Carotid sinus hypersensitivity (CSH) = exaggerated vagal response to external pressure on the carotid sinus.
Mostly affects elderly patients 🧓, causing reflex bradycardia/asystole and hypotension → syncope or unexplained falls.
Rare overall (<1% of transient loss of consciousness) but up to 50% of unexplained elderly syncope cases.

⚙️ Aetiology

Abnormally sensitive carotid baroreceptors misinterpret mild external pressure as marked hypertension → exaggerated vagal reflex.
Triggers: tight collars 👔, head turning ↔️, shaving, neck pressure.
Mechanism:
- Cardioinhibitory: Pause ≥3 sec (asystole/bradycardia).
- Vasodepressor: SBP fall ≥50 mmHg.
- Mixed type: Both present.

🩺 Clinical Presentation

⚡ Syncope/near-syncope triggered by neck pressure.
🧓 Unexplained falls in elderly patients.
💓 Symptoms reproducible with CSM (in a monitored setting).

🔍 Differential Diagnosis

Vasovagal syncope
Cardiac arrhythmias (e.g. heart block, sick sinus)
Orthostatic hypotension

🧪 Investigations

Carotid Sinus Massage (CSM): Performed supine with ECG + BP monitoring, resus equipment + atropine ready. Positive = pause ≥3 sec (cardioinhibitory) OR BP drop ≥50 mmHg (vasodepressor).
🖼️ Carotid ultrasound BEFORE CSM to exclude severe stenosis/plaques (embolism risk).
ECG, Holter, tilt-table may help exclude other causes.

🛠️ Management

Immediate: Supine position + leg elevation → improve cerebral perfusion.
Preventive: Avoid tight collars, sudden head turning, external neck pressure.
Cardioinhibitory: Dual-chamber pacemaker 💓 if recurrent symptomatic episodes.
Vasodepressor: Ensure hydration, review antihypertensives; fludrocortisone or midodrine may help selected patients.
Follow-up: Ongoing BP/HR monitoring; fall prevention advice in elderly.

💡 Clinical Pearl: Think of CSH in an elderly patient with recurrent unexplained falls, no prodrome, and normal cardiac workup.

📚 Case Example

👨 An 80-year-old man presents with recurrent unexplained falls 🧓. No prodrome, no chest pain. ECG normal. During CSM under monitoring, he develops a 4-second sinus pause ⚡ with syncope. ✅ Diagnosis: Carotid sinus hypersensitivity (cardioinhibitory type). 🛠️ Management: Pacemaker implanted 💓 → no further episodes.

📎 References

BNF – pharmacological reference
European Society of Cardiology Guidelines on Syncope (2018)
Kenny RA et al. Carotid sinus syndrome: a common cause of unexplained falls in the elderly. Heart. 2001.

📅 Revisions

Last updated: [Insert Date]

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Carotid Sinus Syncope

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