Giant cell arteritis (GCA)

Vignette says a 55 year old female presented to the neurology clinic with a history of headache in the right temporal region for 7 days; This morning, she experienced sudden episode of blurry vision in her right eye with spontaneous improvement in 15-20 minutes ; She also reports of pain and stiffness in the bilateral shoulders, scalp tenderness while combing hair, jaw claudication with chewing, fatigue, weight loss and mild fever over the past 6 months; Vital signs show blood pressure of 130/80 mm of Hg, pulse rate of 88 bpm, respiratory rate of 18 breaths/min, oxygen saturation of 98% in RA and temperature of 99.9 F; Examination shows tender, thickened right temporal artery with weak pulsation on palpation; Neurological examination is normal; Laboratory studies show ESR of 100 mm/hr, CRP of 75 mg/L; Temporal artery biopsy shows granulomatous inflammation with giant cells and intimal fibrosis; CT angiography shows arterial wall thickening and luminal narrowing of the right carotid artery; Diagnosis?

Diagnosis is Giant cell arteritis (GCA). 

Giant cell arteritis (GCA) is a large vessel vasculitis characterized by the granulomatous inflammation commonly affecting branches of the carotid artery; It is also known as temporal arteritis.

Presents with fever, fatigue, weight loss, unilateral temporal region headache, scalp tenderness, jaw claudication and vision problems; Associated with polymyalgia rheumatica.

The American College of Rheumatology (ACR) criteria for diagnosing temporal arteritis; three of the five criteria must be present to make the diagnosis which includes:-
1. Age greater than or equal to 50 at the onset of symptoms.
2. New onset headache.
3. Temporal artery abnormalities such as tenderness of the superficial artery or decreased pulsation.
4. ESR greater than or equal to 50 mm/hr.
5. Abnormal artery biopsy, including vasculitis (i.e. predominance of mononuclear cell infiltration or granulomatous inflammation, or multinucleated giant cells).

Diagnosis:-
1. CBC shows anemia of chronic disease.
2. Inflammatory markers (i.e. ESR and CRP) are elevated; ESR >100 mm/hr.
3. Creatine kinase is normal.
4. Duplex sonography of the temporal artery shows a "halo sign" (i.e. a circumferential hypoechoic area around the artery).
5. Biopsy shows granulomatous inflammation with giant cells and intimal fibrosis.
6. CTA or MRA shows arterial wall thickening, luminal narrowing and stenosis, contrast enhancement of the vessel wall of the carotid artery.

Management:-
1. Aspirin is given to reduce ischemic complications.
2. Steroids (i.e. IV methylprednisolone is given prior to temporal artery biopsy in order to prevent blindness as giant cell arteritis can lead to irreversible blindness from ophthalmic artery occlusion (AION)); IV methylprednisolone 1g/day is given for 3 days, then switch to oral prednisone 40- 60 mg/day and gradually taper the prednisone.
3. Tocilizumab (monoclonal antibody against IL-6 receptor) is used in patients with relapsing or refractory disease or those needing to reduce corticosteroid use. 
4. Calcium, Vitamin D and Bisphophonates (for osteoporosis prevention).