Post-Traumatic Carotid-Cavernous Fistula on Magnetic Resonance Imaging (MRI): a Case Report and Review of Imaging

Carotid-cavernous fistula (CCF) is an abnormal vascular connection between the carotid arteries or their branches and the cavernous sinus. It can be direct or indirect depending on the site of the fistula. It is a rare abnormality. CCF results in shunting of blood from the artery to the venous system leading to retrograde flow in the draining veins and possible brain ischaemia. Imaging is fundamental in the diagnosis and evaluation of complications. We report a rare case of CCF on MRI with review of imaging. An 18-year-old male presented with a week history of painful swollen left eye following road traffic accident. There was associated watery discharge, proptosis and poor vision. There was also history of headache which was generalized. On examination, the vital signs were normal. There was proptosis, peri-orbital oedema, redness and reduce vision in the left eye. A bruit was felt in the left eye. The right eye examination was unremarkable. The multisequence MRI of the orbit and brain show proptosis of the left eye with thickened extra-ocular muscle and orbital oedema. The superior orbital vein was grossly dilated and shows early contrast filling after intravenous gadolinium administration. In addition, there was cerebrospinal fluid collection (CSF hygroma) in the left retro-orbital region. The right orbit was normal. No intracranial aneurysm or haemorrhage was demonstrated. A diagnosis of left carotid-cavernous fistula was made.