Reflex syncope in children and adolescents.

Syncope can be defined as a temporary loss of consciousness and postural tone secondary to a lack of adequate cerebral blood perfusion. The incidence of syncope coming to medical attention appears to be clearly increased in two age groups—that is, in the young and in the old (fig 1). An incidence peak occurs around the age of 15 years, with females having more than twice the incidence of males. 2 Syncope is an infrequent occurrence in adults. The incidence of syncope progressively increases over the age of about 40 years to become high in the older age groups. A lower peak occurs in older infants and toddlers, most commonly referred to as ‘‘breath-holding spells’’. The incidence of syncope in young subjects coming to medical attention varies from approximately 0.5 to 3 cases per 1000 (0.05–0.3%). Syncopal events which do not reach medical attention occur much more frequently. In fact, the recently published results of a survey of students averaging 20 years of age demonstrated that about 20% of males and 50% of females report to have experienced at least one syncopal episode. By comparison, the prevalence of seizures in a similar age group is about 5 per 1000 (0.5%) and cardiac syncope (that is, cardiac arrhythmias or structural heart disease) is even far less common. By far the most common cause of syncope in young subjects is a reflex syncopal event and in particular a vasovagal faint This disorder is the focus of the present review.