The Gridlock Between Chronic Cerebral Venous Thrombosis and Dural Arteriovenous Fistulas

Cerebral venous thrombosis (CVT) is a rare condition that occurs when a blood clot forms in the veins that drain blood from the brain. The incidence of CVT is estimated to be 1.3-1.6 cases per 100,000 adults, with a higher prevalence in females than males. Dural arteriovenous fistulas (DAVFs) are abnormal connections between the dural sinuses and the venous system, which can occur as a complication of CVT. The incidence of DAVFs after a diagnosis of CVT is reported to be between 0.9 and 13%. It is believed that a thrombus in the cerebral venous system causes stagnation of blood flow leading to an increase in venous pressure and causing enlargement of pre-existing physiological arteriovenous shunts or neoangiogenesis, resulting in the development of a DAVF. However, it is difficult to establish a causal relationship between CVT and DAVF as most low-grade DAVFs are asymptomatic and lack evidence. High-grade DAVFs are considered to be a more serious form of the condition, as they are associated with a higher risk of intracerebral hemorrhage (ICH) and other neurological complications. In our case series of a total of two cases, all were diagnosed first with CVT, and later in the follow-up imaging, chronic CVT with dural AV fistula was observed. This highlights the importance of long-term follow-up imaging in patients with CVT to detect any potential complications such as DAVF, especially in high-risk patients, and to ensure the prompt treatment to prevent serious complications.