<prompt> What is not a feature of carotico-cavernous fistula?Pulsatile exophthalmosGenerally post traumaticDilated superior ophthalmic veinCan lead to spontaneous intra orbital hemorrhage  <response>: Ans DCaraticocavernous fistula is mostly secondary to penetrating trauma associated with fractures of the facial bone and this leads to pulsatile exophthalmos which coincides with pulse. On imaging the shunting of blood from artery to vein is so fast that only the superior ophthalmic vein which is carrying extra blood volume is identified. The actual fistula can be demonstrated on digital subtraction angiography 