Spontaneous closure of a cavernous sinus dural arteriovenous fistula with spinal perimedullary drainage (Cognard V) during attempted transvenous embolization

The authors describe a patient with spontaneous closure of a spontaneous cavernous sinus dural arteriovenous fistula (CSDAVF), Cognard type V, during transvenous attempt. A 39-year-old woman experienced mild proptosis, redness of the left eye, and diplopia. Four months later, she developed left retro-orbital pain and left-sided headache. Cerebral angiography revealed the left CSDAVF exclusively draining into the superior petrosal sinus with subsequent drainage into the veins surrounding the medulla oblongata, and finally into the perimedullary spinal veins, classified as Cognard type V. The feeders arise from the dural branches of both the left external and internal carotid arteries. Following 2 h period of attempted transvenous embolization, the fistula disappeared spontaneously. Follow-up angiography obtained 6 months later confirmed complete resolution of the CSDAVF. At 2-year follow-up, the patient has remained clinically asymptomatic. The mechanism of thrombosis in this fistula related to the endovascular procedure. We speculated that putting the wire tip in the draining vein may induce the spontaneous thrombosis in the venous side. In addition, precipitating factors may include small, low-flow fistula, and pre-existing thrombosis.