QuestionSBA
QuestionChoice
This patient has had a simple faint, or vasovagal syncope. This is commonly positional, such as here following a long period of standing on the tube, and is often described as being preceded by tunnel vision or vision "closing in". A short period of convulsions can be normal. It can be differentiated from proper seizure activity by the lack of a post-ictal phase
33458
a
Vasovagal syncope
QuestionChoice
If this were an epileptic seizure, it might last longer than 15 seconds, be accompanied by classic seizure indicators such as incontinence or tongue biting and be followed by a post-ictal period. The positional nature of this episode, combined with the short course of the convulsions and rapid recovery of the patient to GCS 15, makes an epileptic event very unlikely
33459
b
Epileptic seizure
QuestionChoice
If a patient has severe enough hypoglycaemia to cause a collapse, you would expect some residual drowsiness, reflected in reduced GCS. Symptoms would also be expected to come on more gradually than in this stem
33462
e
Hypoglycaemia
QuestionChoice
In syncope relating to arrhythmia, the history would usually elude to some preceding symptoms such as palpitations, chest pain or shortness of breath to indicate a cardiac origin. In this context, an arrhythmogenic collapse would be a much less likely cause than a simple faint
33460
c
Cardiac arrhythmia
QuestionChoice
If this patient has been sat down on the tube for a prolonged period and had then stood up prior to collapsing, postural hypotension could be a possible explanation
33461
d
Postural hypotension
Concept
Chapter
# Summary
 
Syncope means a transient loss of consciousness and is a common emergency presentation. There are many causes with important differentials being reflex syncope, orthostatic hypotension and cardiac syncope. The term "blackouts" is commonly used to refer to a loss of consciousness, and includes differentials such as seizures. A thorough history (including a collateral if available) is important to help to differentiate the above, followed by examination including a lying-standing blood pressure. Initial investigations include an ECG, a blood glucose and consideration of a basic set of bloods to screen for abnormalities such as hyponatraemia that could trigger seizures. Emergency management encompasses ruling out serious causes, treating any injuries sustained during the episode and referral on for specialist investigations and management as appropriate.

# Definition 

Blackouts refer to episodes of transient loss of consciousness, which occur for a variety of reasons. Syncope refers to a transient loss of consciousness secondary to cerebral hypoperfusion, with syncopal presentations making up the majority of cases of blackouts.
 
# Epidemiology 
  
Blackouts are common, with an estimated 50% of the population experiencing at least one in their lifetime. 3% of emergency department presentations and 1% of hospital admissions in the UK are due to blackouts.
 
# Aetiology
 
**Causes of cardiac syncope:**

- Structural
       - Acute myocardial infarction 
       -  Aortic stenosis 
       -  Ischaemic cardiomyopathy
       -  Hypertrophic obstructive cardiomyopathy
       -  Cardiac tamponade
- Electrical 
       - Tachyarrhythmias e.g. superventricular tachycarcia (SVT), ventricular tachycardia (VT), ventricular fibrillation (VF)
       - Bradyarrhythmias e.g. sick sinus syndrome, heart block
       - Inherited channelopathies e.g. Brugada syndrome

**Causes of reflex syncope:**
 
 - Vasovagal syncope ("fainting")
 - Situational syncope e.g. following defecation, post-exercise, or straining to pass urine
 - Carotid sinus syndrome - occurs due to hypersensitivity of the carotid sinus baroreceptor

**Other causes of syncope:**
 
 - Orthostatic hypotension
 - Pulmonary embolism
 - Occult haemorrhage e.g. subarachnoid haemorrhage, GI bleeding, ruptured aortic aneurysm
 - Head trauma
 - Hypoglycaemia

 **Non-syncopal causes of blackouts:**
 
 - Seizures
 - Psychogenic pseudosyncope
 - Psychogenic non-epileptic seizures

# Symptoms and Signs
 
When taking a history and examining a patient after a blackout, there are several additional symptoms and signs to elicit that can help identify the likely cause. If the blackout was witnessed, take a collateral history also. 

**Questions to ask about before the blackout:**

- What were they doing/any triggers?
    - Exertional syncope (cardiac)
    - After exercise (vasovagal/orthostatic hypotension)
    - Head movements/pressure on neck (carotid sinus syndrome)
    - Prolonged standing (orthostatic hypotension)
    - Pain (vasovagal)
    - Repeated episodes after defecation/micturition/swallowing/coughing (situational syncope)
    - After a meal (vasovagal or orthostatic hypotension)
- Prodromal symptoms?
    - Feeling warm/hot, sweating, nausea (vasovagal)
    - Déjà vu or jamais vu (epilepsy)
- Intercurrent illness?
    - e.g. diarrhoea and vomiting leading to dehydration and hypotension
- Associated symptoms?
    - Palpitations/chest pain/shortness of breath (cardiac/PE)
    - Headache (subarachnoid haemorrhage)
    - Visual disturbance (if worse on standing may be orthostatic hypotension/vasovagal)
    - Lightheadedness (orthostatic hypotension/vasovagal)
        
