Indirect Carotid Cavernous Fistulas Associated with Hypercoagulable State

Hand of a Lab Technician Holding Blood Tube Test. Health Care Researchers Working in Life Science Laboratory. Doctor Holds a Blood Sample Tube in His Hand Testing in the Laboratory
Researchers conducted a study with the largest cohort to date of patients with indirect carotid cavernous fistulas.

The following article is a part of conference coverage from the 2021 meeting of the North American Neuro-Ophthalmology Society, being held virtually from February 20 to 23, 2021. The team at Ophthalmology Advisor will be reporting on the latest news and research conducted by these leading experts in neuro-ophthalmology. Check back for more from the NANOS 2021 Meeting.


Indirect carotid cavernous fistulas (CCF) may be associated with hypercoagulable state (HS), suggesting that patients who receive the diagnosis may need to undergo screening to avoid future thromboembolic events, according to new research on the largest cohort of patients with indirect CCF to date. The study was presented at the North American Neuro-Ophthalmology Society 2021 Annual Meeting.

Indirect CCF, a subgroup of brain dural arteriovenous fistulas (DAVFs), require treatment to avoid complications of orbital venous stasis. Currently, pathogenesis of indirect CCFs is poorly understood, the research explains.

The researchers investigated the presence of HS, which has been associated with future risk of thromboembolic events, among a cohort of patients with indirect CCFs through assessing the medical history and conducting lab testing.

They conducted a descriptive, investigational study based on a retrospective cohort of 22 adult patients with confirmed diagnosis of indirect CCF on neuroimaging and were treated at the same institution between 2003 and 2019.

They screened patients using a clinical questionnaire for hereditary, situational, and acquired risk factors of HS and determined that participants with abnormal lab testing or history of ischemic stroke, atrial fibrillation, cancer, or hereditary disorders associated with hypercoagulability had HS. The patients’ mean age at CCF diagnosis was 59.4 years.

Sixteen patients had HS based on clinical or lab evidence; 5 had a history compatible with HS, 5 had lab evidence of HS, and 6 had evidence based on both. Six patients had abnormal D-dimer while 4 had abnormal homocysteine levels and 4 had abnormal anti-cardiolipin levels. Eleven had abnormal hypercoagulability markers. One patient had been diagnosed with Klippel-Trenaunay syndrome (a hereditary disease that predisposes a patient to HS). No other patients had evidence of hereditary thrombophilia. No patients reported a history of pulmonary embolism (PE) or deep vein thrombosis (DVT).

Of 9 patients on anti-coagulation treatment, 8 had started medication for an indication that had been discovered, on average, 5.5 years after diagnosis of CCF (P =.001). 

“Our results indicate that patients with indirect CCFs have a very high prevalence of HS which contributes to increasing evidence that DAVFs are associated with HS,” the research says. “This study supports the need for patients with newly diagnosed indirect CCFs to undergo a comprehensive hypercoagulability screen in order [to] identify HS early and mitigate the risk of future thrombo-embolic events.”

Limitations of the study included a small sample size, possible selection and survival biases as it was not control-based, and the retrospective nature of the study. Data for HS at the time of initial presentation was limited.

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Jeeva-Patel T, Zaslavsky K, Nicholson P, Margolin E. Hypercoagulability in patients with indirect carotid cavernous fistulas. Presented at: North American Neuro-Ophthalmology Society Annual Meeting; February 20-23, 2021; Poster 7.