Loss of consciousness

Definition

Syncope is a temporary loss of consciousness or ‘fainting’. Syncope is a result of an underlying medical condition.

Cause

Syncope can be related to multiple causes; some mild such as overheating or dehydration, some more serious, such as heart conditions or blood flow obstructions.

The most common type of syncope however, is Neurally mediated Syncope (NMS). NMS is causes by hypersensitivity of the autonomic nervous system while responding to different stressors.

Stressors that are believed to contribute to NMS include orthostatic stress, emotional stress, coughing, and exercise. However, orthostatic stress is considered to be the most common trigger for NMS.

Orthostatic Stress

This trigger involves a decreased blood supply returning to the heart (that can be related to multiple factors), which in turn means that Blood Pressure will decrease, and in an effort to regulate the heart rate and blood pressure, the heart receptors will trigger a neural signal to the brain that will lead to decreased heart rate and blood pressure and fainting (syncope). 

Symptoms

NMS is usually experienced when the person is standing. The person may feel:

  • Nausea
  • Sensation of warmth
  • Lightheadedness
  • Visual disturbance “grayout” 
Diagnosis

Before a diagnosis of NMS can be confirmed, other medical causes for the syncope must be ruled out. Patients will receive a full evaluation including a history and physical examination.

If the cause is still not clear, the physician will conduct assessments to rule out cardiac disease, and this may include blood pressure and heart rate monitoring, ECG, and echocardiogram.

In conjunction with the Cardiac Center, NMS can be further confirmed through the “head-up tilt-table” test and EKG monitoring. This test induces orthostatic stress in a controlled environment.

Treatment

NMS is benign in nature, but can affect quality of life. There are strategies that can be adopted to treat NMS, which include increasing fluid and salt intake. Ensuring that you remain hydrated, especially in the summer heat, avoid being in extreme heat, reduce alcohol consumption and avoid standing for long periods of time.

If the syncope is cardiac in origin, doctors may consider medications to control blood pressure and heart rate.