Syncope, or fainting, is the sudden loss of consciousness and the inability to maintain erect posture. It is extremely common and can be seen in 10 percent of individuals. Syncope is usually benign. However, there are malignant forms and these must be considered and identified at the time of presentation.
The malignant forms of syncope are primary neurological (seizures, space occupying lesions, neuro-degenerative diseases, etc.), respiratory (airway obstruction, central hypoventilation, etc.) and cardiac. The cardiac causes of syncope are anatomic (“Tetralogy spells”, hypertrophic cardiomyopathy, etc.), ischemic (Kawasaki disease, congenital anomalies of the coronary arteries) or arrhythmic.
While it is imperative to identify and treat the malignant forms, the distinction from benign syncope is usually quick and obvious. Malignant syncopes have a sudden onset without a prodrome. If they are respiratory related, the patient first becomes cyanotic, and if cardiac, the patient may feel palpitations or appear gray and ashen, not pale.
Benign syncope has many interchangeable names: vaso-vagal syncope, autonomic dysfunction, orthostatic intolerance, neurocardiogenic syncope and simple fainting. It is caused by a dysregulation of the central nervous system homeostatic mechanism with a fall in blood pressure (vaso-depressor), fall in heart rate (cardio-inhibitory) or both (mixed). Following prolonged standing, rapid rising, sudden pain, a startle or the sight of blood, there is an initial hyper-stimulation of adrenergic tone (“Fight or flight system”) followed by an over-compensation of vagal tone. The patient may initially feel palpitations followed by nausea, diaphoresis and appear pale (“White as a ghost”). They will then slump to the floor and may even experience a secondary seizure (“reflex anoxic seizure”).
Evaluation and Treatment
Benign syncope can be recurrent; one-time events need no treatment. First-line treatment is dietary salt and volume loading (“Pop and Potato chips”). This will increase the intravascular volume and prevent the cascade of the autonomic nervous system over-compensating responses. At the onset of a vaso-vagal event, complete syncope can usually be averted by just sitting down until the event resolves in usually one to two minutes.
Treatment consists of eight glasses of liquid per day along with a salty snack (potato chips, corn chips, saltines, etc.) and is usually required for 6 months to two years.
Initial evaluation is a detailed history of the event, medical and family histories, exam and an ECG. If the evaluation is consistent with benign syncope, no further work up is necessary and the primary care physician may begin treatment.
Referral to a specialist is indicated if there is:
- Sudden onset with an injury producing fall (no prodrome)
- Family history of cardiomyopathy or sudden death
- Syncope during exercise