope (synonymous with neurally mediated syncope), syncope due to orthostatic hypotension and cardiac syncope (arrhythmic or associated with structural cardiac disease). Reflex syncope is by far the most common form of TLOC, affecting up to 40% of the population. Important diagnostic clues include the circumstances of the attack (e.g. fear, pain, standing, cessation of exercise), prodromal features (e.g. sweating, nausea, pallor, blurred vision), the prevention of TLOC by sitting or lying down and the prompt and complete recovery of consciousness. Taking a thorough step-by-step history of as many attacks as possible is the cornerstone of the diagnosis of reflex syncope and means that additional testing can be avoided in many patients.