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 circulationElderly above 50, the average age of onset is 70 yearsWomen account for 65% of casesIf untreated temporal aeritis develop blindness due to the involvement of the ophthalmic aery and its branchesTypical presenting symptoms include a headache, polymyalgia rheumatica, jaw claudication, fever, and weight lossScalp tenderness is present, aggravated by brushing the hair, resting on a pillow, worse at night and exposure to coldAlso reddened, tender nodules or red streaking of the skin overlying the temporal aeries, and tenderness of the temporal or, less commonly, the occipital aeriesESR elevated but a normal ESR does not exclude giant cell aeritisA 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 18/e p114)