Sigmoid sinus thrombophlebitis is inflammation of the sigmoid sinus accompanied by thrombus formation. It is a common otogenic intracranial complication. The infection typically spreads to the sigmoid sinus either directly or indirectly, involving the sinus wall.
Pathology
After infection of the sigmoid sinus, localized inflammation around the sinus can lead to the formation of a perisinus abscess, causing the sinus wall to thicken and become rough. Subsequently, an infected thrombus forms within the sinus cavity. As the thrombus enlarges, it may completely occlude the sinus cavity, forming an occlusive thrombus.
The thrombus in the sigmoid sinus may extend downward to the jugular bulb and internal jugular vein or upward to the superior petrosal sinus, inferior petrosal sinus, sagittal sinus, transverse sinus, or cavernous sinus. If septic emboli detach, they can disseminate through the bloodstream, causing purulent infections in distant organs and septicemia. Local spread of the thrombophlebitis to adjacent tissues may result in complications such as subdural abscess, meningitis, and cerebellar abscess.
Clinical manifestations
Systemic symptoms
Typical cases present with septicemia, characterized by rigors followed by high fever (40 -41°C), severe headache, nausea, and general malaise. Diaphoresis occurs in 2 - 3 hours, and the fever subsides abruptly. These episodes may occur 1 - 2 times daily, resembling malaria.
Some patients may have low-grade fever or no fever, but headache is a common and persistent symptom. If intracranial venous return is obstructed, symptoms of increased intracranial pressure may develop.
Local symptoms and signs
Ear pain on the affected side, along with severe headache, pain in the occipital region, and neck pain are present. If the infection spreads to the mastoid emissary vein, internal jugular vein, or surrounding lymph nodes, mild edema can occur behind the mastoid, and a line may be palpable in the ipsilateral neck with significant tenderness.
Laboratory findings
Marked leukocytosis and an increase in polymorphonuclear leukocytes can be seen. Decreased red blood cell count and hemoglobin levels are present. Blood cultures taken during rigors or high fever may yield the causative pathogen. Cerebrospinal fluid (CSF) analysis is usually normal.
Tobey-Ayer test
Lumbar puncture is performed to measure CSF pressure. If an occlusive thrombus is present in the sigmoid sinus, the Tobey-Ayer test will be positive. Compressing the healthy side's internal jugular vein causes a rapid increase in CSF pressure, which may exceed the original pressure by 1 - 2 times. Compressing the affected side's internal jugular vein results in little to no increase in CSF pressure (only 0.1 - 0.2 kPa). A negative test does not rule out the condition, as venous blood flow may have been rerouted.
Fundoscopic examination
Papilledema and retinal vein dilation may be observed on the affected side. The Growe test can be performed by compressing the internal jugular vein and observing changes in the retinal veins. If no changes occur in the retinal veins during compression, it indicates an occlusive thrombus in the internal jugular vein, confirming a positive Growe test.
Diagnosis
Diagnostic considerations include:
- History of suppurative otitis media or cholesteatoma
- Typical symptoms such as periodic chills, rigors, and high fever
- Imaging studies, including CT, MRI, and angiography (especially digital subtraction angiography), confirming the presence and extent of venous sinus thrombosis
- Differential diagnosis from malaria and typhoid fever
Treatment
Treatment primarily involves surgical intervention, supplemented by adequate antibiotic therapy and supportive care.
Early mastoidectomy should be performed to explore the sigmoid sinus. If a perisinus abscess or necrosis of the sinus wall is identified and no blood return is observed upon puncture, the sinus wall should be incised, the thrombus should be removed, and drainage should be ensured. If there is a simple thrombus without infection, the sinus wall may not need to be incised.
If thorough debridement of the infection fails to alleviate symptoms postoperatively, or if there is persistent anemia, significant tenderness in the affected neck, or metastatic abscess formation, ligation of the affected internal jugular vein should be performed to prevent further dissemination of the infection.
Blood transfusions and other supportive measures should be provided for anemic patients.