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Cavernous sinus thrombosis

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cavernous sinus thrombosis diagnosis management guideline

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cavernous sinus thrombosis MRI MR venogram cavernous sinus ophthalmic vein

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PMID: 39312001

Cavernous sinus thrombosis (CST)

Cavernous sinus thrombosis is a rare, life-threatening clot in the cavernous sinus, a venous channel at the skull base. It is usually septic, caused by spread of infection from the face, orbit, teeth, or paranasal sinuses, especially ethmoid or sphenoid sinusitis. It requires emergency hospital treatment.

Clinical features

Typical presentation is an acute infectious illness with:
  • Fever and severe retro-orbital or frontal headache
  • Painful periorbital edema, chemosis, and proptosis
  • Ptosis and impaired eye movements causing diplopia or complete ophthalmoplegia
  • Reduced corneal sensation or facial numbness in the ophthalmic division of trigeminal nerve
  • Visual loss, papilledema, or retinal venous congestion
  • Often progressive bilateral ocular signs, because the two cavernous sinuses communicate
  • Confusion, meningism, reduced consciousness, or seizures in severe disease
Cranial nerves III, IV, VI, V1, and V2 may be affected. Abducens nerve palsy is often an early sign because CN VI runs centrally through the sinus.

Diagnosis

Do not delay treatment while waiting for confirmation.
  • Obtain blood cultures before antibiotics if this does not cause delay.
  • Check CBC, inflammatory markers, renal/liver function, coagulation studies, and cultures from any suspected source.
  • Contrast-enhanced MRI with MR venography is preferred. It may demonstrate lack of flow or a filling defect in the cavernous sinus.
  • Contrast CT with CT venography is an alternative, and also helps identify sinus, orbital, or dental infection.
  • Assess for meningitis, cerebral infarction, abscess, and other intracranial extension as indicated.
Scott-Brown's Otorhinolaryngology describes MRI/MR venography as particularly sensitive, with absent flow in the thrombosed sinus; contrast CT can show corresponding filling defects (p. 4344-4347).

Management

This is an emergency involving ENT, ophthalmology, infectious diseases, neurology/neurosurgery, and radiology.
  1. Immediate IV broad-spectrum antibiotics, then tailor to cultures. Empiric therapy must cover Staphylococcus aureus including MRSA where relevant, streptococci, gram-negative organisms when indicated, and anaerobes if there is a dental/sinus source. Treatment is generally prolonged and guided by the infection source and clinical course.
  2. Control the source
    Urgent ENT or dental evaluation is needed. Drainage of infected paranasal sinuses, orbital abscess, or dental infection may be required.
  3. Consider therapeutic anticoagulation
    This is individualized after assessing for intracranial hemorrhage and other bleeding risks. A 2025 systematic review and individual-patient meta-analysis of sinusitis-associated adult CST found lower mortality with anticoagulation, 3.3% versus 18%, but the evidence came from observational case-level data and does not replace case-specific specialist judgment (Akarapas et al., 2025, PMID 39312001). Heparin was the most commonly used initial agent in that review.
  4. Steroids are not routine
    They may be considered selectively, for example for significant inflammatory orbital compression or adrenal insufficiency, but only with specialist direction and adequate antimicrobial treatment.
  5. Support and monitor
    Frequent neurologic and visual assessment, eye protection for exposure keratopathy, fluid/electrolyte management, and repeat imaging if deterioration occurs.

Key distinction from orbital cellulitis

CST should be suspected when presumed orbital cellulitis has cranial-nerve palsies, bilateral eye involvement, vision compromise, severe headache, mental-status change, or rapid progression. The MSD clinical review similarly highlights these distinguishing features and recommends MRI or CT venography.

Prognosis

Even with treatment, CST can cause blindness, persistent ocular motor palsies, stroke, meningitis, pituitary dysfunction, or death. Early recognition, IV antimicrobials, source control, and multidisciplinary care have substantially improved outcomes.
Urgent action: Fever with a severe headache plus a swollen/protruding eye, double vision, inability to move an eye, facial numbness, or altered consciousness warrants immediate emergency-department assessment.
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