**Questions to ask about during the blackout:**
 
- Any protective measures taken?
    -  e.g. hands outstretched to break fall 
    - It can be difficult to ascertain whether the patient lost consciousness
    - If protective measures were observed may be a fall rather than a blackout
    - Patients having a vasovagal may lower themselves to the floor
- Tongue biting?
    - Lateral tongue typical in epilepsy
    - Tip of tongue typical in vasovagal
- Incontinence of bowels or bladder? (epilepsy)
- Duration of loss of consciousness
    - Less than 30 seconds (suggests syncope)
    - Over 1 minute (suggests epilepsy)
    - Over 5 minutes (psychogenic causes more likely)
- Seizure activity observed?
    - Myoclonic jerks are common in vasovagal syncope
    - Prolonged limb jerking and abnormal posturing suggests a seizure
- Appearance during blackout e.g. pallor, eyes closed or open? 
 

**Questions to ask about after the blackout:**

- Any injuries sustained during the blackout?
       - Ask about site and severity
- Confusion or amnesia after conciousness regained?
       - If lasts minutes may indicate post-ictal state after a seizure
- Focal neurological signs (e.g. weakness down one side)

**Other important questions:**

- Any previous blackouts/similar events?
- Past medical history e.g. any heart disease?
- Medications (may contribute to orthostatic hypotension)
- Family history including sudden cardiac or unexplained death in young relatives
- Recreational drug and alcohol use (alcohol may exacerbate orthostatic hypotension)

**On examination:**

- Do a full set of observations including a lying standing blood pressure to assess for a postural drop
        - A fall in systolic blood pressure by 20mmHg or more or diastolic by 10mmHg or more, or a fall in the systolic to <90mmHg with symptoms indicates orthostatic hypotension
- Full systems examination focusing on the heart (e.g. any murmurs or abnormalities of the pulse?)
- Neurological examination including cognitive function (may be abnormal in the post-ictal state)
 
# Investigations
 
Initial investigations as follows should be carried out in the emergency setting; patients should also be referred for further specialist investigations (e.g. EEG for epilepsy, Holter monitoring for suspected arrhythmias) as appropriate.

- **Blood glucose** for hypoglycaemia
- **ECG** looking for arrhythmias, ischaemic changes or evidence of structural abnormalities (e.g. left ventricular hypertrophy in severe aortic stenosis)
- **Blood tests** looking for electrolyte abnormalities that could trigger seizures or arrhythmias, anaemia in haemorrhage, raised inflammatory markers in intercurrent illness, AKI in dehydration
- **Transthoracic Echocardiography** should be done in suspected structural heart disease (e.g. aortic stenosis)
- **24 hour ambulatory blood pressure monitoring** with an activity diary may be useful to assess for e.g. post-prandial hypotension
 
# Management
 
- Specific emergency management may be required for any serious cause identified (e.g. head injury, ruptured aortic aneurysm).
- Investigate for and treat any injuries resulting from the collapse and provide analgesia.
- Some patients can be discharged with reassurance and advice e.g. uncomplicated vasovagal episode, situational syncope.
- Patients with suspected epilepsy should be referred to a first fit clinic.
- Patients with suspected psychogenic causes of blackouts should also be referred for neurology assessment as these can be difficult to differentiate from epilepsy
- Patients with suspected cardiac syncope (e.g. abnormal ECG, exercise-induced syncope, heart murmur, heart failure, new/unexplained breathlessness or family history of sudden cardiac death in the young/inherited cardiac condition) should be referred for specialist review within 24 hours.
- Consider urgent referral for cardiovascular review in all patients over 65 with syncope and no prodromal symptoms.
- All patients with syncope of unclear cause should be referred for specialist cardiovascular review (with urgency based on the clinical picture)

 **Driving advice for patients with syncope:**

- Patients with unexplained syncope must inform the DVLA and their licence will be revoked for 6 months (12 months if Group 2) 
- Patients with a vasovagal whilst standing can drive and need not inform the DVLA if they are Group 1 drivers (Group 2 drivers must not drive and should inform the DVLA)
- Patients with cardiac syncope must not drive and should inform the DVLA - group 1 drivers may be allowed to drive after 4 weeks if a cause is identified and treated
- Full guidance including for seizures can be found in the references section
 
# NICE Guidelines
 
[NICE CKS Guidance on Blackouts](https://cks.nice.org.uk/topics/blackouts/)

[NICE: Transient loss of consciousness ('blackouts') in over 16s](https://www.nice.org.uk/guidance/cg109)
 
# References 
 
[DVLA guidance on transient loss of consciousness](https://www.gov.uk/guidance/neurological-disorders-assessing-fitness-to-drive#transient-loss-of-consciousness-blackouts--or-lostaltered-awareness)
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Syncope
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Neurology
Video
Concept
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Syncope
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Generalised seizures
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A 23-year-old female experiences rapid "closing in" of her vision and then collapses when travelling as a standing passenger on a busy tube train. Passers-by witness convulsing movements of her arms and legs for approximately 15 seconds following the collapse. She regains consciousness immediately after and has a Glasgow Coma Scale (GCS) of 15.

What is the most likely diagnosis?
a