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'Blackout' patient needs to drive



Ethel is a 48-year-old social worker who 'blacked out' yesterday at work. She felt perfectly well a few minutes later but was driven home by a friend. She used to faint as a teenager but has not had any problem since the age of 16. She is not on any medication. Ethel very much needs to drive

as part of her job and is keen to

get back to the office.

Dr Tanvir Jamil discusses.

Isn't this just a faint and she can be reassured?

Possibly. But the diagnosis of syncope seems to follow the rule of halves: after initial assessment only half the cases of syncope have a definite diagnosis.

If you investigate the remaining half then only half of those will be diagnosed. There are almost 200 causes of syncope (apart from a simple faint!). Rather then memorise (and then forget) this list it is much more logical and easier to divide the causes of syncope into cardiovascular and non-cardiovascular.

The majority of 'blackouts' are cardiovascular in origin caused by vasovagal syncope. A few are caused by arrhythmias. Non-cardiovascular problems are relatively infrequent but include metabolic (eg hypoglycaemia), neurological (eg fits, TIAs), and psychiatric (hysteria, panic) disorders.

In general the commonest causes of syncope are bradyarrhythmia in the elderly and vasovagal in the young. Interestingly co-existing heart disease in vasovagal syncope is rare.

What is the initial assessment?

History is the most important step. Additional information from a friend, family member or observer can be invaluable. Remember the key historical clues (see box). The drug history needs to focus on recent changes and hypotensive agents.

Would a full examination reveal anything else useful?

An examination is often more useful for ruling out causes of syncope than ruling them in. Patients should have their blood pressure checked for postural drop. You may need to stand them up for up to three minutes to detect a drop.

Check also for obstructive etiologies such as aortic stenosis or HOCM. Finish with a brief neurological examination, especially if you suspect a primary neurological cause.

What investigations, if any, are worth doing?

If a clear diagnosis can be made from the history (eg vasovagal) then further investigations are not warranted. In most other cases an ECG would be the first step. It may point to significant structural heart disease which would need specialist referral.

If carotid hypersensitivity is suspected, carotid sinus massage can be attempted. Apply steady pressure on one side only, ideally while the patient is being monitored by ECG. Many other tests are often carried out by GPs as well as specialists although studies have indicated that they often yield very little. Examples include routine blood, ECG, EEG, treadmill tests, angiography, carotid doppler and brain imaging.

What about specific cardiovascular monitoring?

Holter monitoring is a 24-48 hour ECG recording with a patient diary of symptoms to determine correlation between symptoms and abnormalities.

Figures suggest only 2-4 per cent of patients have syncope while wearing the Holter so it rarely provides a conclusive diagnosis but often gives clues to a possible cause.

What can you advise a person with vasovagal syncope?

Reassurance about the benign nature of vasovagal syncope and use of simple self-help measures is often all that is required. Self-help includes:

·Avoid situations likely to induce syncope ­

eg standing in a queue, taking a long hot bath, eating a large meal in a warm restaurant

·If a collapse is imminent lie down flat propping your legs up on a chair or against a wall or sit down with your head between your knees

·Rock backwards and forwards on your heels

·Drink 200ml of water; this promptly increases blood pressure in normal subjects and may also be helpful in preventing vasovagal syncope

·Sleep with the head of your bed raised by about 10° ­ reduces urinary salt loss

·Endurance training, eg rowing, jogging.

Should we warn Ethel about driving?

If Ethel's problem turns out to be a 'simple faint' (definite provocation factors associated with prodromal symptoms and unlikely to occur while sitting or lying) there are no restrictions on driving.

For unexplained syncope but low risk of recurrence, Ethel can drive four weeks after the event. If the syncope is unexplained and there is a high risk of recurrence she can drive four weeks after the event if the cause has been identified and treated. If there is no cause identified she will not be allowed to drive for six months.

In general patients have a legal duty to inform the DVLA about any condition likely to affect their ability to drive safely.

When a patient contacts the DVLA they may be informed that they can continue to drive while investigations are being undertaken provided they have not been advised to cease doing so by their GP and/or specialist.

Key historical clues

General Duration and frequency; circumstances; prodrome; time to return to normal; drug history; duration of unresponsiveness

Vasovagal Warm prodrome; upright posture; return to

normal within minutes; averted syncopal spells (near misses); childhood fainting

Arrhythmia Sudden LOC; palpitations

Seizure Aura; tongue biting; tonic-clonic movements; incontinence; post-ictal state

Useful contacts

DVLA, Longview Road, Morriston, Swansea SA99 1TU, publishes: At a Glance Guide to the Current Medical Standards of Fitness to Drive

Tanvir Jamil is a GP in Burnham, Bucks

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