What is Vasovagal Syncope?

Vasovagal syncope refers to a syndrome characterized by transient loss of consciousness caused by vagally mediated reflexes triggered by various stimuli. These reflexes lead to vasodilation of visceral and muscular small vessels, bradycardia, sudden peripheral vasodilation, and reduced venous return to the heart—resulting in abrupt slowing of the heart rate, peripheral vasodilation, hypotension, and cerebral hypoxia. Consciousness typically recovers spontaneously, and no focal neurological signs are present.

Vasovagal syncope is most commonly observed in school-aged children, with a higher prevalence among girls than boys. It typically occurs suddenly upon assuming an upright or seated position. Prodromal symptoms may include brief dizziness, impaired concentration, pallor, nausea, vomiting, diaphoresis, and unsteadiness while standing. Subsequently, heart rate slows and blood pressure gradually declines, leading to loss of consciousness lasting several seconds to several minutes. Upon regaining consciousness, patients may experience fatigue, lightheadedness, or other discomforts; in severe cases, post-ictal symptoms such as amnesia, mental confusion, or headache may occur and persist for 1–2 days before resolving.Physical examination during an episode may reveal hypotension, bradycardia, and mydriasis; however, interictal examinations are typically unremarkable.