Feature Article

The assessment of blackouts

Ernest R Somerville, Josephine C Gutierrez



Although most transient episodes of loss of consciousnes are benign, they may signal serious cardiac or brain pathology or be a symptom of an illness not primarily involving the cardiovascular or central nervous systems.

Key Points

  • Most blackouts are caused by syncope or seizure.
  • Syncope and seizure can usually be confidently distinguished by the history.
  • Description by a witness to the event is an essential part of the history.
  • Syncope is often misdiagnosed as seizure when it is accompanied by convulsive movements.
  • Syncope is usually benign and does not need investigation, but when certain features are present, cardiac disorders, especially arrhythmias, should be excluded.
  • Seizures have a wide range of causes and affected patients require neurological referral.