Syncope and TLOC (non-traumatic)

Overview

Definitions

Syncope is defined as a transient loss of consciousness due to cerebral hypoperfusion, characterised by a rapid onset, short duration, and spontaneous complete recovery.

Transient loss of consciousness (TLOC) is defined as a state of real or apparent LOC with loss of awareness, characterised by amnesia for the period of unconsciousness, abnormal motor control, loss of responsiveness and a short duration.

There are 2 main groups of TLOC:

• TLOC due to head trauma  - please see advice on Head Injury (CKS) and Concussion (Remedy)
• Non-traumatic TLOC

The following page deals only with non-traumatic TLOC. (1)

(1) 2018 ESC Guidelines for the diagnosis and management of syncope

Assessment

Many patients with TLOC present in ED where there is immediate access to ECG, bloods and other investigations which should exclude urgent or life threatening conditions.

Some patients will present in primary care, either following admission and discharge or having not presented to ED.

In either event a diagnosis should be established based on history, examination and investigations.

DVLA

Please check the DVLA guidelines Assessing Fitness to Drive: a guide for medical professionals and more specifically the guidelines relating to Transient Loss of Consciousness for advice on driving.

Children

Please refer to the Syncope in Children page for advice.

Who to Refer

Patients with the following diagnoses with normal examination and no red flags can often be managed in primary care and do not usually need referral (see the sections below for further advice):

• Vasovagal syncope
• Situational reflex syncope 
• Orthostatic Hypotension

Further investigations and referral should be considered for patients who do not fulfil the criteria for the above diagnoses as symptoms may have one of the following causes:

• Cardiac syncope (arryhthmic or structural)
• Syncope in patients with comorbidity or frailty
• Neurological causes (cerebrovascular disease, epilepsy, coma)
• Metabolic causes (hypoglycaemia, hypoxia, hyperventilation, hypocapnia)
• Other (psychogenic pseudocoma, intoxication, cataplexy) 

Vasovagal and Reflex Syncope

A vasovagal episode is highly probable if syncope is precipitated by pain, fear, or standing and is associated with typical prodrome (pallor, sweating and/or nausea).

Situational reflex syncope is highly probable if syncope occurs during or immediately after a specific trigger (e.g. micturition, swallow, defaecation, cough, sneeze, post exercise, laughing).

In both cases there is often a history of recurrent syncope, in particular occurring before the age of 40 years.

Investigation

If examination is normal and no red flags then further investigation is not normally required.

Do an ecg if first episode or symptoms are not typical.

Treatment

Explanation of the diagnosis, reassurance, avoidance of triggers are generally all that is required.

Orthostatic Hypotension

Orthostatic Hypotension (OH) can usually be confirmed when syncope occurs while standing and there is concomitant hypotension.

Typical features situation that trigger OH include:

• while or after standing
• after prolonged standing
• standing after exertion
• post - prandial
• temporal relationship with start or changes of vasopressive drugs or diuretics
• presence of autonomic neuropathy or parkinsonism

Investigation

Measure supine BP and pulse and then repeat while standing for 3 minutes. OH is confirmed when there is one of more of the following that reproduces spontaneous symptoms:

• fall in systolic BP from baseline of 20mmHg or more
• fall in diastolic BP of 10mmHg or more
• decrease in systolic BP to less than 90mmHg

Undertake an ecg if first episode or symptoms not typical.

Treatment

Explanation of diagnosis, reassurance and avoidance/cessation of triggers.

Ensure adequate hydration and salt intake.

Consider referral if autonomic dysfunction or underlying neurological disease is suspected.

Cardiac Syncope

If cardiac syncope is suspected, then a cardiovascular examination and 12 lead ecg should be performed as soon as possible after the event.

Patients with persistent symptoms, concerning ecg changes or other red flags should be transferred directly to the Emergency Department by ambulance for early intervention or monitoring.

See Arrhythmia page for details or see red flags section below. 

Patients who are otherwise stable can be referred to cardiology via eRS (see services section below). Alternatively, cardiology advice and guidance can be obtained (please include ecg).

Neurological evaluation

If epilepsy or other neurological disease is suspected, then seek advice from a neurologist or refer as appropriate:

Neurology Advice and Guidance/ Hot Clinic

First Seizure Clinic

Features that may suggest a seizure rather than syncope include:

• Lack of Triggers - triggers are rare in epilepsy but common in syncope. Flashing lights can be a trigger for epilepsy.
• Aura - specific for each patient e.g. deja vu, epigastric aura (rising sensation in abdomen), olfactory aura (unusual or unpleasant smell)
• Myoclonus - muscle jerking can occur in syncope so is not diagnostic of epilepsy. In epilepsy amplitude is 20-100 (tends to slower in syncope), onset coincides with LOC (tends to start after LOC in syncope). Movements are generally symmetrical, synchronus. Chewing or lip smacking can be prolonged.
• Tongue biting - tends to be on one side of the tongue in epilepsy (rare in syncope)
• Duration - restoration of consciousness may take several minutes (syncope usually shorter duration- 10 to 30 seconds)
• Confusion afterwards - can last several minutes after seizure (tends to only last a few seconds in syncope).

Features that are less useful in differentiation between seizure and syncope:

• Incontinence - common during seizure but not uncommon during syncope.
• Fatigue and sleep after event - common after both
• Eyes open during LOC - Nearly always during a seizure but also frequently during syncope
• Blue face - Fairly common during seizure but can also be a rare feature of syncope.

Red Flags

High Risk features associated with syncope that should prompt immediate assessment:

• New onset chest discomfort
• Breathlessness
• Abdominal pain
• Headache
• History of severe heart disease (structural, coronary artery disease, heart failure)
• Unexplained systolic BP <90
• Suspicion of GI bleed
• Persistent bradycardia (<40)
• Undiagnosed systolic murmur
• High risk ecg changes (discuss with on call cardiology team if help with interpretation required)
• Exercise induced syncope

Other features that may be concerning particularly if associated with structural heart disease or ecg changes:

• No warning symptoms or short prodrome (<10 seconds) 
• Family history of sudden cardiac death at a young age
• Syncope in sitting position

What to do before referral

If patient is stable and no red flags but referral for further investigation is indicated then undertake the following prior to referral:

• Detailed history of episode of syncope (including from witness if possible).
• Cardiovascular and neurological examination
• Supine and standing BP
• 12 lead ECG (essential)
• Bloods (including FBC, UE, lipids, HbA1c,TFT)
• Echocardiogram (optional) - consider requesting echocardiography at time of referral if strong suspicion of cardiac disease e.g. positive family history, audible murmur or abnormal ECG. (if structural heart disease suspected). 

Services

Cardiology Advice and Guidance

UHBW and NBT offer advice and guidance (please include ecg) via eRS

Bristol Heart Institute

The BHI offers several services on eRS that may be appropriate for referral of patients with syncope. They include:

• Cardiac monitoring clinic  RAS
• Electrophysiology and complex arrhythmia clinic
• Inherited cardiac conditions clinic - for patients with positive family history of inherited cardiac conditions.

NBT

NBT has a comprehensive cardiac service and will accept referrals via eRS:

• Cardiac rhythm analysis via cardiology monitoring RAS
• General cardiology clinic

Weston

Weston is part of UHBW but also has cardiology clinics available via eRS:

• General cardiology

Falls/Syncope in older or frail adults

For older patients who do not have a suspected cardiac cause of syncope or where a cardiac cause has been excluded then consider referral to the care of the elderly falls pathway.

Resources

(1) 2018 ESC Guidelines for the diagnosis and management of syncope

(2) Blackouts and syncope | Health topics A to Z | CKS | NICE

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