Transient loss of consciousness (TLoC), very commonly described by patients as a blackout, is a loss of consciousness usually resulting in complete recovery. Patients will often present to a GP or to A&E following an episode and this should always be investigated to ascertain the underlying cause of the TLoC.
Misdiagnosis is not unknown, so medical staff should follow current NICE guidelines when assessing a patient over 16 years of age presenting with blackouts.
You should obtain information from the patient and/or any witnesses to the TLoC event. Ask them to describe what happened before, during and immediately after. Things to ask include:
· Was the patient hot and sweating
· How did they look eg were they pale, were their eyes open or shut
· Were they experiencing limbs jerking
· Did they bite their tongue or otherwise receive an injury immediately before the event
An uncomplicated faint may be diagnosed where there are no indications suggestive of an alternative diagnosis. For example, a brief seizure can occur during a TLoC but this doesn’t necessarily mean epilepsy. An uncomplicated faint can be caused by the 3 ‘Ps’:
· Posture – prolonged standing with no opportunity to sit or lie down
· Provoking factors such as pain or a medical procedure
· Prodromal symptoms such as feeling hot and sweaty
These features along with a pallor which is not normal for the patient are cause for consideration that the blackout may not be epilepsy-related.
The following circumstances are indications that a patient who presents with a TLoC should be referred for cardiovascular assessment within 24 hours:
· ECG abnormality
· History or physical signs of heart failure
· Family history of sudden cardiac death under the age of 40 and/or an inherited cardiac condition
· A heart murmur
· New or unexplained breathlessness
· TLoC during exertion
For a patient over 65 years of age who has had a TLoC without prodromal symptoms, you should consider referring them for cardiovascular assessment within 24 hours.
Some blackouts or faints can be strongly suggestive of epilepsy and these can be discerned by specific features. Refer for specialist assessment within 2 weeks if you see any of these:
· A bitten tongue
· Turning the head to one side during a TLoC
· No memory of abnormal behaviour before, during or after the TLoC, prodromal déjà vu or jamais vu
· Confusion after the event
· Prolonged limb jerking or unusual posturing
Where there is a suspected cardiac arrhythmic cause of syncope, an ambulatory ECG should be offered but this should be chosen based on the patient’s history and frequency of TLoC. Do not offer a tilt test initially.
Where there is suspected vasovagal syncope with recurrent TLoC which is impacting the quality of life consider a tilt test to ascertain whether a severe cardioinhibitory response (usually asystole) is present.
Where the patient has experienced syncope during exercise, offer exercise testing within 7 days unless there is a possible contraindication such as aortic stenosis or hypertrophic cardiomyopathy. Initial assessment by imaging will be required here. The patient should be advised to stop exercising until told otherwise.
It is also important to inform the patient that they may need to stop driving and contact the DVLA unless the episode is clearly a simple faint.