There is some evidence that a virus may trigger PMR and in the case of GCA the chickenpox virus is found in artery biopsy.
Therefore I started wth a large dose of antiviral 5 x 0.8g/day for 5 days. After 3 days symptoms much better. Three days after stopping symptoms reappeared. Then started 4 x 0.8g/day for 7days and then 2 x 0.8g/day for two months. All symptoms now disappeared.