Cavernous sinus thrombosis (CST) is a rare but life-threatening condition caused by a blood clot in the cavernous sinus, a major vein located near the base of the brain. The cavernous sinus drains blood from the face and brain, and because it is near critical structures such as the carotid artery and cranial nerves, CST requires immediate medical attention to prevent serious complications or death.
Anatomy of the Cavernous Sinus
The cavernous sinuses are paired venous structures located behind the eyes, on either side of the pituitary gland. Key anatomical features housed in the cavernous sinus include:
- Cranial nerves: Trigeminal nerve (V) with its ophthalmic (V1) and maxillary (V2) divisions, oculomotor nerve (III), trochlear nerve (IV), abducens nerve (VI), and others.
- Internal carotid artery: This artery supplies blood to the brain and passes through the cavernous sinus.
- Venous connections: Blood from the sphenoparietal sinus, ophthalmic veins, and facial veins drains into the cavernous sinus, which empties into the internal jugular vein via the superior and inferior petrosal sinuses.
Due to its complex network of veins and nerves, any abnormality in the cavernous sinus can cause significant neurological and vascular problems.
Causes of Cavernous Sinus Thrombosis
CST is most commonly caused by infections in the head and face, especially those draining into the cavernous sinus, such as:
- Sinusitis (especially ethmoid or sphenoid)
- Facial infections (furuncles, dental abscesses, orbital cellulitis)
- Ear infections (otitis media)
- Injuries or surgeries involving the sinuses, face, or head
Infections can spread to the cavernous sinus through venous channels, leading to inflammation of the vessel wall (phlebitis) and clot formation. Less commonly, non-infectious causes include:
- Hypercoagulable conditions (hereditary clotting disorders)
- Head injuries
- Cancer affecting the cavernous sinus or nearby tissues
Pathophysiology
When a thrombus forms in the cavernous sinus, it obstructs normal venous drainage, causing congestion and reduced blood flow. This can result in tissue ischemia and increased intracranial pressure. The infection can spread to other sinuses, leading to systemic thrombosis or sepsis.
CST often leads to neurological impairments because the cavernous sinus is surrounded by multiple cranial nerves. Oculomotor dysfunction is common, leading to diplopia (double vision) and ophthalmoplegia (paralysis or weakness of eye muscles). If untreated, CST can cause meningitis, stroke, or brain abscesses.
Clinical Presentation
CST symptoms typically develop quickly and include:
- Severe headache: Often the first and most prominent symptom, localized around the forehead or behind the eyes.
- Eye symptoms: Due to cranial nerve involvement, patients may experience:
- Diplopia
- Proptosis (eye bulging)
- Ophthalmoplegia
- Swollen periorbital tissue
- Ptosis (drooping of the upper eyelid)
- Facial pain and numbness: Due to trigeminal nerve involvement.
- Fever and infection signs: Tachycardia, chills, and high fever may be present.
- Altered mental status: Disorientation, lethargy, or coma may occur as intracranial pressure increases and the infection spreads.
Diagnosis
Diagnosing CST can be challenging as its symptoms may mimic other conditions like meningitis or sinusitis. However, in patients with a combination of headache, fever, and ocular or neurological signs—especially with a history of recent sinus or facial infection—a high suspicion for CST should be maintained.
Diagnostic Tools
- Imaging:
- MRI with MR venography is the gold standard for visualizing thrombosis in the cavernous sinus.
- Contrast-enhanced CT scans are also used but are less effective in detecting venous thrombosis.
- Blood cultures: These help identify the causative organism in infections.
- Lumbar puncture: Not typically needed for CST diagnosis, but may be done to rule out concomitant meningitis.
Treatment
Managing CST involves treating both the thrombosis and the underlying infection:
- Antibiotics: Broad-spectrum intravenous antibiotics targeting common pathogens (e.g., Staphylococcus aureus, Streptococcus species) should be started immediately and adjusted based on culture results.
- Anticoagulation: Heparin-based anticoagulation is often used to prevent clot extension and aid in the cavernous sinus’ recanalization, though its use can be controversial.
- Surgery: Drainage may be required if an abscess forms or if there is an uncontrolled source of infection, such as a dental abscess or sinusitis.
- Supportive care: Depending on the severity, treatment for pain, seizures, and intracranial pressure management may be necessary.
Prognosis
If untreated, CST can be fatal. Even with prompt treatment, complications such as:
- Permanent cranial nerve damage
- Brain abscess or stroke
- Sepsis and multiorgan failure
may occur. However, with early diagnosis and aggressive treatment, many patients recover fully or with only minor long-term effects.
Prevention
Preventing CST primarily involves early treatment of infections to prevent their spread. Managing sinusitis, dental problems, and facial infections promptly reduces the risk. In known hypercoagulable conditions, anticoagulation therapy may also help prevent thrombosis.
Conclusion
Cavernous sinus thrombosis is a rare but serious condition that requires immediate recognition and treatment. While advances in diagnosis and therapy have improved outcomes, rapid intervention is essential. Physicians should maintain a high index of suspicion for CST in patients presenting with fever, headache, and ocular symptoms, especially in the context of recent sinus or facial infection.
