Cavernous Sinus Thrombosis: Symptoms, Causes, and Treatment

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Cavernous sinus thrombosis


Cavernous sinus thrombosis (CST) is a rare but serious condition where a blood clot forms in the cavernous sinus, a cavity located at the base of the brain behind each eye. This condition typically arises as a complication of infections spreading from nearby structures like the face, sinuses, teeth, or ears.

In this blog we’ll discuss these topics:

What is Cavernous sinus thrombosis?

Cavernous sinus thrombosis (CST) is a rare but serious condition where a blood clot forms in the cavernous sinus, a large vein located at the base of the brain. This sinus is a hollow space bordered by the sphenoid and temporal bones of the skull, through which blood from the brain drains back to the heart. Several important structures, including cranial nerves and the internal carotid artery, pass through or are located near the cavernous sinus.

Symptoms of cavernous sinus thrombosis

Cavernous sinus thrombosis (CST) presents with a range of symptoms due to the critical structures located in and around the cavernous sinus. The symptoms often develop rapidly and can include

Severe Headache

  • Often located behind the eyes or forehead
  • One of the most common early symptoms

Eye-Related Symptoms

  • Swelling and bulging of the eyes (proptosis)
  • Pain or difficulty moving the eyes (ophthalmoplegia)
  • Double vision (diplopia)
  • Loss of vision or partial blindness
  • Redness and swelling of the eyelids

Facial Symptoms

  • Pain or numbness in the face, particularly in the areas served by the trigeminal nerve (such as the forehead, cheek, and jaw)

Systemic Symptoms

  • Fever and chills, indicating infection
  • A general feeling of malaise or discomfort

Neurological Symptoms

  • Altered mental status, including confusion, lethargy, or drowsiness
  • Seizures in severe cases

Other Possible Symptoms

  • Stiff neck, if the infection spreads to the meninges (the protective membranes covering the brain and spinal cord)

Given the severity and rapid progression of CST, anyone experiencing a combination of these symptoms, particularly following an infection in the face, sinuses, or teeth, should seek immediate medical attention. Early diagnosis and treatment are critical to improving outcomes and reducing the risk of complications.

Causes of Cavernous Sinus Thrombosis

Cavernous sinus thrombosis (CST) is a rare but serious condition characterized by the formation of a blood clot within the cavernous sinus, a large vein located at the base of the brain. The causes of CST can be broadly categorized into infectious and non-infectious origins:

Infectious Causes

Bacterial Infections

  • Sinusitis: The most common cause, particularly infections of the sphenoid or ethmoid sinuses.
  • Facial Infections: Infections such as boils or carbuncles, especially around the nose, eyes, and upper lip, can spread to the cavernous sinus.
  • Dental Infections: Severe dental abscesses or other oral infections can lead to CST.
  • Ear Infections: Acute or chronic otitis media can sometimes spread to the cavernous sinus.

Other Infectious Agents

  • Fungal Infections: In immunocompromised individuals, fungi like Aspergillus and Mucor can cause CST.
  • Viral Infections: Rarely, certain viral infections may lead to complications involving the cavernous sinus.

Non-Infectious Causes


  • Head injuries or facial trauma can damage the veins and lead to clot formation.
  • Surgical procedures near the cavernous sinus or in the nasal and sinus regions may inadvertently cause CST.

Systemic Conditions

  • Hypercoagulable States: Conditions that increase the risk of blood clots, such as thrombophilia, pregnancy, oral contraceptive use, and certain cancers.
  • Inflammatory Disorders: Diseases like systemic lupus erythematosus (SLE) or granulomatosis with polyangiitis can predispose individuals to CST.

Medical Interventions

  • Venous Catheters: Placement of central venous catheters in the head and neck region can sometimes lead to thrombosis.
  • Medications: Certain medications that alter blood clotting mechanisms can increase the risk of CST.

Idiopathic Causes

  • In some cases, no clear cause can be identified despite thorough investigation.

