Spontaneous resolution of direct carotid-cavernous fistulas: case series and literature review

Spontaneous regression of direct carotid-cavernous fistulas (CCFs) is extremely rare. Most of the patients with direct CCFs are usually treated using endovascular techniques. Spontaneous obliteration of the direct fistulas probably results from thrombosis of the venous drainage and/or cavernous sinus. We report spontaneous closure of nine direct CCFs in nine patients. From literature review, we found another 37 patients with 43 fistulas due to spontaneous obliteration of bilateral lesions in six cases. There was no spontaneous closure in large-sized fistula. The factors associated with spontaneous thrombosis of the fistulas may be low-flow and small-sized fistula, hypotension, severe ocular manifestations, dissections or spasm of carotid artery, and increased intracranial pressure. Spontaneous healing of direct traumatic CCFs should be confirmed with cerebral angiography. Conservative treatment of direct CCFs should be carefully restricted in patients with normal vision or minimal visual impairment, and the patients must be monitored closely for any changes in visual function. Prompt endovascular treatment for complete obliteration of the fistula should be performed in patients with rapidly progressive visual loss. Venous thrombosis can still effect vision and rerouting towards cortical veins remains a concern. Because spontaneous resolution cannot be reliably predicted, the fistula then should be treated rather than waiting for spontaneous thrombosis.