I was diganosed w/promient cisterna magna. mri said it was a normal variant. i've had a lot of headaches&now my eyes are swelling 2gther. what is th?

Some dogs have fleas: Some dogs have ticks. Some dogs have fleas AND ticks. The message is that there is no reason to think that there is any connection between your mega cisterna magna and your present problem. I would be very surprised if they were at all related. By "eyes swelling together" I assume you mean exophthalmos, not papilledema. Hustle off to the doctor pronto and get checked out.