Diagnosing Cavernous Sinus Thrombosis

Diagnosing cavernous sinus thrombosis (CST) involves a combination of clinical evaluation, imaging studies, and sometimes laboratory tests. The diagnostic process aims to identify the presence of a thrombosis in the cavernous sinus and determine its underlying cause. Here are the key steps in diagnosing CST

Clinical Evaluation

  1. Medical History and Physical Examination
  • Detailed history of symptoms: Severe headache, fever, facial pain or swelling, vision problems, double vision (diplopia), and neurological deficits.
  • Examination: Look for signs such as eyelid swelling (ptosis), bulging eyes (proptosis), paralysis of eye movements (ophthalmoplegia), and reduced sensation in the face.

Imaging Studies

Magnetic Resonance Imaging (MRI)

  • MRI with Venography (MRV): This is the preferred imaging modality. It provides detailed images of the brain’s blood vessels and can detect blood clots in the cavernous sinus.
  • T1 and T2-weighted MRI: Useful in identifying inflammation, edema, and the extent of thrombosis.

Computed Tomography (CT) Scan

  • CT with Contrast (CTV): Can be used to visualize the veins and identify a clot. It is quicker and more widely available than MRI but provides less detailed images.
  • CT without Contrast: May show indirect signs of CST, such as sinusitis or orbital involvement, but is less sensitive for detecting the thrombosis itself.

Digital Subtraction Angiography (DSA)

  • Considered the gold standard for vascular imaging, though less commonly used due to its invasiveness. It can provide detailed visualization of the cavernous sinus and its venous drainage.

Laboratory Tests

Blood Tests

  • Complete Blood Count (CBC): To check for signs of infection or inflammation.
  • Coagulation Profile: To evaluate for underlying hypercoagulable states (e.g., D-dimer levels).

Lumbar Puncture

  • May be performed to assess cerebrospinal fluid (CSF) for signs of infection or increased intracranial pressure. Elevated CSF pressure and abnormal CSF composition can support the diagnosis, although it is not specific to CST.

Differential Diagnosis

Because the symptoms of CST can overlap with other conditions, it is important to rule out other potential diagnoses such as:

  • Orbital cellulitis
  • Carotid-cavernous fistula
  • Meningitis
  • Brain abscess
  • Stroke

Treatment for cavernous sinus thrombosis

Cavernous sinus thrombosis (CST) treatment typically involves a combination of medical therapy and, in some cases, surgical intervention. Treatment goals are to control the infection, prevent complications, and manage symptoms effectively. Here’s an overview of the treatment approach:

Medical Therapy

1. Antibiotics

  • Broad-spectrum antibiotics are administered intravenously to cover a wide range of potential pathogens, including gram-positive and gram-negative bacteria.
  • Initial therapy is often empirical and may be adjusted based on culture results once available.
  • Duration of antibiotic treatment is typically prolonged, often ranging from 4 to 6 weeks.

2. Anticoagulation

  • Anticoagulant therapy is controversial and not universally recommended. It is considered in cases where there is a high risk of progression or extension of the thrombus.
  • Heparin or low molecular weight heparin (LMWH) may be used cautiously to prevent further clot formation.
  • The decision to use anticoagulation depends on the clinical scenario and should be made in consultation with specialists, considering the risk of bleeding versus the benefits of clot prevention.

3. Symptomatic Management

  • Pain Management: Analgesics are used to manage severe headaches.
  • Fever Control: Antipyretic medications such as acetaminophen are used to control fever.
  • Ocular Symptoms: Lubricating eye drops and ophthalmic consultation may be necessary for managing eye symptoms like proptosis (bulging eyes) and ophthalmoplegia (paralysis of eye movements).

Supportive Care

1. Fluids and Nutrition

  • Adequate hydration and nutrition support are essential, especially in severe cases where there may be systemic symptoms and prolonged hospitalization.

2. Monitoring

  • Close monitoring of vital signs, neurological status, and response to treatment is crucial to detect any complications early.

Surgical Intervention

1. Debridement and Drainage

  • In cases where there is a localized abscess or collection, surgical drainage may be necessary.
  • Surgical intervention aims to reduce mass effect, relieve pressure on surrounding structures, and improve antibiotic penetration into infected areas.

