Case Presentation: A 54-year-old male was referred to our hospital with a headache and left ophthalmalgia since a few weeks. The patient had a 6-month-old history of odontalgia and gingivalgia, but lived an otherwise healthy lifestyle. Physical examination revealed left conjunctival hyperemia, periorbital swelling, and vertical diplopia. In addition, contrast-enhanced head computed tomography (CT) and magnetic resonance imaging (MRI) revealed dilatation and poor contrast enhancement lesions in the left superior ophthalmic vein, swollen cavernous part of the internal carotid artery, and left periorbital inflammation. Although we initiated symptomatic therapy and heparinization for thrombosis, manifestations of sepsis, such as high fever, chillness, and impaired consciousness appeared with worsening of MRI results. Thus, the patient was diagnosed with infectious cavernous sinus thrombosis (CST), which we treated using broad-spectrum antibiotics. Although the detection of thrombosis usually indicates the presence of other diseases, such as coagulation disorder, collagen diseases, or malignancy, we deemed these to be unlikely in the present case because laboratory examinations and imaging revealed no such abnormalities. In the quest of identifying the potential cause of infection, the blood, urine, and spinal fluid cultures tested negative and no sinusitis was observed. However, the oral cavity was contaminated, and periodontitis was observed on the left side of the oral cavity. Accordingly, we conducted teeth extractions, periodontal abscess drainage, and oral care. Eventually, the periodontal abscess drainage culture tested negative, which could be attributed to the administration of antibiotics before drainage cultures were performed. Both anticoagulation therapy and antibiotics reduced fever and dissolved impaired consciousness besides improving ophthalmalgia and periorbital swelling. After confirming a reduction in thrombus in the left superior ophthalmic vein, the patient was discharged, and anticoagulation therapy was continued on an outpatient basis.

Discussion: CST is a rare, life-threatening intracranial complication of rhinosinusitis, facial skin infection, or dental infection. In adults, while the mortality rate of CST is nearly 30%, its associated morbidity can result in stroke, ophthalmoplegia, and blindness. The most common causative microorganism of CST is Staphylococcus aureus. The characteristic symptoms and signs of CST include fever, ptosis, proptosis, chemosis, cranial nerve palsy, headache, periorbital swelling, and papilloedema. Most of these symptoms were observed in the current case. Contrast-enhanced CT and MRI are the most sensitive imaging modalities in diagnosing CST. For a definitive diagnosis of CST, clinicians should obtain bacterial cultures from all possible sources. For the treatment of CST, appropriate antibiotics and early drainage of the primary infectious sites are indispensable. Although anticoagulation therapy is often prescribed to patients with CST, the evidence of its efficacy is lacking.

Conclusions: Although CST is a sporadic disease, its mortality rate remains high. Both scarcity and anatomical complexity render the diagnosis of CST challenging. Despite CST diagnosis, the detection and identification of causal pathogens are sometimes challenging. Hence, a prompt diagnosis and an antibiotics-based therapy are warranted to reduce the morbidity and mortality rate of CST.