[Sudden loss of consciousness in childhood]

Sudden loss of consciousness in childhood presents itself usually as a syncope and occurs in approximately 15% of all children. Although syncope in the pediatric age group appears to be an isolated phenomenon with good prognosis, it could also be a manifestation of a life-threatening disease. Thus, even the first syncope should be evaluated in children. A thorough history and a careful physical examination with special attention to cardiovascular and neurologic abnormalities usually point to the etiology of the syncope and must result in the appropriate laboratory tests. About 50% of pediatric syncopes are non-cardiovascular, 20 to 30% are cardiovascular, and 20 to 30% are of unknown etiology. The most frequent syncope in childhood is neurocardiogenic. It is important to distinguish neurocardiogenic syncope from cardiac syncope and epileptic seizures. Neurocardiogenic and cardiac syncopes can be discriminated from epileptic seizures by their usually shorter duration of unconsciousness and rare postsyncopal disorientation. Cardiac syncope is rare in children with a structurally normal heart and may be associated with Wolff-Parkinson-White syndrome, long QT syndrome or congenital AV block. Children with congenital heart defects and cardiomyopathies who present with syncope must raise a high degree of suspicion for a cardiac syncope. Cardiac syncopes often yield a poor prognosis with substantial percentages of sudden death; therefore, a vigorous attempt has to be made to diagnose and adequately treat cardiac syncope in children.