Pathophysiology of carotid-cavernous fistulas in vascular Ehlers-Danlos syndrome: a retrospective cohort and comprehensive review

Vascular Ehlers-Danlos syndrome (vEDS) is a rare condition characterized by connective tissue fragility. Direct spontaneous carotid-cavernous fistula (sCCF) is reportedly pathognomonic of vEDS. We conducted this study to understand the possible mechanisms of occurrence of sCCF in this subset of patients. We conducted a retrospective analysis of a monocentric vEDS cohort along with a literature review regarding sCCF in this condition. Of 133 patients regularly followed in our centre between 2000 and 2017, 13 (9.8%) had a diagnosis of direct sCCF (92.3% female, median age 33.0 years, interquartile range (IQR) [26.0–39.5]). There were 7 Glycine missense and 6 splice-site variants but no variant leading to haploinsufficiency. The literature search identified 97 vEDS patients with direct sCCF (79.4% female, 7.2% sex not reported, median age 31.0 years, IQR [24.0–39.0]). Increased carotid circumferential wall stress, higher carotid distensibility and lower carotid intima-media thickness could contribute to a higher risk for direct sCCF in vEDS. There is no predictive factor for the occurrence of sCCF apart from female sex in vEDS. In vEDS, anatomical and pathophysiological features of the intra-cavernous internal carotid artery make it prone to shunting in the cavernous sinus, due either to a spontaneous rupture or to a spontaneous dissection with pseudoaneurysm formation. Direct sCCF in seemingly healthy young individuals should be highly suggestive of vEDS and prompt further investigation.