What is a cavernous sinus thrombosis?

Cavernous Sinus Thrombosis

Cavernous sinus thrombosis (CST) is a serious thrombophlebitic condition of the cavernous sinuses that carries significant morbidity and mortality, with less than half of patients recovering completely and a mortality rate of approximately 30%, despite modern treatment. 1

Clinical Presentation

CST typically presents with the following characteristic features:

• Cranial nerve involvement:

  • Cranial nerve VI (abducens) palsy - most commonly affected, resulting in lateral rectus palsy and limited lateral gaze
  • May also affect cranial nerves III (oculomotor), IV (trochlear), and V (trigeminal) 1

• Ocular manifestations:

  • Periorbital edema
  • Chemosis (conjunctival swelling)
  • Proptosis (bulging of the eye)
  • Ptosis (drooping eyelid)
  • Ophthalmoplegia (restricted eye movement) 2

• Systemic symptoms:

  • Fever (present in nearly all cases)
  • Headache
  • Altered mental status
  • Seizures
  • Signs of increased intracranial pressure 1

• Progression pattern: Bilateral involvement often occurs within 48 hours of initial unilateral signs 1

Etiology

The most common causes of CST include:

1. Infectious causes (septic CST):

   • Sinusitis (particularly sphenoid and ethmoid)
   • Facial infections in the middle third of the face
   • Dental abscesses
   • Otitis media 3

2. Non-infectious causes:

   • Thrombophilia
   • Dehydration
   • Medications
   • Maxillofacial trauma or surgery 2

3. Common pathogens:

   • Staphylococcus aureus (most common)
   • Streptococcal species
   • Oral anaerobic species
   • Gram-negative bacilli 2

Diagnostic Evaluation

Imaging

• MRI with MR venography (MRV) is the preferred first-line imaging modality with the highest sensitivity, showing both thrombus and parenchymal changes 1

• CT with contrast shows the characteristic "empty delta" sign (lack of enhancement within the affected venous structure) 1

• Comparison of imaging modalities:

  • CT+CTV: Quick (5-10 min), readily available, fewer motion artifacts, usable with pacemakers/claustrophobia
  • MRI+MRV: Better visualization of venous systems, superior detection of early ischemic changes, no radiation exposure, better detection of cortical and deep venous thrombosis, superior detection of micro/macrobleed 1

Laboratory Testing

• Elevated inflammatory markers
• Blood cultures (positive in up to 70% of cases) 2

Management

Anticoagulation

• Initiate anticoagulation with either intravenous unfractionated heparin or subcutaneous low molecular weight heparin, even in the presence of hemorrhagic changes 1
• Consider non-heparin based anticoagulants if there is concern for heparin-induced thrombocytopenia 1
• Duration of anticoagulation based on underlying cause:
  • 3 months for transient risk factors
  • 6-12 months for idiopathic thrombosis or mild thrombophilia
  • Lifelong for high-risk thrombophilia, recurrent events, or antiphospholipid syndrome 1

Antimicrobial Therapy

• Initiate broad-spectrum antibiotics immediately to cover common pathogens (Staphylococcus aureus, Streptococcal species, oral anaerobes, and Gram-negative bacilli) 1
• Consider antifungal therapy if invasive fungal sinusitis is suspected (voriconazole preferred) 1

Surgical Management

• Functional endoscopic sinus surgery to drain the primary site of infection when sinusitis is the underlying cause 1
• Surgical debridement may be considered for invasive fungal sinusitis 1

Complications

• Hemorrhagic infarction (40% of cases)
• Hydrocephalus (10% of cases)
• Extension to other venous sinuses (lateral dural venous sinuses and superior sagittal sinus) 1

Follow-up

• Early follow-up CTV or MRV for patients with persistent or evolving symptoms despite medical treatment 1
• Follow-up CTV or MRV at 3-6 months after diagnosis to assess recanalization of the occluded cortical vein/sinuses in stable patients 1
• Close neurological monitoring during the acute phase 1

Prognosis

Despite modern treatment, CST carries significant morbidity and mortality:

• Less than half of patients recover completely
• Mortality rates of approximately 30% 1

This highlights the critical importance of early recognition and aggressive management of this condition to improve outcomes.