Syncope

Syncope is defined as a temporary loss of consciousness with loss of muscle tone and spontaneous recovery of consciousness.

Presyncope is defined as the feeling of an impending event with loss of consciousness. This feeling can manifest itself in the form of flickering before the eyes, nausea, dizziness, weakness or other symptoms.
Syncope and presyncope are relatively common events in adolescents up to the age of adulthood (15% of all adolescents, peak incidence 15-19 years). Girls are more frequently affected than boys.

The mechanism behind it is reduced blood flow to the brain, but a real cause for the dizziness is not always found.

There are various forms of syncope:

Cardiac syncope

Low-output syndrome with aortic stenosis, hypertrophic obstructive cardiomyopathy, pulmonary stenosis, pulmonary embolism, myocardial infarction with pump failure, pericardial tamponade, bradyarrhythmias (Adam-Stokes seizure), tachyarrhythmias

Circulatory syncope

Orthostatic syncope when suddenly standing up from a lying position
neurocardiogenic = vasovagal syncope
postprandial syncope in the elderly
hypovolaemic syncope
pressor syncope
Vena cava compression syndrome in pregnant women in the last trimester of pregnancy
Carotid sinus syndrome
Drug-induced, e.g. due to antihypertensive drugs

Cerebral syncope

Narcolepsy, cerebrovascular insufficiency
Metabolic syncope

Vasovagal or neurocardiogenic syncope

The most common form of syncope in children and adolescents is vasovagal or neurocardiogenic syncope. Certain triggers such as fear, pain, stress, prolonged standing initially cause a feeling of dizziness with sweating, "getting hot and cold", palpitations, nausea, pallor and finally loss of consciousness and tone. During long periods of standing, for example, the venous return flow to the heart is reduced, resulting in low blood pressure. The body's counter-regulation is usually an increase in heart rate to ensure sufficient blood flow to the brain. In some people, however, there is not an increase but a decrease in the heart rate and thus a loss of consciousness.

The initial assessment is carried out on an outpatient basis. A detailed medical history is taken from the patient and others. It is important to know the exact course of the syncope. In addition, the intake of medication, drugs or the presence of an underlying illness are also enquired about. A family history for long-Q-T syndrome and psychiatric illnesses must be taken. The physical examination includes a cardiological clarification and possibly extended examinations if a neurological disease is possible. (EEG, CT or MRI). Cardiovascular causes are clarified by means of an ECG, long-term ECG, echocardiography or exercise ECG.
The most common form, i.e. neurocardiogenic syncope, can be confirmed by the so-called tilt-table test. After lying down for 15 minutes, the patient is passively raised by 60-80° on a tilt table and kept in this position for approx. 20 minutes. Blood pressure, heart rate and symptoms are recorded. If the patient remains symptom-free, he is brought back into a horizontal position and a stress situation is provoked with a strong ß-mimetic (isoprenaline). The patient is then brought upright again. The test is negative if no symptoms occur despite successive dose increases up to a heart rate increase of 20-30/min.

Cerebrovascular syncope usually occurs when blood pressure is stable. It is caused by vasoconstriction of cerebral arteries and can be diagnosed by simultaneous transcranial Doppler in case of doubt. A differential diagnosis should always include psychogenic syncope, which requires psychiatric evaluation.

In addition to the tilt table procedure, a Schellong standing test can also be carried out. This involves documenting the patient's pulse and blood pressure behaviour after a change in position from lying to standing in order to prove or rule out orthostatic syncope.