Related Subjects:
|Transient Loss of Consciousness
|Vasovagal Syncope
|Syncope
|Aortic Stenosis
|First Seizure
|Carotid Sinus Syncope
⚠️ Transient loss of consciousness (TLOC) must always be taken seriously.
🫀 A sudden collapse without prodrome, during exertion, or with structural heart disease should raise suspicion of cardiac syncope, which carries the highest mortality risk.
🚗 Patients should be advised not to drive until specialist assessment and to follow DVLA guidance once a diagnosis is made.
📖 About
- Common ED and GP presentation.
- Often described as “blackouts.”
- Defined as spontaneous loss of consciousness with complete recovery.
- Key aim: distinguish syncope from seizure, psychogenic events, metabolic causes, or TIA.
📝 Initial Assessment (NICE Core Requirements)
- Detailed history from patient and witness (if possible).
- Physical examination including cardiovascular and neurological exam.
- 12-lead ECG for all patients.
- Lying and standing BP if orthostatic hypotension suspected.
🔎 History Framework
- Before: Posture, exertion, triggers, prodrome (visual dimming, nausea, warmth).
- During: Duration, limb jerking (brief myoclonic jerks can occur in syncope), colour change, breathing pattern.
- After: Rapid recovery (syncope) vs prolonged confusion >5–10 min (suggests seizure).
- Red flags: Chest pain, palpitations, family history sudden death, exertional collapse.
🧠 Common Causes of TLOC
- 🩸 Reflex (vasovagal) syncope – commonest cause; trigger + prodrome + rapid recovery.
- 📉 Orthostatic hypotension – SBP drop ≥20 mmHg on standing.
- 🫀 Cardiac syncope – arrhythmia, structural heart disease (aortic stenosis, HOCM).
- ⚡ Epileptic seizure – lateral tongue bite, prolonged post-ictal state.
- 🫁 Pulmonary embolism – syncope with hypoxia or haemodynamic compromise.
- 🧠 Subarachnoid haemorrhage – thunderclap headache ± LOC.
- 🍭 Hypoglycaemia – particularly in insulin-treated diabetes.
- 👔 Carotid sinus hypersensitivity – older adults; diagnosed in specialist setting.
🧪 Investigations (NICE-Guided)
- 📈 ECG for all (mandatory).
- 🩸 Blood glucose if suspected.
- 🩸 Routine bloods only if clinically indicated (not mandatory for all).
- 🎧 Ambulatory ECG monitoring if arrhythmia suspected.
- 🫀 Echocardiography if structural heart disease suspected.
- 🧠 Neuroimaging and EEG only if seizure or neurological cause suspected (not routine).
🚨 High-Risk Features Requiring Urgent Cardiology Assessment
- Abnormal ECG.
- Heart failure or structural heart disease.
- Syncope during exertion.
- Family history sudden cardiac death.
- No warning and sudden collapse.
💊 Management
- Review medications (antihypertensives, diuretics, rate-limiting drugs).
- Hydration advice and counter-pressure manoeuvres for vasovagal syncope.
- Midodrine or fludrocortisone if recurrent orthostatic syncope.
- Pacemaker for symptomatic bradyarrhythmia.
- Ablation or anti-arrhythmic therapy if tachyarrhythmia confirmed.
- Specialist referral for seizure or neurological causes.
🚗 Driving (UK – DVLA Principles)
- Patients must stop driving until cause established.
- Cardiac syncope usually requires DVLA notification.
- Vasovagal syncope with clear trigger may not require long restriction once diagnosed.
- Professional drivers (Group 2) have stricter rules.
💡 Clinical Pearl:
Sudden collapse without prodrome, especially with abnormal ECG, is cardiac until proven otherwise.
Reflex syncope is common — but arrhythmic syncope is the one that kills.
📚 NICE Reference
- NICE CG109 – Transient loss of consciousness (blackouts) in over 16s.
