A 64 year old lady Kamla complains of severe unilateral headache on the right side and blindness for 2 days. On examination, there is a thick cord like structure on the lateral side of the head. The ESR is 80 mm/hr in the first hour. The most likely diagnosis is:

*Temporal (giant cell) aeritis is an inflammatory disorder involves the extracranial carotid circulation.*Elderly above 50,average age of onset is 70 years,*Women account for 65% of cases.*If untreated temporal aeritis develop blindness due to the involvement of the ophthalmic aery and its branches.*Typical presenting symptoms include headache, polymyalgia rheumatica, jaw claudication, fever, and weight loss.*Scalp tenderness is present, aggravated by brushing the hair, resting on a pillow, worse at night and exposure to cold.*Also reddened, tender nodules or red streaking of the skin overlying the temporal aeries, and tenderness of the temporal or, less commonly, the occipital aeries.*ESR elevated but a normal ESR does not exclude giant cell aeritis.*A temporal aery biopsy followed by immediate treatment with prednisone 80 mg daily for the first 4-6 weeks should be initiated when clinical suspicion is high.Ref - Harrison's internal medicine 20e pg 2583