CBL: Cavernous Sinus Venous Thrombosis

Painful ophthalmoplegia with fever/proptosis — suspect cavernous sinus pathology.

Topic: Neuro-ophthalmology / Neurovascular Level: Student–Resident

Learning Objectives

  • Review cavernous sinus anatomy: a dural venous sinus containing CN III, IV, V1, V2, VI and the internal carotid artery with sympathetic plexus (note: CN II runs in the optic canal, not within the cavernous sinus).
  • Recognize that cavernous sinus pathology presents with headache/eye pain and ophthalmoplegia.
  • Understand that cavernous sinus thrombosis (CST) can be fatal and requires urgent IV antibiotics and anticoagulation.

Vignette

A 65-year-old woman develops severe sharp retro-orbital pain (right), fever, blurred vision, proptosis, and inability to move the eye to the right with horizontal diplopia. She does not usually have headaches. Sent to the ER. Meds: omeprazole, metformin; no drug allergies. PMH: diabetes, osteoarthritis, GERD. Nonsmoker, nondrinker; office administrator. Family history: father—prostate cancer; mother—stroke at 81. ROS notable for diplopia and eye pain; otherwise negative.

Examination

Distressed, slightly overweight; holding right eye. T 99.3°F, HR 86, BP 144/84. Cardiac/carotid exams normal. Right eye proptosis; sluggish right pupillary light response; mild right ptosis. Incomplete right eye abduction (CN VI palsy). Decreased pinprick in right V1 (forehead). Facial expression normal; hearing grossly normal; palate/shoulder/tongue movements normal. Limb strength/reflexes/sensation normal; toes downgoing; coordination, Romberg, and gait normal.

Localization & Neuroanatomy

Proptosis, painful ophthalmoplegia, decreased V1 sensation, ptosis with sluggish pupil, and VI palsy co-localize to the right cavernous sinus. Cranial nerves III, IV, V1, V2 lie in the lateral wall; VI and the internal carotid artery (with sympathetic plexus) traverse the sinus proper.

Diagnosis

Cavernous sinus disorders often cause eye pain, diplopia, proptosis, visual disturbance, ptosis, and pupillary abnormalities. Etiologies include venous thrombosis (most common), carotid aneurysm, infection, and neoplasm.

Workup typically includes MRI brain/orbits with contrast and MRV/MRA of the cavernous sinus/carotid; inflammatory labs and blood cultures (ESR, CRP, WBC) support infectious CST. CST frequently arises from contiguous infection (sphenoid/ethmoid sinuses, dental/nasal sources), commonly due to Staphylococcus aureus, with venous congestion predisposing to thrombosis. Carotid compromise can rarely produce ischemic stroke.

Treatment

Emergency management: Broad-spectrum IV antibiotics (covering staphylococci/streptococci/anaerobes) plus anticoagulation (e.g., low-molecular-weight heparin) are commonly employed. Consider ENT/dental source control. Surgical intervention is reserved for cases needing biopsy/debridement or refractory infectious/humoral etiologies.

Teaching Points

  • Painful ophthalmoplegia with proptosis and V1 numbness localizes to the cavernous sinus.
  • Most CST cases are septic from paranasal or dental sources; obtain imaging and blood cultures promptly.
  • Start IV antibiotics and anticoagulation early—CST can be rapidly fatal without treatment.

Question 1

Which cranial nerves course through the cavernous sinus region?

  • A. I, II, III, IV, V, VI
  • B. II, III, IV, V, VI
  • C. III, IV, V1, V2, VI
  • D. II, III, VI, IX, X

Question 2

Which conditions commonly affect the cavernous sinus?

  • A. Infection
  • B. Neoplasm
  • C. Inflammation
  • D. Venous thrombosis
  • E. Both A and D

Question 3

When CST is suspected, which initial therapy is recommended?

  • A. Aspirin
  • B. Trimethoprim–sulfamethoxazole (Bactrim) alone
  • C. Low-molecular-weight heparin and broad-spectrum IV antibiotics
  • D. Surgical debridement alone
  • E. Clinical observation

References

  1. Module adapted from provided teaching text on cavernous sinus thrombosis, emphasizing localization, imaging, and emergent management.