Cavernous Sinus Thrombosis

Thrombosis of the cavernous sinus, usually septic, from spread of infection of the face (central danger triangle: nose, upper lip, medial canthus), sinuses (sphenoid and ethmoid), teeth, ear or orbit through valveless veins. Aseptic types occur with trauma, malignancy, thrombophilia and dehydration.

• Organisms: Staphylococcus aureus (70 percent, includes methicillin resistant strains), streptococci, anaerobes, Gram negative bacilli, fungi (Aspergillus, Mucorales) in diabetic ketoacidosis.
• The sinus contains cranial nerves III, IV, V1, V2 and VI, the internal carotid artery and sympathetic fibres, producing characteristic signs. Bilateral spread occurs within 24 to 48 hours through the intercavernous sinuses.
• Mortality is 20 to 30 percent with treatment (previously near 100 percent), with permanent cranial nerve deficit or blindness in many survivors.

• Acute: high fever, rigors, severe headache (frontal or retro orbital), nausea.
• Ocular: unilateral then bilateral proptosis, chemosis, periorbital oedema, ptosis, ophthalmoplegia (sixth nerve first, then third and fourth), dilated or fixed pupil, loss of corneal sensation, papilloedema, retinal haemorrhages, reduced vision.
• Sensory loss in the V1 and V2 distribution; Horner syndrome in the early phase.
• Meningism, drowsiness, seizures, and cranial nerve deficits indicating intracranial spread; septic emboli to lungs.
• Facial skin infection (furuncle, pustule) or sinusitis often precedes by days.

• Clinical diagnosis with urgent imaging: MRI with contrast and MR venography (filling defect, enlarged heterogeneous sinus, bulging lateral wall) or CT venography with contrast.
• Blood cultures (before antibiotics, at least 2 sets), full count, CRP, coagulation screen, glucose, ketones, HIV test, thrombophilia screen if no source.
• Lumbar puncture only after imaging if meningitis suspected (cells, protein, culture, glucose).
• ENT examination, sinus and dental imaging; swabs of source.
• Differential: orbital cellulitis, carotid cavernous fistula, orbital apex syndrome, idiopathic cavernous sinus inflammation, cavernous sinus tumour.

• Admission to a high dependency unit with immediate intravenous antibiotics after blood cultures:
  • Ceftriaxone 2 g IV every 12 hours plus vancomycin 15 to 20 mg/kg IV every 8 to 12 hours (trough 15 to 20 mg/L) plus metronidazole 500 mg IV every 8 hours.
  • Continue for at least 3 to 4 weeks IV (up to 6 weeks if intracranial extension), adjusted to cultures.
  • Fungal: liposomal amphotericin B 5 mg/kg daily, surgical debridement.
• Anticoagulation: therapeutic enoxaparin 1 mg/kg subcutaneously twice daily or unfractionated heparin infusion (activated partial thromboplastin time 1.5 to 2.5 times control) once no haemorrhage on imaging, then warfarin (INR 2 to 3) or a direct oral anticoagulant for 3 to 6 months. Evidence supports reduced mortality and morbidity with early anticoagulation.
• Corticosteroids: dexamethasone 0.15 mg/kg IV every 6 hours (adult 10 mg then 4 mg every 6 hours) can reduce cranial nerve damage and is essential if pituitary or adrenal insufficiency follows.
• Source control: drainage of sinuses, abscess and dental sources; control of diabetes.
• Neurosurgical care for hydrocephalus, abscess, raised intracranial pressure; seizure control with levetiracetam 500 mg to 1 g IV or orally twice daily.
• Monitor cranial nerve function and vision daily, pituitary function after recovery (hypopituitarism in up to 20 percent).