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Introduction: PMR and GCA are related
conditions affecting adults over the age of 50. Both are
inflammatory diseases, with PMR involving the large joints of
the hips and/or shoulders and GCA involving large and medium
sized blood vessels.
PMR occurs in about 30 individuals over the age
of 50 per 100,000 population per year, while GCA is roughly
half as common. Both conditions are about twice as common in
women as in men and are seen most commonly in those of
Northern European descent. The average age of onset is about
70 for both conditions, and with the aging population the
prevalence of these disorders is expected to increase in the
next few decades.
While the cause of these conditions is unknown, the
fact that they tend to occur in cooler climates and in
clusters of cases every several years suggests that infections
may trigger PMR and GCA. Having certain genes also seems to
increase the risk of developing either of these disorders.
Features of PMR: Patients
with PMR tend to experience widespread pain in the regions of
the shoulders, upper arms, neck, hips, buttock, and thighs.
These symptoms may be sudden in onset and are accompanied by
up to several hours of morning stiffness. While swelling of
knees, elbows, or wrists may occur, there is most often no
visible joint swelling but only difficulty with movement of
the larger joints. A small percentage of patients may
experience swelling of the entire hand and foot with edema,
or excess fluid accumulation. These individuals are difficult
to distinguish from rheumatoid arthritis (RA).
Fever, fatigue, weight loss, and anemia are often
encountered in PMR and seem to be the result of the
inflammation present in the large joints. Patients typically
find these symptoms quite debilitating and seek a physician�s
care within a few months of their onset. The good news is that
PMR is not only highly treatable, but most cases last no
longer than 2 years before resolving, and PMR leaves behind no
noticeable joint damage.
About 15-30% of patients with PMR develop GCA, which
can occur any time during the course of the illness. GCA can
either occur before, after, or at the same time as PMR in a
given individual.
Features of GCA: The most
common symptom of GCA (also known as temporal arteritis)
is headache, typically located around the temple, but any
new headache in someone over the age of 50 could potentially
be a sign of GCA. This symptom is the result of inflamed blood
vessels in the scalp. These blood vessels may become swollen,
tender, and blocked as the disease progresses. Involvement of
other nearby blood vessels can cause pain in the jaw with
chewing or pain in the tongue with talking.
The most feared complication of GCA is loss of vision,
which can occur suddenly and without warning. More frequently,
patients will experience warning signs of temporary visual
blackouts or double vision. Overall, up to 20 or 25% of those
with GCA experience some form of vision loss, resulting from
blood vessel inflammation leading to occlusion. Much less
commonly, strokes can also occur.
Fever, fatigue, weight loss, and many similar symptoms
that can occur in PMR also may be seen in patients with GCA.
Moreover, about 40-50% of GCA patients have PMR.
While the inflammation more commonly occurs in blood
vessels located above the neck, 10-15% of patients can
experience narrowing of blood vessels leading to the arms or
dilation of the aorta, the large vessel leading out of the
heart, as a result of GCA. In such patients, reduction of
blood pressure in one arm or complete loss of pulse may occur.
Other less common symptoms include sore throat, dry cough, and
toothache, all of which pose a challenge to physicians
attempting to diagnose this condition.
Diagnosis: When evaluating someone who
may have PMR or GCA, reviewing a history of the illness is the
best place to begin. Anyone over the age of 50 who experiences
new onset symptoms similar to those described above warrants
further investigation.
Laboratory tests can provide some valuable clues to the
diagnosis of both PMR and GCA. Markers of inflammation such as
the sedimentation rate and C-reactive protein
are usually elevated, often dramatically. Any other
inflammatory or infectious disease, however, can also cause
elevations of these markers. Moreover, normal or only mildly
elevated values on these tests are seen in about 15-20% of
those with both PMR and GCA. For this reason, these tests are
most meaningful when coupled with the patient�s symptoms.
Anemia and elevations of liver enzymes are less commonly
observed findings. Antibodies seen in RA or systemic lupus
erythematosus (SLE) are typically absent in PMR and GCA.
The importance of making an accurate diagnosis is
greater for GCA than for PMR. Missing the diagnosis can result
in serious complications, while incorrectly making the
diagnosis can needlessly expose a patient to the side effects
of therapy. For this reason, a more accurate method of either
excluding or confirming GCA is essential. For most patients,
this involves obtaining a temporal artery biopsy.
