[Etiologic and clinical characteristics of syncope in children]

Syncope is a common problem in children and adolescents. Such an event may have multiple possible causes, ranging from benign conditions to life-threatening diseases. Syncope is a major challenge for the practicing physicians. It is very important to know the etiologic and clinical characteristics of syncope in children. This study aimed to improve diagnostic efficacy of syncope in children by analyzing the etiology and clinical characteristics of syncope.

The investigators retrospectively analyzed the causes of syncope and diagnostic workup of 154 consecutive children seen in Department of Pediatrics, Peking University First Hospital because of a syncopal event.

Autonomic-mediated reflex syncope (AMS) was the most common cause of syncope (65.6%), whereas cardiac disorders were found in 10 cases (6.5%) comprising the second cause of syncope in children. Other causes included psychologic problems and neurological and metabolic disorders. Although many causes were studied, 25 cases (16.2%) were found to have uncertain etiologies yet. The children with AMS were commonly seen in pubertal girls, and they had clear inducement of syncope and prodromes. The children with cardiac syncope often had history of cardiac diseases, and they were often younger than those with AMS. Lack of prodromes of syncope, exercise-related syncope, syncope spells seen in any body position, frequent syncope spells and sudden death in family were clues of cardiac syncope. Neurological disorders should be considered if there are any of the followings: syncope with seizure activity, syncope spells seen in any position, and a postictal phase of disorientation or neurologic abnormal signs. A metabolic cause was entertained when the child had a history of metabolic diseases, prolonged anger, or violent vomiting and diarrhea. Children with psychiatric disorders were adolescent girls with prolonged syncope spells, and had more frequent syncopal episodes. Most children with syncope were evaluated by many of diagnostic tests, but most of those tests were not goal-directed approach. Since persons with cardiac syncope were at increased risk for death from any cause, electrocardiography was recommended in almost all children with syncope. Neurologic testing including electroencephalography, computed tomography, etc. were rarely helpful unless neurologic signs and symptoms are present. Holter electrocardiography and echocardiography were most useful in children with suspected cardiac syncope. There was little benefit of screening cardiac enzyme in children with syncope. Routine blood tests (blood electrolytes and blood glucose, etc) rarely yield diagnostically useful information unless the children had the history of metabolic diseases. Head-up tilt testing was most useful in children with recurrent syncope in whom heart disease was not suspected. The children with frequent syncope, long lasting syncopal episode and clear psychiatric inducement of syncope should be evaluated by psychiatric testing.

Syncope in children may result from a wide variety of causes, and clinicians often use a wide range of investigation to try to achieve a diagnosis. But most of investigations have low diagnostic yield. Thorough history taking, physical examination and electrocardiography are the core of the syncope workup.