SAMIR S. SHAH
DEFINITION OF THE COMPLAINT
Syncope is generally thought of as a temporary, but sudden, loss of consciousness and postural tone. It is due to a reversible interruption of cerebral perfusion, typically caused by a deficit of cerebral oxygen or glucose delivery. The deficit in oxygen delivery may be caused by decreased cardiac output, peripheral vasodilatation, or obstruction of cerebral blood flow. It is important to differentiate the episode of syncope from other etiologies that appear like syncope, such as seizure and near syncopal episodes. Painful events, episodes of micturition or defecation, and stress frequently precede syncope. Sweating and nausea prior to the episode are common as well. Seizures frequently have no prodromal period; however, they may be associated with an aura prior to the event. Seizures are frequently associated with tonic-clonic movements during the event; however, syncopal events that last 20 seconds or longer can also be associated with very brief tonic-clonic movements. Confusion after the event, prolonged return to normal state of consciousness, and unconsciousness lasting longer than 5 minutes suggests seizure activity. During near syncopal episodes the patient feels as though they are about to lose consciousness, but do not actually become unconscious.
Syncope is a common complaint in pediatrics. Approximately 15% of children will have a syncopal episode by the time they reach adulthood.
COMPLAINT BY CAUSE AND FREQUENCY
Pediatric causes of syncope are generally benign, but syncope may signal serious life-threatening causes, particularly if it is recurrent or if there is a family history of sudden cardiac arrest. In children, common causes of syncope include vasovagal episodes, orthostatic hypotension, and breath-holding spells (Table 18-1). In contrast, most adult syncope is due to a cardiac cause. The goal in evaluating syncope is to differentiate benign causes from a more worrisome etiology (Table 18-2).
TABLE 18-1. Differential diagnosis by age.
TABLE 18-2. Differential diagnosis of syncope by etiology.
• Were there any palpitations or “funny heart beats”?
—If the child reports palpitations, then a cardiac dysrhythmia should be considered.
• Did it occur with activity?
—Syncope that occurs with activity is particularly concerning for idiopathic hypertrophic cardio-myopathy.
• Did it occur without warning?
—Syncope that occurs suddenly and without warning should raise concern for a cardiac arrhythmia.
• Were there prodromal symptoms?
—Acute orthostatic intolerance (e.g., simple faint) typically occurs in the context of known precipitants (e.g., standing, heat, emotion) and prodromal symptoms (e.g., nausea, blurred vision, headache).
• Did it happen on standing?
—Orthostatic hypotension is associated with syncope on standing.
• Was there pain, fear, or some disturbing visual sight prior to the syncope?
—Strong emotional impulses may stimulate a vasovagal response and ultimately syncope.
• Was there any seizure-like activity?
—Brief seizure-like motor activity can occur with vasovagal syncope. Prolonged seizure activity should prompt a more thorough seizure workup. There is no significant postictal period with the seizure-like activity associated with syncope.
• How long did it take to return to baseline?
—Vasovagal syncope is associated with a relatively quick (minutes) return to baseline mental status as soon as cerebral blood flow is restored. If there is a delay in assuming a recumbent position, there may be a longer delay in return to baseline mental status. Increased duration of unconsciousness or confusion suggests seizures rather than syncope.
• Was there a history of trauma?
—A recent history of head trauma raises concern for intracranial hemorrhage.
• Is there a family history of sudden death, including common causes such as drowning or auto accidents?
—A family history of sudden death should raise suspicion for cardiac arrhythmias.
• Is there a history of anemia?
—Anemic patients may be more likely to have a syncopal episode because of decreased cerebral oxygen delivery.