Abstract
A 59-year-old man presented with a 2-week history of binocular horizontal diplopia worse when looking to the left. He was diagnosed with a left sixth nerve palsy (6 NP) and had new bilateral findings at a 2-week follow-up with new dilated episcleral blood vessels. Bilateral carotid-cavernous fistulas (CCFs) were suspected and confirmed with CT angiography and catheter angiography. He underwent successful coil and Onyx embolisation of the left cavernous sinus and immediately noticed worsening of the double vision when looking left due to a worse left 6 NP. Three weeks later, he underwent similar treatment of the right CCF and immediately noticed worsening of the double vision when looking to the right and was found to have a worse right 6 NP. His double vision resolved 6 months later. CCFs are rare causes of bilateral 6 NPs and although there is a good prognosis, symptoms may worsen after treatment.