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🧠 Cavernous Sinus Thrombosis (CST) is a rare but life-threatening condition caused by a thrombus in the cavernous sinus.
It endangers vision and cranial nerve function due to close anatomical relationships. 🚨
📌 About
- Definition: Thrombosis of the cavernous sinus, a venous plexus at the skull base that drains blood from the brain and orbit.
- Key Structures: Contains CN III, IV, V1, V2, VI and internal carotid artery → explains the severe neurological risks.
- Mortality/Morbidity: Untreated CST carries a very high mortality; prompt recognition saves lives.
⚠️ Aetiology
- Source of Infection: Spread from paranasal sinuses (esp. sphenoid/ethmoid), face (“danger triangle”), dental abscesses, or orbital cellulitis.
- Common Pathogens:
- 🦠 Staphylococcus aureus → most common, aggressive.
- 🦠 Streptococcus spp. → sinus-related CST.
- 🍄 Gram-negatives & fungi → esp. in immunocompromised patients.
- Mechanism: Infection spreads retrogradely via valveless facial/ophthalmic veins → endothelial injury → clot formation.
🎯 Risk Factors
- Chronic sinusitis or dental/orbital infection.
- Immune compromise (HIV, diabetes, steroids, chemotherapy).
- IV drug use.
- Hypercoagulable states (pregnancy, OCP use, thrombophilia).
🩺 Clinical Features
- Ophthalmoplegia: Diplopia from CN III, IV, VI palsies (VI most vulnerable → lateral rectus weakness).
- Trigeminal Involvement: Sensory loss in V1 ± V2 distribution.
- Eye Signs: Proptosis, chemosis, painful red eye, decreased visual acuity.
- Headache: Severe, often periorbital or frontal.
- Systemic: Fever, malaise, sepsis picture.
- Advanced: Raised ICP (nausea, vomiting, altered GCS) and seizures.
🔬 Investigations
- Bloods: ↑ WCC, ↑ CRP/ESR, blood cultures (guide therapy).
- Imaging:
- 🧲 MRI + MRV = gold standard (shows thrombus and venous flow obstruction).
- MRI may show oedema or early abscess formation.
- Ophthalmology exam: Assess vision, pupils, eye movements.
- Thrombophilia screen: If no obvious infection source.
🧾 Differentials
- Meningitis → fever, headache, neck stiffness (but no proptosis/ophthalmoplegia).
- Orbital Cellulitis → proptosis but no CN palsies.
- Intracranial Abscess or Tumour → mass effect, slower progression.
💊 Management
- Antibiotics: Start immediately (empirical broad-spectrum).
- Vancomycin + 3rd gen cephalosporin (e.g. ceftriaxone) + metronidazole.
- Tailor to culture/sensitivity results.
- Anticoagulation: Controversial but often used to prevent thrombus propagation (risk–benefit must be weighed).
- Supportive Care:
- ICP management (head up, fluids, mannitol if needed).
- Analgesia and antipyretics.
- Surgical/ENT: Drain primary infection source (e.g. sinus surgery, dental abscess drainage).
- Follow-Up: Repeat MRI/MRV to monitor clot resolution.
📉 Prognosis
- Improved with early antibiotics + supportive care.
- Long-term sequelae may include cranial nerve palsies, visual loss, or seizures.
- Mortality has fallen but remains significant if diagnosis is delayed.
