Introduction

Syncope is a common problem that many clinicians may encounter in various outpatient settings. Neurally mediated syncopal syndrome includes carotid sinus syndrome, situational syncope, and neurocardiogenic syncope (also known as vasovagal syncope), which is the most common cause of syncope in both children and adults, accounting for 50-66% of unexplained syncope.1 2 The distinction between neurocardiogenic syncope and other causes of fainting is essential, as the prognosis and treatment are different.

Sources and selection criteria

We selected articles from the PubMed database by using the search words “syncope” and “neurocardiogenic syncope.” Inclusion criteria were articles published in English, in peer reviewed journals, between 1980 and 2004. Exclusion criteria were articles not published in English, case reports, and articles not published in peer reviewed journals. We incorporated guidelines from the American College of Cardiology, European Society of Cardiology, and American Heart Association, along with a summary of clinical trials. We selected 31 references for this review.

Definition and incidence

Syncope is defined as a transient loss of consciousness, with loss of posture (that is, falling). Commonly described as “fainting,” “passing out,” or “blackout,” syncope accounts for 3% of visits to emergency departments and 6% of all admissions to hospital.1 3 It occurs relatively often in all age groups, ranging from 15% in children aged under 18 years to 23% in elderly patients aged over 70.4 The prevalence and incidence of syncope increase with advancing age,5 with a 30% recurrence rate.3

Neurocardiogenic syncope, with a mean prevalence of 22% in the general population,2 is defined as a syndrome in which “triggering of a neural reflex results in a usually self-limited episode of systemic hypotension characterized by both bradycardia (asystole or relative bradycardia) and peripheral vasodilation.”6

Causes of syncope

Syncope is a symptom, not a disease, and can be classified according to the underlying cause: neurological, …