Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA)
frequently affect the same types of people. The diseases may occur independently
or in the same patient, either together or at different times.
Who is affected by PMR and GCA?
People over 50 years old are typically affected with PMR and GCA. The
average age of patients is 74. One-third of patients with GCA also have PMR.
Both diseases are two to three times more common in women than
men, and there is a higher incidence among Caucasians than any other ethnic group.
What causes PMR and GCA?
The exact cause of these illnesses is unknown.
What is giant cell arteritis (GCA)?
Giant cell arteritis causes inflammation that damages the arteries (blood
vessels that carry blood and nutrients from the heart to tissues in the body).
The large- and medium-sized arteries are affected.
Because some of the affected arteries provide blood to the head
(cranium), including the temples, the condition may also be called cranial or
temporal arteritis.
What are the symptoms of GCA? How often do they occur?
- Atypical severe headaches are the most common symptom and occur in over
80% of patients.
- Scalp tenderness, fatigue, fevers and a general sense of illness occurs
in about 50% of patients.
- Jaw or facial soreness, especially with chewing, also occurs in about 50% of patients.
- Vision changes or distorted vision caused by decreased blood flow occur
in 15 to 50% of patients; blindness occurs in 5 to 15%.
- Stroke may occur in less than 5% of patients and is caused by
decreased blood flow to the brain.
- The large blood vessels may become narrowed or enlarged (aneurysm); see
figure. If narrowing occurs in the blood vessels leading to the arms or
legs, patients may notice fatigue or aching in the limbs because of a
reduced blood supply. Weak or absent pulses may be noticed by the doctor.
These symptoms occur in 15 to 20% of patients.
A blood vessel can become inflamed and narrowed, or segments of a blood vessel can weaken and stretch (aneurysm). When aneurysms occur, they are usually present in the aorta, the body’s largest vessel that carries blood from the heart. When blood vessels become narrowed, there is restricted blood flow. If the blood vessel is completely blocked (occluded), there is no blood flow through that segment.
How is GCA diagnosed?
The diagnosis of GCA is based on the presence of previously noted symptoms
and/or the finding of abnormal blood flow in the arms, legs, or aorta;
tenderness of the scalp or temples; visual abnormalities; and a high ESR. The
ESR (erythrocyte sedimentation rate) is a blood test that simply measures the
rate at which red blood and other cells settle towards the bottom of a tube. A
rapid or high rate usually correlates with ongoing inflammation. While the test
is good, it is not perfect, and the diagnosis of GCA may sometimes be made even
when this test is normal.