Related Subjects:
|Transient Loss of Consciousness
|Vasovagal Syncope
|Syncope
|Aortic Stenosis
|First Seizure
|Carotid Sinus Syncope
⚠️ Any sudden loss of consciousness without warning should be assumed to be due to a cardiac arrhythmia until proven otherwise. Transient loss of consciousness (TLOC) must be taken very seriously and assessed and investigated. 🚗 It can have implications for driving: patients must be advised to stop driving and inform the DVLA until a cause is established. See Driving advice topic.
📖 About
- 🧑⚕️ Common ED presentation, particularly in older adults.
- 🌓 Often described as “blackouts.”
- 🔍 Key to distinguish from seizure, TIA, or metabolic causes.
📝 Assessment
- History is key: Reconstruct the episode in detail; 👀 witness accounts invaluable (ask family/friends with consent).
- Before: 🧍 Position, activity, prodrome (💫 visual dimming, 🤢 nausea).
- During: Responsiveness, 💥 movements (jerks vs tonic–clonic), duration, colour, breathing.
- After: ⏱️ Time to recovery, 💤 confusion, headache, drowsiness.
🔎 Differentials
- 🩸 Vasovagal syncope: Triggered by standing, heat, meals, alcohol. Brief LOC, quick recovery. Minor jerks possible, incontinence rare.
- ❤️ Cardiac causes: Arrhythmia (brady/tachy), aortic stenosis, HOCM. Often exertional/no warning. May need ECG, echo, Holter/loop recorder, pacemaker.
- 💔 Silent MI / hypotension: Check ECG, troponin, echo.
- 🫁 Pulmonary embolism: Large PE can present with syncope. D-dimer ± CTPA.
- 🧠 Subarachnoid haemorrhage: Thunderclap headache + transient LOC. CT brain early.
- ⚡ Seizure: Lateral tongue bite 👅, incontinence, prolonged post-ictal drowsiness. Needs neuro referral, CT/MRI ± EEG.
- 👔 Carotid sinus syncope: Triggered by tight collars/head turning. Diagnose with carotid massage (caution!).
- 📉 Orthostatic hypotension: Drop in SBP >20 mmHg when standing. Common in elderly, worsened by 💊 diuretics, alpha-blockers, Parkinson’s meds.
- 🍭 Hypoglycaemia: Often in diabetics, Addison’s, or rarely insulinoma.
🧪 Investigations
- 🩸 Bloods: FBC, U&E, glucose, TFTs, bone profile.
- 📈 Cardiac: ECG, troponin, Holter (24–72h) or loop recorder, echo.
- 🫁 Thromboembolic: D-dimer ± CTPA if PE suspected.
- 🧠 Neurology: CT/MRI brain (SAH, seizure, structural cause). EEG if recurrent unexplained episodes.
- 🧬 Endocrine/metabolic: Glucose, cortisol (± Synacthen test if Addison’s suspected).
💊 Management
- 💊 Review meds: rationalise antihypertensives in frail, stop/reduce CCB, diuretics, alpha-blockers if contributory.
- 🚗 Driving advice: Stop until cause clarified; DVLA must be informed.
- Specific therapy:
- ❤️ Cardiac: Pacemaker (brady), ablation (tachy).
- 🧍 Vasovagal / orthostatic: Lifestyle (hydration 💧, slow posture changes). Fludrocortisone/midodrine if resistant.
- ⚡ Seizure: Anticonvulsants if recurrent/unprovoked. Neuro referral.
- 🚨 Acute causes: PE, MI, SAH → urgent specialist management.
💡 Clinical Pearl:
The most dangerous differential is arrhythmic cardiac syncope 🫀 — always exclude this first.
📚 Exam tip: “Sudden collapse, no prodrome, rapid recovery” → think cardiac syncope until proven otherwise.
