Causes of Cavernous Sinus Thrombosis
Causes of cavernous sinus thrombosis are usually rooted in infections that spread from the face, nose, sinuses, or ears into the venous system of the brain. The most common trigger is a bacterial infection, but other risk factors can also contribute. Understanding the causes of CST is key to recognising who may be at risk and how to intervene early.
1. Facial Infections
The majority of cases arise from facial infections, especially in the so-called “danger triangle” — the area stretching from the corners of the mouth to the bridge of the nose. Infections such as furuncles (boils), infected acne, or cellulitis in this region can enter the venous system and travel to the cavernous sinus via valveless veins. These veins allow for direct blood flow to the brain, making this area particularly susceptible.
2. Sinus Infections | Causes of Cavernous Sinus Thrombosis
Acute bacterial sinusitis, particularly in the ethmoid or sphenoid sinuses, is a common cause. If left untreated or inadequately treated, the infection can erode through the sinus wall and reach the cavernous sinus, where it causes inflammation and clot formation.
3. Ear Infections and Dental Abscesses
Though less common, middle ear infections (otitis media), mastoiditis, and severe dental abscesses can also spread to the cavernous sinus. This often occurs through indirect pathways of venous drainage or through contiguous spread in severe cases.
4. Trauma and Surgery
Facial or cranial trauma that damages the veins around the cavernous sinus may lead to clot formation. Additionally, neurosurgical or ENT procedures can, in rare cases, introduce infections or directly injure the sinus, resulting in thrombosis.
5. Blood Clotting Disorders
People with inherited or acquired hypercoagulable states, such as those with antiphospholipid syndrome, factor V Leiden mutation, or certain autoimmune conditions, may be more likely to develop cavernous sinus thrombosis, even in the absence of infection.
6. Intravenous Drug Use
Although rare, intravenous drug use may increase the risk of bloodstream infections that could spread to the brain’s venous system, particularly if unclean needles are used.
Recognising the causes of cavernous sinus thrombosis is critical in both prevention and early diagnosis. Prompt treatment of facial infections, sinusitis, and ear infections, particularly in vulnerable individuals, can significantly reduce the risk of this dangerous complication.
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