title: Syncope.
abstract: OBJECTIVE
  Syncope is a prevalent syndrome with diverse causes, which have in common a sudden transient failure of the autonomic nervous system to maintain blood pressure against the force of gravity at a level sufficient for cerebral perfusion. Neurally mediated syncope is an episodic phenomenon in which autonomic nervous system function is normal the rest of the time. Although relatively benign, syncope increases the risk for injury from falling and can substantially impair patients' quality of life. Recognition of its various clinical presentations and knowledge of the underlying pathophysiology are essential for accurate diagnosis and successful management.
  
  
  RESULTS
  The most effective forms of treatment remain education of patients, avoidance of triggers, physical counterpressure maneuvers, and hydration or intravascular volume expansion. Pharmacologic interventions may be appropriate for some patients but, in general, have limited evidence of efficacy in preventing syncope. Based on the findings of a recent study, the possibility of pulmonary embolism should be considered in patients hospitalized for syncope, whether or not an alternative etiology for syncope is identified.
  
  
  CONCLUSIONS
  This article focuses on the neurologic diagnosis, differential diagnosis, physiology, and management strategies for syncope, with an emphasis on neurally mediated syncope.
authors.forename: William P
authors.initials: WP
authors.lastname: Cheshire
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013575:Syncope / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000628:therapy