Collapse with loss of awareness

General points

• Vasovagal syncope (simple faint) accounts for most collapses with loss of awareness in patients of good general health. Vasovagal syncope can sometimes be confused with other, more serious causes of collapse with loss of awareness, such as seizures and cardiac syncope.

• Accounts of the incident from witnesses, as well as from the patient, are important in reaching a diagnosis. Phoning a witness is time well spent.

• A collapse is a dramatic event, and terms such as “fitting” and “seizure” may be used. It is important to get a description rather than a label.

• Do not rely too much on any one feature of the event. Instead develop a mind's eye view of events before, during, and after the attack.

What issues you should cover

What was the patient doing when it happened?— To make a confident diagnosis of vasovagal syncope, expect a precipitating factor such as prolonged standing, dehydration, heat, fear, or pain. Cardiac syncope and seizures are usually spontaneous; collapse during exercise is a “red flag” sign for cardiology referral.

What was the patient's last memory?— Expect a prodrome in vasovagal syncope. Common precursor symptoms are light headedness, feeling hot, nausea, and dizziness. Just before losing consciousness the patient may experience dulled hearing and changed vision (blurring, spots, or dull vision). Cardiac syncope usually has no warning, although palpitations or light headedness may be recalled. Similarly, seizures often have no warning, although they can be preceded by an aura such as a déjà vu experience or a rising sensation in the abdomen.

What did the eyewitnesses see?— Vasovagal syncope occurs in a standing or sometimes a sitting position. It is associated with pallor and brief loss of consciousness. Twitching and jerking are often seen; this can be prolonged if during the collapse the head remains above the level of the heart. Falling stiffly followed by sustained, rhythmical jerking of all the limbs indicates a tonic-clonic seizure. A collapse with loss of awareness but no motor phenomena would be highly unlikely to be a seizure. Pallor and brief twitching may be seen in cardiac syncope.

What was the patient's first memory on coming round?— Tonic-clonic seizures are followed by a period of confusion, disorientation, and amnesia. Determine this from a witness and clarify the patient's first clear memories. After vasovagal syncope individuals may feel sick and sweaty, then tired for many hours, but immediately on coming round they can recollect conversations and events that took place before the event.

What you should do

Examination— Patients who have had vasovagal syncope or a seizure usually have no abnormal examination findings. The purpose of examination is to reassure the patient and to look for signs of cardiac disease that indicate cardiac syncope. Check her pulse, lying and standing blood pressure, and heart sounds.

Investigation— In cases of vasovagal syncope investigation results should be normal. Only occasionally is there an underlying cause. Consider checking full blood count and urea, electrolytes, and glucose concentrations and doing a pregnancy test. The guidelines of the UK National Institute of Health and Clinical Excellence suggest electrocardiography in all collapses with loss of awareness to check for abnormalities such as arrhythmias and long QT syndrome.

Management— A clear explanation and reassurance are important, as vasovagal syncope can be frightening. Advise her to lie down should warning symptoms occur again and to avoid the precipitants. If you suspect cardiac syncope or seizure then refer her to the appropriate specialist and advise her not to drive until she has been seen.