The temporal artery is located just in front of
the ear and leads to the scalp. It can be easily sampled under
local anesthesia with minimal complications, and no impairment
in circulation occurs once it is removed. When inflammatory
cells are seen within the blood vessel wall, the diagnosis of
GCA is secure. Overall, about 85% of patients with GCA have
such findings when their temporal arteries are examined under
the micro-scope. How to treat those remaining 15% with
negative biopsies that have otherwise classic features of GCA
is controversial, but these individuals seem to have fewer
complications and could be treated less aggressively.
Those with GCA demonstrating inflammation in
larger blood vessels may be best diagnosed by certain x-ray
studies. An arteriogram, where dye is injected into
blood vessels to detect abnormalities compatible with GCA is
an appropriate study to pursue when there is any reason to
suspect disease involving the vessels leading to the arms.
Such patients have fewer positive temporal artery biopsies.
Magnetic resonance imaging (MRI) studies or ultrasound are
other options for imaging the vessels that do not involve
needle sticks or dye, but the detail in blood vessel walls may
not be as precise. Some recent studies have suggested that
ultrasound of the temporal artery may one day be an
alternative to biopsy, but this procedure still needs to be
refined.
Therapy for PMR:
In many ways, the therapy for PMR is also part of the
diagnosis. Corticosteroids at relatively low doses
(10-20 mg/day of prednisone, for example) typically produce
such a dramatic reduction in pain and stiffness within one
week (or even within a day or two) that a prompt response
helps to confirm the diagnosis of PMR. If such a response is
seen in a patient with suspected PMR, the dose of steroids can
be slowly reduced and eventually discontinued without a return
of symptoms. In the majority of individuals, 1-2 years of
therapy is necessary to adequately suppress disease activity.
In a minority, higher doses of corticosteroids
may be required, reductions in the dose may result in a return
of symptoms, or a longer duration of therapy may be required.
In such patients, methotrexate (MTX) has been
shown in a recent study to allow steroids to be decreased
successfully. Some of these individuals with features of PMR
that are resistant to therapy must be observed carefully for
the development of GCA or progression to RA.
Corticosteroids may cause weight gain,
elevation of blood sugars, cataracts, weakening of the bones,
and increased susceptibility to infection. While steroid side
effects are of concern when therapy is given for more than 6
months, the fact that low doses are sufficient to treat PMR
minimizes these complications.
Therapy for GCA:
As with PMR, the treatment of choice for GCA is
corticosteroids, but at a much higher dose. Prednisone at a
dose of 40-60 mg/day is the recommended initial dose to
suppress inflammation and prevent complications (vision loss,
for example). This therapy can be started in a patient in whom
GCA is strongly suspected before the temporal artery biopsy
without affecting the results. Also as with PMR, the dose is
gradually reduced over about 2 years, adjusting based on the
presence of GCA symptoms, and eventually discontinued.
Unfortunately, the dose of steroids required to
treat GCA frequently results in side effects in this age group
that is typically being treated. Bone density measurement,
calcium and vitamin D supplements, and additional therapies if
needed can help prevent osteoporosis (see related section) and
are recommended in steroid-treated patients. Other side
effects listed above, however (see Therapy for PMR
section), are more difficult to prevent.
To help reduce corticosteroid doses, other
therapies have been sought. There have been conflicting
reports about the effectiveness of MTX in treating GCA.
Azathioprine (Imuran), another drug that suppresses the
immune system, has been shown to be helpful as a
�steroid-sparing� drug. Newer medications know as TNF
antagonists (namely, infliximab and etanercept)
have been attempted in small studies and may be helpful but
are expensive and must be given either intravenously or by
weekly injection.
Strangely enough, the most promising �new�
therapy for GCA may be aspirin! A recent study
suggested that patients taking aspirin along with
corticosteroids experience fewer complications, such as vision
loss, as compared with those only on corticosteroids. Further
research is needed, but it is reasonable at present to
recommend low dose daily aspirin for treatment of GCA due to
the low expense and relatively low rate of side effects of
this therapy.
All in all, PMR and GCA are treatable illnesses
with a good long-term outlook as long as the diagnosis is made
and adequate therapy is initiated promptly. |
