Cavernous sinus thrombosis/infection


Venous sinuses on either side of pituitary gland in which CN III, IV, V (V1 & V2) and VI, as well as ICA course through. Inferior to optic chiasm. Sinus drains venous blood from orbit and cortex, before draining to internal jugular vein. Additionally, the sinus drains facial and pterygoid plexus veins via the ophthalmic veins, thus infections of the nose and soft palate can spread to the cavernous sinus.

Figure taken from Radiopaedia

The “danger zone” or “triangle of danger”; use whichever you think sounds more dramatic. Taken from Wikipedia.

Thrombosis is usually secondary to:

  • Thrombophilia
  • Oral contraceptive/pregnancy/puerperium
  • Trauma
  • Malignancy
  • Infection




  • Headache – normally subacute, but can be thunderclap
  • Diplopia
  • Orbital chemosis, peri-orbital swelling
  • Reduced sensation on face
  • Seizures

On examination

  • Variable ophthalmoplegia
    • CN VI palsy most common – possibly because it sits in the middle of the cavernous sinus and not in wall.
    • Remember CN III, IV and VI all move through the cavernous sinus
  • Mydriasis (pupil dilation)
  • Ptosis eventually bilaterally
  • Chemosis, proptosis, again, eventually bilaterally
  • Loss of sensation or pain in V1/V2
  • Fever, as infection is often the cause of thrombosis


Key differential is orbital cellulitis

MRI with contrast is the imaging method of choice

T1 MRI + contrast: Left cavernous sinus thrombosis. Taken from Radiopaedia.

Lumbar puncture

  • 75% have evidence of inflammatory process:
  • High WBC (mostly neutrophils), normal glucose, elevated protein, culture negative
  • 33% have identical findings to bacterial meningitis
  • Useful in differentiating from orbital cellulitis


  • Antibiotics – high dose IV for 2-3 weeks, depending on source
    • Something to cover MRSA and MSSA +
    • + Ceftriaxone
    • + Gram negative cover if indicated
  • Heparinisation/anti-coagulation