2. Endovascular Therapy

  • In some situations, endovascular techniques such as thrombolysis or mechanical thrombectomy may be considered to directly manage the thrombus.
  • This approach is less commonly used and typically reserved for cases where there is a lack of response to medical therapy or progressive deterioration despite treatment.

Preventing Cavernous sinus thrombosis

Preventing cavernous sinus thrombosis (CST) involves managing and minimizing risk factors that can predispose individuals to this rare but serious condition. While some causes, such as trauma or certain systemic conditions, may be unavoidable, there are measures that can potentially reduce the risk of CST:

General Preventive Measures

Prompt Treatment of Infections

  • Sinusitis: Timely treatment of sinus infections with appropriate antibiotics can prevent the spread of infection to nearby structures, including the cavernous sinus.
  • Dental Infections: Proper dental hygiene and prompt treatment of dental infections can prevent complications that could lead to CST.
  • Ear Infections: Early treatment of otitis media or other ear infections reduces the risk of secondary complications.

Good Hygiene Practices

  • Proper hand hygiene and respiratory etiquette (covering mouth and nose when sneezing or coughing) can help prevent the spread of infectious agents that could lead to sinusitis and subsequent CST.

Management of Systemic Conditions

  • For individuals with conditions that increase the risk of clotting (hypercoagulable states), proper management and monitoring are essential.
  • This may include appropriate anticoagulation therapy under medical supervision, if indicated.

Avoidance of Trauma

  • Taking precautions to prevent head and facial trauma can reduce the risk of injury to the veins around the cavernous sinus.

Specific Preventive Measures in High-Risk Groups

Post-surgical Care

  • Patients undergoing surgeries near the cavernous sinus or in the nasal and sinus regions should receive appropriate post-operative care and monitoring for signs of infection or thrombosis.

Immunocompromised Individuals

  • Those with compromised immune systems (due to conditions like HIV/AIDS, chemotherapy, or immunosuppressive medications) should receive appropriate vaccination and infection prevention measures to reduce the risk of infections that could lead to CST.

Prophylactic Measures in Special Situations

  • In rare cases where there is a known high risk of CST (e.g., certain invasive dental procedures in individuals with pre-existing conditions), prophylactic antibiotics may be considered under the guidance of healthcare providers.

Awareness and Early Recognition

  • Educating healthcare providers about the signs and symptoms of CST can lead to earlier diagnosis and intervention.
  • Awareness among patients about the importance of seeking prompt medical attention for severe headaches, eye symptoms, and neurological deficits can also aid in early detection.


Q1. What is the triad of cavernous sinus thrombosis?

A1. People with cavernous sinus thrombosis often have three main symptoms: fever, headache (50% to 90% of cases), and swelling and pain around the eyes. They may also have vision problems like sensitivity to light, double vision, or loss of vision. These symptoms can appear suddenly or gradually over several days.

Q2. What is the most likely cause of cavernous sinus thrombosis?

A2. Cavernous sinus thrombosis is usually caused by a bacterial infection that spreads from another part of the face or skull. Most cases are due to a staph bacteria infection, which can come from:

  • Sinusitis – an infection of the small cavities behind the cheekbones and forehead.

Q3. What nerve is associated with cavernous sinus thrombosis?

A3. The most common signs of cavernous sinus thrombosis involve the cranial nerves III-VI and include symptoms from impaired blood drainage from the eye and orbit.

Q4. Which teeth can cause cavernous sinus thrombosis?

A4. Cavernous sinus thrombosis can be a late complication of an infection in the central face or paranasal sinuses. It can also result from infections of the ear or upper teeth (maxillary teeth).

Q5. What are the first symptoms of cavernous sinus thrombosis?

A5. Cavernous sinus thrombosis is a rare blood clot that can form after an infection in your face or head. It’s fatal in about 1 in 3 cases. Early symptoms include a severe headache, followed by swelling or bulging in one or both eyes. This condition requires immediate treatment.

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