A 65 years old male patient had vision problems following head injury. Examination suggested a cortical type involvement and was confirmed on MRI as right PCA  territory infarct

Fig 1: CT head and MRI T2WI showing chronic right PCA territory infarct

Fig 2: Axial and Coronal CT orbit does not show any definite e/o fracture

The patient was managed on conservative lines.

After  a year he had sudden development of left orbital swelling and proptosis

Fig 3: Axial T2W MRI images showing left proptosis; note the prominent superior ophthalmic veins which prompted for a DSA

Fig 4: DSA showing direct type of RIGHT CCF. Prominent intercavernous venous channels connect to the ipsilateral cavernous sinus to the opposite side from which the LEFT ophthalmic veins fill retrogradely and produce the proptosis. Ipsilateral cavenous sinus also fills but to smaller extent. Also note the reflux into the deep venous system which makes this fistula a dangerous one.

Such findings are not uncommon although most patients will also have clinical manifestations on same side also.

What is rare is the fact that this patient came after a year with proptosis, probably a small aneurysm had developed and ruptured later on.