A 75 year old lady wakes up with sudden painless loss of vision. She gives history of scalp tenderness and cramp like pain on eating. O/E there is a pale disc edema, has an inferior altitudinal field defect. What is the likely cause?

Symptoms of GCA -such as Headache and tenderness of the temporal aeries and scalp. Jaw claudication, characterized by pain on speaking or chewing, is pathognomonic of GCA,caused by ischaemia of masseter muscle Other symptoms include fever, malaise, anorexia, weight loss, night sweats and joint and muscle pain. GCA is extremely unlikely under 55-60 years. It constitutes an ophthalmic emergency.