Jama 2005;295:2525; Nejm 2003;349:160; 2002;347:261; Ann IM 2003;139:505
Cause:Autoimmune
Pathophys:TA is a large vessel vasculitis (r/o Takayasu’s arteritis—Ann IM 1985;103:121); a spectrum from a little patchy involvement of medium vessels with arteritis in PMR to much more w TA. Muscle pain in TA is probably claudication whereas in PMR is due to periarticulitis or bursitis. Blindness in TA from acute anterior ischemic optic neuropathy from ciliary artery occlusion
TA 15-25/100000; female/male 17:1; always in patients over age 50 yr, peaks in 70s. Cyclic incidence w 10-yr peaks (Ann IM 1995;123:192). Occasionally associated w HLA DR4 (J Rheum 1983;10:659). Incidence over age 50 yr of PMR = 1/133
Sx:Fever; polymyalgia syndrome w muscle aches and weakness esp in quads (33%) (Ann IM 1995;123:192) and upper arms (“can’t use my arms over my head”) from pain not myopathy; headache (77%) and scalp pain; sore throat and cough (Ann IM 1984;101:594); leg, tongue, and jaw claudication; weakness, malaise, and weight loss; synovitis, shoulder and hip pain
Si:Fever (27%) up to 103°F; mild muscle tenderness, asx knee effusions (8/18), tender indurated temporal arteries (67% sens, 99% specif in TA—Ann IM 2002;137:232), cherry red macular spot of retinal artery occlusion
American College of Rheumatology criteria (Arth Rheum 1990;33:1122) 3/5 of following findings:
- Age >50 yr
- New localized headache
- Temporal artery tender or diminished pulse
- ESR >50 mm/h
- Biopsy pathology positive
PMR and TA resolve in ±2 yr; 30-50% recurrence. No increased mortality with PMR (Ann IM 1978;88:162)
Sudden cranial nerve defects (17%), esp blindness, preventable with steroids and occurs in 1st 12 weeks if going to; psychosis; MI and CVA are the most common causes of death; aortic dissections and thoracic aneurysms (Ann IM 1995;122:502); hypothyroidism (5%) (Brit J Rheum 1991;30:349)
~50% of pts w TA may get PMR, ~5-15% of those w PMR will get TA
Lab:
Chem:Normal muscle enzymes, negative rheumatoid titer; Alk phos often slightly elevated
Hem:ESR elevated (increased 
2-globulin >40 mg % [97%]), usually >100, often only abnormal test; elevated CRP; crit = 30-40% in 14/18, Hgb <11 gm % (23%)
Path:Muscle bx normal; temporal artery bx (take 3-4 cm) shows patchy (easily missed) giant cell arteritis, which remains positive even after 14 d of prednisone rx (Ann IM 1994;120:987); do it if palpably abnormal arteries or claudication sx in their distribution
Urine:UA usually normal
Xray:
Color duplex US of temporal arteries shows hypoechogenic edema around arteries, “halo sign” (73% sens, 100% specif?) (Nejm 1997;337:1336, 1385) vs much worse (meta-analysis—Ann IM 2005;142:359)
Annual chest xray to watch for thoracic aneurysm
MRI of joints shows synovitis
Rx: of TA: Prednisone 40-60 mg (10-15 mg for PMR) po qd × 4-12 wk, then decrease to control sx’s; keep up at least for 2 yr (Ann IM 1972;77:845); qod doesn’t work (Ann IM 1975;82:613); use calcium and vitamin D to prevent osteoporosis bisphosphonates if bone densities diminished
Methotrexate 10 mg po q 1 wk allows lower steroid doses (Ann IM 2001;134:106; Arth Rheum 1991;345:A43) in TA; not clearly helpful in PMR (Ann IM 2004;141:493, 568)
of PMR: Prednisone 10-15 mg, often split bid, and response w/i 1-2 wk confirms dx; after 1 mo, taper to minimal dose; usually need for 
3 yr