A rare case of bilateral spontaneous indirect caroticocavernous fistula treated previously as a case of conjunctivitis

Carotid cavernous fistula is an abnormal communication between the carotid arterial system and the cavernous sinus. We present an interesting, rare case of bilateral spontaneous 'Barrow type- C' fistula treated presumptively as conjunctivitis. A 66 year old patient presented in the eye casualty at North Devon District Hospital in January 2016, referred from her General practitioner complaining of bilateral red eyes. She was found to have large, prominently diffused and engorged scleral blood vessels on both sides along with raised intraocular pressures of 26mm of Hg bilaterally. The patient was diagnosed with an indirect carotic cavernous fistulas bilaterally in view of the clinical and radiology findings. Barrow type - C dural fistulas were reported to be seen bilaterally on radiology findings. Patient was referred for interventional treatment to the closest neurosurgical center where she had four failed attempts of coil embolization after which she was referred to a second neurosurgery center at Bristol where she underwent successful coil catheterization as the treatment for her carotid cavernous fistula. Indirect carotid cavernous fistula most commonly occur spontaneously. Bilateral spontaneous indirect carotid cavernous fistula is a very rare diagnosis and and there are very few cases reported in the literature without an underlying etiology or a known cause like Ehlers -Danlos syndrome or diabetes mellitus. Bilateral spontaneous carotid cavernous fistulas are difficult to diagnose due to mild symptoms and no history of trauma. We conclude that carotid cavernous fistulas are a threat to the vision if left untreated due to delayed diagnosis. We recommend considering bilateral carotid cavernous fistula as a differential diagnosis in patients with an ongoing history of red eyes or those unresponsive to conventional topical treatment for conjunctivitis like symptoms.