Spontaneous carotid-cavernous fistula: challenges in clinical and radiologic diagnosis

We present a 47-year-old female patient with spontaneous carotid-cavernous fistula without comorbidities. The symptoms of a carotid-cavernous fistula may be confused with other pathology in the region of the orbit and cavernous sinus such as cavernous sinus thrombosis. Carotid-cavernous fistulas most commonly result from direct injury to the internal carotid artery, as with skull base or surgical trauma, but it can also result from weakness in the arterial wall, as with an aneurysm. Because of the high flow of the internal carotid artery, carotid-cavernous fistulas typically present with rapidly progressive symptoms. The case study presented demonstrates the usefulness of radiologic studies in distinguishing between these similarly presenting disease processes. Clinically, cavernous sinus thrombosis generally presents bilaterally and carotid-cavernous fistula presents unilaterally; however, there are a number of exceptions in the literature. The use of a variety of radiologic and angiographic studies will help differentiate between these pathologies. On magnetic resonance imaging, both pathologies can appear as an enlargement of cavernous sinus. Magnetic resonance angiography sequence can reveal aneurysms communicating with the cavernous sinus, and magnetic resonance venography will define thrombosis within the cavernous sinus. Differentiating between cavernous sinus thrombosis and carotid-cavernous fistula can be clinically difficult, and a team approach including emergency physicians, neurosurgeons, ophthalmologists, and otolaryngologists will be called upon to assist in diagnosis. Prompt diagnosis and management can allow for potentially vision and lifesaving interventions.