Dr. YK Amdekar writes on the evaluation of sudden fainting episodes or syncope which presents as a symptom for several underlying issues ranging from vasovagal attacks to heart defects and autonomic nervous system dysfunction. Here he lists key practice points and clinical approach to take while evaluating patients.

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Sudden fainting referred to as syncope presents with a sudden brief loss of postural tone and consciousness due to transient cessation of cerebral blood flow as a result of either hypotension or bradycardia. Typically, the attack occurs while standing due to blood pooling in the lower limbs due to gravity resulting in a fall in blood pressure resulting in transient hypoperfusion of the brain. It is frequently preceded by a feeling of warmth or nausea. If the attack is prolonged, a seizure may occur. Skin is pale and sweaty, eyes are closed and there is no bladder or bowel incontinence. Symptoms other than fainting are often present such as feeling drowsy, headache, unsteady or weak.

Several mechanisms are involved in the causation of such an episode and include autonomic nervous system dysfunction, auto-dysregulation of cerebral blood flow, endogenous vasodilator and low serum ferritin. The autonomic nervous system exercises control over many functions such as heart rate, blood pressure, bowel and bladder and such control is involuntary.

Key practice points

1. Fainting may occur in healthy individuals as a vasovagal attack triggered by anxiety, fear, stress, pain or hunger and is typically experienced by an older school-going child while standing at the morning assembly.
2. Fainting may also be caused by a variety of disorders such as heart defects (rhythm disturbances, arrhythmias including tachycardia, WPW syndrome or long QT syndrome, myocardial dysfunction, hypertrophic cardiomyopathy, outflow tract obstruction), nervous system disorders (seizure, stroke, transient ischaemic attack, migraine, normal pressure hydrocephalus. autonomic nervous system dysfunction), severe anaemia, hypoglycaemia, dyselectrolytemia, sepsis, toxins and drugs.
3. Other situational syncope includes dehydration, hyperventilation, cough and micturition syncope. Postural hypotension is seen in elder people due to sudden change in body stance.

Differential diagnosis

Syncope has to be differentiated from primary seizure disorder or vertigo. Besides, the underlying cause of syncope has to be established. History is most important to be obtained from a witness with second-to-second details of the event. Such detailed history is often unavailable, but attempts must be done to get as much information as one can get. This is far more important because, often, the physical examination does not reveal any abnormality. Subsequent investigations and management depend on the provisional diagnosis.

Clinical approach

1. The first step is to confirm a fainting episode as syncope. A single episode of a standard pattern in a healthy child occurring in a typical situation does not pose a problem. Prolonged attack or recurrent episodes need careful assessment.
   1. A seizure may occur in any position. Eyes are open and the attack is followed by post-ictal drowsiness, at times with bladder incontinence or tongue biting as against eyes closed, no bladder incontinence, tongue biting or drowsiness following the event. In fact, a child with a syncope stands up immediately after a brief period of unconsciousness.
   2. Vertigo presents with a feeling of spinning, unsteadiness, dizziness without loss of consciousness or feeling surrounding objects rotating. It is worsened with a change in position and is often accompanied by nausea or vomiting.
2. The next step is to find the cause, once syncope is confirmed. A single typical episode with a quick and complete recovery in an otherwise healthy child without any physical examination abnormalities or obvious disorder does not need any investigations and the patient or parents must be assured of its benign nature.
   1. In case the first attack occurs during physical exercise such as playing, it indicates a probable heart defect. Besides, prolonged attack or recurrent episodes justify further assessment. Physical examination may reveal evidence of heart or neurological disease, severe anaemia or other acute conditions and further relevant tests can be ordered or the patient referred for speciality opinion.
   2. Repeated physical examination and also in different positions may detect autonomic nervous system abnormality. The real challenge is to plan investigations in the absence of any clue on physical examination.
3. It is important to rule out cardiac rhythm disturbance, especially long QT syndrome or any other silent heart defect, for which ECG or Holter monitoring and echocardiogram would be necessary. EEG may be abnormal in a seizure disorder, however normal EEG does not rule it out.
4. Video-EEG may be considered if a seizure is highly suspected that could record tracings for 24 hours. Neuro-imaging is rarely necessary. Tilt-table test can detect changes in heart rate and blood pressure on sudden changing position from lying down to sitting and standing.
5. Fasting blood sugar is considered to rule out hypoglycemia.

Management

Appropriate therapy depends on the specific cause of syncope and is best left to a specialist. In an apparently benign and situational syncope, preventive measures may be considered. They include diet modification such as small frequent feeds, an adequate amount of salt and water, sleeping with the head elevated, slow change of body position and avoiding caffeine or alcohol.

Biofeedback may be tried. It consists of a mind-body technique that involves using auditory or visual feedback to gain control over involuntary body functions such as blood flow, heart rate and blood pressure. Essentially, it is a form of relaxation technique and meditation and it is useful in cases of chronic stress, anxiety, or pain.

In summary, the diagnosis of syncope is based on history and the cause is commonly benign. However, if syncope occurs during physical exercise or if it is prolonged or recurrent, it needs further investigation and specific management. In benign syncope, relaxation technique and meditation is useful.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.