Hi @jennywren, GCA can cause stroke or blindness if untreated and a higher dosage of prednisone than that for PMR is needed to manage it.
I had PMR untreated a year, then symptoms of GCA including some visual disturbance. Strange symptoms came and went. GCA was confirmed by a temporal artery biopsy and I was put on 40 mg of prednisone, tapering down by 5 mg every two weeks. I also had monthly CRP tests to monitor inflammation. As the dosage of prednisone reduced, I tapered down a couple of mg every two weeks. This went on for about 18 months. I've been off prednisone for nearly a year.
I was prescribed a low dose aspirin every day as GCA can cause aortic complications even for those in remission. I was also told that if my visual symptoms returned to immediately go to the ER for treatment or I could go blind.
The thing is, if not treated properly, the immune system will continue to attack different arteries etc. in the head. I don't think there's any such thing as mild GCA. A physician friend told me it's the closest thing to an emergency in rheumatology.