[Lipothymia and syncope in adolescents].
Syncope is the transient loss of consciousness and postural tone resulting from inadequate cerebral perfusion. The most common type of syncope in healthy children and adolescents is the vasovagal syncope, which is a benign and transient condition. The evaluation of syncopal children or adolescents is on a detailed history and physical examination. ECG is mandatary, other laboratory tests must be guided by pertinent positives or negatives in the history and physical examination. The pathology of syncope seems to follow a common pathway with many inciting stimuli. Cerebral perfusion is compromised by a transient decrease in cardiac output caused by vasomotor changes decreasing venous return, primary dysrhythmia, or impairment of cerebral vascular tone. Tilt table testing can be useful in selecting therapy by demonstrating the physiologic response leading to syncope in an individual patient. Treatment is usually targeted to those in whom syncope is recurred or has been associated with physical injury. In others, treatment involves removal or avoidance of agents that predispose to hypotension or dehydration, including alcohol, vasodilating anti-hypertensive medications, and diuretics. However, when these measures fail to prevent the recurrence of symptoms, pharmacologic therapy is usually recommended. The efficacy of beta blockers, midodrine and SRIs have been confirmed in randomized, prospective clinical trials. In addition to these 3 agents, there is also considerable clinical experience suggesting the value of fludrocortisone.