Signs of Cavernous Sinus Thrombosis
Cavernous sinus thrombosis (CST) presents with multiple characteristic signs beyond the commonly known orbital manifestations, including fever, headache, multiple cranial nerve palsies, and systemic complications that require prompt recognition for early intervention and improved outcomes. 1, 2
Key Clinical Manifestations
Ocular and Periorbital Signs
- Chemosis (conjunctival edema)
- Periorbital edema
- Ptosis (drooping eyelid)
- Ophthalmoplegia (impaired eye movement)
- Proptosis (bulging of the eye)
- Vision changes/disturbances 2
Cranial Nerve Involvement
- Cranial nerve VI (abducens) palsy is most common, resulting in lateral rectus palsy and limited lateral gaze
- Cranial nerves III (oculomotor), IV (trochlear), and V (trigeminal) may also be affected
- Bilateral involvement often occurs within 48 hours of initial unilateral signs 2, 3
Systemic and Neurological Signs
- Fever is present in nearly all cases
- Headache (may be severe)
- Altered mental status
- Seizures
- Signs of increased intracranial pressure
- Papilledema 1, 2
Imaging Findings
- On CT with contrast: "Empty delta" sign (lack of enhancement within the affected venous structure)
- On MRI with contrast: Similar "empty delta" sign within thrombosed sinus or vein
- Increased density and distension of thrombosed sinus on unenhanced CT
- MRI/MRV shows absence of flow in thrombosed dural venous sinus 4, 1
Laboratory Findings
- Elevated inflammatory markers
- Positive blood cultures in up to 70% of cases 2
Complications and Associated Findings
Parenchymal Complications
- Hemorrhagic infarction (occurs in approximately 40% of cases)
- Hydrocephalus (occurs in approximately 10% of cases) 4
Vascular Complications
- Carotid-cavernous fistula may develop as a complication 5
- Extension to other venous sinuses (lateral dural venous sinuses and superior sagittal sinus are commonly affected) 4
Risk Factors and Etiology
- Sinusitis (especially sphenoid and ethmoid) is the most common cause
- Facial infections
- Dental abscesses
- Maxillofacial trauma or surgery
- Otitis media/mastoiditis
- Thrombophilia
- Dehydration
- Oral contraceptive use (especially in females) 1, 2, 6
Diagnostic Approach
MRI with MR venography (MRV) is the preferred imaging modality with highest sensitivity, but CT venography is a reasonable alternative when MRI is contraindicated or unavailable 1.
Early recognition of these signs is critical, as CST carries significant morbidity (with less than half of patients recovering completely) and mortality rates of approximately 30% despite modern treatment 3.
Bilateral eye involvement is particularly characteristic of CST and typically develops within 48 hours of initial unilateral symptoms, representing a key diagnostic clue that should prompt immediate investigation and treatment 3.