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Aids to Diagnosis - Blackout

A blackout is a transient loss of consciousness.  There are many causes.  In most cases the most likely cause can be determined clinically, by history and examination.

Some pointers:

1.      An eye-witness account always helps.

2.      TIA’s only rarely cause loss of consciousness.

3.      Seizure and syncope are easily confused but the implications are very different. They can be separated by history (see below).  EEG is not usually used as a diagnostic test, and is more commonly used to classify epilepsy once the diagnosis has been made.

4.      Onset of epilepsy is most common in children, young adults and the elderly.

5.      Measuring erect and supine BP and a resting ECG are often helpful.

6.      Jerking limbs (albeit short-lived) can occur in syncope.


Separating Syncope from Seizure


  Syncope Seizure
Previous history? Often with similar precipitant

Epilepsy or febrile seizures in childhood

Learning disability or birth trauma

Duration < 30 seconds 2-3 minutes or more
Post-ictal confusion < 30 seconds 2 minutes to 24 hours
Precipitant Present in 50% (eg exercise, heavy meal, alcohol, micturition, heat, posture, cough) None
Colour during attack Pale Blue
Frothing at the mouth Rare Common
Incontinence Common Common
Tongue bite Rare Common
Vertiginous onset Common Rare
Feel of impending loss of consciousness Common Rare


If you decide to refer the patient it would be helpful if they or an eye-witness could complete this downloadable questionnaire:


Other Epilepsy mimics

Non-epileptic attack disorder/Pseudoseizures/Psychogenic seizures: Provoked by stress.  May be past history.  Undulating motor activity.  Asynchronous arm and leg movement.  Pelvic thrusting. Closed eyes, resistant to opening.  No cyanosis. Duration > 2minutes.

TIA: Sudden onset without progression.  Negative rather than positive features.


What to do (if it is a seizure)

Most patients can go home but sometimes admission is essential:

1.  If the patient hasn't fully recovered

2.  If the patient is febrile or unwell in some other way

3.  If the patient has focal neurological signs

4.  If they have more than one seizure within 24 hours


Where to refer a patient following a first seizure:

If it is a straightforward seizure and without other medical issues the patient can be referred to Sue Higgins in the epilepsy nurse first fit clinic (where they will usually be briefly reviewed by a consultant or seen subsequently). The epilepsy nurse first fit clinic is to see patients rapidly following a definite and uncomplicated first seizure for initiation of investigation, provision of information and to rapidly identify those at risk of recurrent seizures.

If there are other medical issues or diagnostic doubt they should instead be referred urgently to neurology consultant clinic.

When to start anti-convulsants in patients presenting with seizures:

Treat status.  For most other patients it is better to wait for their neurology appointment and then make an informed decision

What other patients should you refer?

We would like you to know about all patients who present to A&E with seizures, even in the context of  established epilepsy. If they are known to us already this can alert us to deteriorating control: please inform the consultant concerned or Sue Higgins.


What patients needn't you refer?

If the patient has seizures that have already been investigated and are part of alcohol or drug related problems then they need to be referred to appropriate agency who can involve us in the management of their epilepsy if they need, rather than referring these patients directly. 

If they are known to and under care of the learning disability team then they can be referred to that team via the 2gether trust; we do not need to see them.


What do to if it's Syncope

All patients should be examined, have erect and supine blood pressure measured, and have an ECG.  A syncope clinic takes place at CGH, managed by Dr Deering.  For further information about diagnosis and management, please click visit the Syncope website.


 Driving regulations in Syncope

The at-a-glance guide to the DVLA rules is available.  The table below shows the DVLA guidance on suspected syncope. 

Neurological Disorders

Group 1

Entitlement ODL - CAR, M/CYCLE



1. Simple faint. Defnite provocational factors with associated prodromal symptoms and which are unlikely to occur whilst sitting or lying. Benign in nature. If recurrent will need to check the three 'Ps' apply on each occaision (provocation/prodrome/postural). If not see Number 3 below

No driving restrictions. DVLA need not be notified NB Cough Syncope. No driving restrictions. DVLA need not be notified
2. Loss of consciousness/ loss of or altered awareness likely to be unexplained syncope and low risk of re-occurance. These have no relevent abnormality on CVS and neurological examination and normal ECG Can drive 4 weeks after event NB Cough Syncope. Can drive 3 months after event
3. Loss of consciousness/ loss of or altered awareness likely to be unexplained syncope and high risk of re-occurrence.
Factors indicating high risk:
(a) abnormal ECG
(b) clinical evidence of structural heart disease
(c) syncope causing injury, occurring at the wheel or whilst sitting or lying
(d) more than one episode in previous six months.
Further investigations such as ambulatory ECG (48hrs), echocardiography and exercise testing may be indicated after specialist opinion has been sought.

Can drive 4 weeks after the event if the cause has been identified and treated.

If no cause identified, then require 6 months off.

NB Cough Syncope. 

Can drive after 3 months if the cause has been identified and treated.

If no cause identified, then licence refused/revoked for one year

4. Presumed loss of consciousness/loss of or altered awareness with seizure markers
The category is for those where there is a strong clinical suspicion of epilepsy but no definite evidence.
The seizure markers act as indicators and are not absolutes – unconsciousness for more than 5 mins.
- amnesia greater than 5 mins
- injury
- tongue biting
- incontinence
- remain conscious but with confused behaviour
- headache post attack
1 year refusal/revocation 5 years refusal/revocation
5. Loss of consciousness/loss of or altered awareness with no clinical pointers. This category will have had appropriate neurology and cardiac opinion and investigations but with no abnormality detected.
Refuse/revoke 6 months  Refuse/revoke 1 year