Vasovagal or Neurocardiogenic or Neurally Mediated Syncope: (Faint, Swoon)

Presentation

The patient experiences a brief loss of consciousness, preceded by a feeling of lightheadedness, a sense of warmth and nausea, and the awareness of passing out. This may or may not be accompanied by weakness and diaphoresis. In addition, the patient may or may not experience ringing in the ears or a sensation of tunnel vision.

First, there is a period of sympathetic tone, with increased pulse and blood pressure, in anticipation of some stressful incident, such as bad news, an upsetting sight, or a painful procedure. Immediately after or during the stressful occurrence, there is a precipitous drop in sympathetic tone and/or surge in parasympathetic tone, resulting in peripheral vasodilatation or bradycardia, or both, leading to hypotension and causing the victim to lose postural tone, fall down, and lose consciousness.

Once the patient is in a horizontal position, normal skin color, normal pulse, and consciousness return within seconds. This time period may be extended if the patient is maintained in an upright sitting position.

Transient bradycardia and a few myoclonic limb jerks or tonic spasms (syncopal convulsions) may accompany vasovagal syncope, but there are no sustained seizures, incontinence, lateral tongue biting, palpitations, dysrhythmias, or injuries beyond a minor contusion or laceration resulting from the fall. Ordinarily, the victim spontaneously revives within a brief period of time, suffers no sequelae, and can recall the events leading up to the faint.

The whole process may transpire in an emergency department or a clinic setting, or a patient may have fainted elsewhere, in which case the diagnostic challenge is to reconstruct what happened to rule out other causes of syncope.