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Syncope and Adolescent Dysautonomia

Updated: May 7, 2021

Claire R. Galvin, HBSc; Kathryn R. Armstrong, MB, ChB; Shubhayan Sanatani, MD, FRCP


Syncope is defined as a transient loss of consciousness associated with an inability to maintain postural tone which is followed by a spontaneous or rapid recovery.[1,2] The cumulative incidence of syncope by 60 years of age is reported to be 30%-40%.[2,3] Incidence of syncope increases in adolescence.[4] The age of first faint is typically reported to be around 13 years of age.[5] In children and adolescents, the most common form of syncope is called vasovagal syncope (VVS) due to a transient dysfunction of the autonomic nervous system (ANS).[2]

TABLE 1 Examples of Cardiac Causes of Syncope[5]

While VVS is the most common form of syncope in children and adolescents, it is important to evaluate whether there are any underlying features that would indicate the presence of a cardiac cause.[6] Cardiac or neurologic syncope have more serious implications for patient health and outcomes. Cardiac syncope is caused by heart conditions including conditions categorized by electrical disturbances or structural heart disease.[6] Classification of cardiac causes are found in Table 1. Neurologic syncope causes include seizures and narcolepsy.[6]

The most important diagnostic tool for syncope evaluation is patient history. The presence of a prodrome such as vision change, clammy skin, and dizziness as well as an unremarkable physical exam and family history suggest VVS with no further investigations needed.[6] The absence of a prodrome prompts further clinical evaluation as it is an indication of cardiac causes. A patient with a family history of sudden death, arrhythmias, seizures, structural heart disease, or an abnormal cardiac examination should prompt further investigations by a syncope specialist.[6] While these types of syncope are less common, they are important to distinguish from VVS as they may represent an underlying cardiac or neurologic cause. The underlying cause of VVS is due to a transient dysfunction of the ANS. Heart rate and blood pressure regulated by the ANS decreases suddenly, which causes a reduction in blood flow to the brain leading to loss of consciousness. Loss of consciousness can be mediated with patient education on presyncopal prodromes as well as potential triggers, and adequate hydration.[6,7] A concise list of important factors in syncopal evaluation is found in Table 2.

To read the full article, please go to the August 2020 Issue of CCT.


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