“Syncope is a symptom complex that is composed of a brief loss of consciousness associated with an inability to maintain postural tone that spontaneously and completely resolves without medical intervention. It is distinct from vertigo, seizures, coma, and states of altered consciousness.”1


A common approach to determining the etiology of syncope, and the brief cerebral hypoperfusion that causes it, is to classify it into CARDIAC and NON-CARDIAC causes. The following list describes the possible causes1:


  • CARDIAC-related Syncope:
    • The causes of cardiac syncope are divided into two categories: structural disease and dysrhythmias
    • Important ECG findings in syncopal patients. (Great Mnemonic to help remember the key ECG findings) 
  • NON-CARDIAC Syncope:
    • Vasovagal or Neurally/reflex-mediated syncope:
      • Vasovagal syncope, a form of reflex-mediated or neurally mediated syncope, is associated with inappropriate vasodilatation, bradycardia, or both, as a result of inappropriate vagal or sympathetic tone.
    • Orthostatic syncope:
      • Orthostatic syncope is suggested when postural hypotension is associated with syncope or presyncope.
    • Psychiatric illness:
      • A psychiatric cause for syncope should be one of exclusion, assigned only after organic causes have been excluded.
    • Neurologic Syncope:
      • Neurologic causes of syncope are rare. To meet the definition of syncope, symptoms must be transient and with no persistent neurologic deficits.
    • Medication-induced syncope:
      • Medications may contribute to syncope by a variety of means but the most common is orthostasis.


Feeling comfortable assessing the syncopal patient is very important given the variety of possible causes. A thorough review of the categories, exam findings, concerning features, ECG features, and risk stratification in patients with syncope is provided by EM Cases. 


Click HERE for a list of all mentioned FOAM resources.


  1. Quinn, J., Chapter 56, “Syncope”. Tintinalli’s Emergency Medicine – A Comprehensive Study Guide. J Tintinalli. 7th ed. McGraw-Hill Education, 2010. 


Prepared by Alex Mungham PGY1 FM – University of Ottawa