What Are the Symptoms of Cavernous Sinus Thrombosis?

🚨 EMERGENCY ACTION
Cavernous sinus thrombosis is a medical emergency. Do not wait for a routine appointment if you develop a new, severe headache behind the eyes, sudden vision changes, an inability to move your eye, or extreme drowsiness. Call your local emergency services or have someone drive you to the nearest emergency room. Do not drive yourself if your vision or alertness is impaired.

Cavernous sinus thrombosis (CST) is a rare but life-threatening complication that can arise from infections in the face, teeth, or sinuses, including the sphenoid and ethmoid sinuses ^[1][2]. It occurs when a severe infection spreads to the cavernous sinus—a small venous channel at the base of the brain, just behind the eyes, that drains blood from the face and brain and houses important nerves ^[1].

Most people with chronic sphenoid sinusitis never develop CST. However, when a serious infection does reach this area, the resulting inflammation injures the lining of the vein and impairs blood drainage, causing a blood clot (thrombosis) to form ^[1]. This clot blocks blood flow and puts dangerous pressure on nearby cranial nerves ^[1]. Because of the close physical connection between the sphenoid sinus and the cavernous sinus, this condition requires immediate emergency medical attention to prevent permanent vision loss, stroke, or death ^[1][2][3].

Identifying the Red Flag Symptoms

Symptoms of cavernous sinus thrombosis usually develop over a few days as the infection worsens, though they can occasionally happen suddenly. The most common early warning sign is a new, severe, unusual, or rapidly worsening headache or deep pain behind the eyes (retro-orbital pain) ^[4][5]. You should seek urgent medical assessment for this type of pain regardless of whether over-the-counter pain medication temporarily helps.

If you have a sinus infection, seek emergency care immediately if you experience any of the following “red flag” symptoms:

• Eye abnormalities (Ocular manifestations): Because nerves and veins serving the eye run directly through the cavernous sinus, a clot often causes the eye to bulge forward (proptosis or exophthalmos) ^[6]. You may also experience severe eye pain or significant swelling of the eyelids and tissues around the eye ^[7][6].
• Vision and movement problems: You might experience double vision (diplopia) ^[8], blurred vision, or a sudden loss of vision ^[6]. Another major warning sign is an inability to move your eye normally or a noticeably drooping eyelid (ptosis) ^[7][8].
• Signs of severe systemic infection: A high fever, chills, or feeling profoundly unwell can indicate that a local infection has spread ^[7][9]. However, CST can sometimes occur without a high fever; the absence of a fever does not mean your eye or neurological symptoms are safe ^[7].
• Neurological changes: Confusion, extreme sleepiness (lethargy), weakness, or a stiff neck can signal that the infection is affecting the brain or its lining (meningitis) ^[4][10].

It is important to note that these eye symptoms often start in just one eye but can progress rapidly to involve both eyes ^[11][12]. Furthermore, early in the process, your eyes might look perfectly normal ^[5][12]. Never ignore a worsening headache accompanied by neurological changes or signs of a severe infection.

How is it Diagnosed and Treated?

Because cavernous sinus thrombosis and its symptoms can overlap with other conditions like severe sinus infections, meningitis, or migraines, doctors cannot diagnose it at home or through a standard physical exam alone.

If you arrive at the emergency room with these red flags, the medical team will urgently order imaging of your head. This usually involves a contrast-enhanced MRI with MR venography, or a CT scan with CT venography, to look specifically at the blood vessels and evaluate how far the infection has spread ^[13][14][15]. The emergency team will select the best scan based on your condition and equipment availability; do not delay your care trying to request a specific type of scan.

Treatment requires hospitalization and usually involves a multidisciplinary team of specialists, including infectious disease experts, ear, nose, and throat (ENT) surgeons, and neurologists ^[12][7]. Care typically includes:

• Intravenous (IV) antibiotics: High doses of antibiotics are started immediately to fight the underlying infection ^[12].
• Source control surgery: An ENT specialist may recommend urgent endoscopic surgery to drain the infected sphenoid sinus or other infection sources, depending on their assessment of the infection’s location and severity ^[7][16].
• Anticoagulation: Specialists may consider prescribing blood thinners (anticoagulants) alongside antibiotics to stop the clot from growing ^[17][18]. This decision is carefully individualized based on the extent of the thrombosis, any bleeding in the brain, and planned surgeries ^[17]. Never start or stop taking blood thinners on your own.