By: Sara M. Aksoy
One of the lesser known forms of arthritis,
psoriatic arthritis is a disease linked to the skin condition,
psoriasis. Affecting up to three percent of the population,
psoriasis is generally characterized by an itchy, flaky skin rash
often found on the elbows, knees, and scalp. Psoriatic arthritis
affects between five and eight percent of individuals with
psoriasis.
While the causes of psoriasis and psoriatic
arthritis are not yet known, they are suspected to stem from
several factors. These include genetics, environment, and
changes in the body’s immune system.
Studies with twins, families, and entire
populations have all suggested that there is a genetic influence
in the development of psoriasis. This genetic link is not direct
and it is believed that a number of genes play a role in the
disease.
Environmental factors influencing the
development of the disease include both infectious agents and
physical trauma. A history of specific infections has been linked
to psoriasis, suggesting that they or the immunologic response
that they trigger may play a role in the pathogenesis of the
disease. Trauma has also been named as a potential factor in
psoriasis, and this may be due to the body’s chemical
response to the trauma.
The immunologic theory is related to
abnormal immune responses. When this malfunctioning immune system
is exposed to a bacteria or fungal agent that results in immune
stimulation for a prolonged amount of time, psoriatic arthritis
may develop.
Psoriatic arthritis can affect a number of
joints including the spine, wrists, knees, ankles, and those of
the fingers and toes. Approximately one-third of those affected
with the arthritis have spine involvement. While in some the
arthritis is confined to the spine, in about ninety-five percent
of people other joints are affected as well. In fact, in most of
those with multiple-joint involvement, more than five joints are
arthritic.
The presentation of psoriatic arthritis in the joints is varied.
In most forms of arthritis joint involvement can be defined as
symmetrical, where the same joint is affected on both sides of
the body, and asymmetrical, where it is not. However, psoriatic
arthritis appears differently in different patients, and can be
either symmetrical or asymmetrical.
Symptoms of psoriatic arthritis include pain and stiffness in the
affected joint. When the inflammation is present in the fingers
and toes, it may give the digit a sausage-like appearance.
Diagnosis of psoriatic arthritis begins with
a physical examination to check for signs of psoriasis. Some
symptoms of psoriasis, such as pitting of the nails, occur more
commonly in patients with the arthritic form of the disease, and
can be good indicators for considering the disease’s
presence. X-rays may also be taken to look for degenerative
changes in the joint that could indicate the presence and extent
of the disease.
Because psoriatic arthritis bears similarities to several other
forms of arthritis, tests may be taken to eliminate other
possibilities. For instance, psoriatic arthritis resembles
forms of inflammatory arthritis such as rheumatoid arthritis, and
blood tests may be taken to rule these out. A joint fluid sample
may be taken as well to eliminate the possibility of gout.
There is no cure for psoriatic arthritis, so
treat-ment options are aimed at relieving the symptoms. While in
most cases this treatment is limited to reducing joint
inflammation and pain, in about twenty percent of people the
arthritis becomes more destructive, causing damage to the joint.
This damage results from chronic inflammation of the synovial
membrane that lines the joint, and requires additional medication
to slow the progression of joint degradation.
Non-Steroidal Anti-Inflammatory Drugs
(NSAIDs) relieve the inflammation associated with the arthritis,
and therefore relieve pain. NSAIDs can be found in both
prescription and over-the-counter forms and include drugs such as
Motrin, Aleve, and Relafen. One drawback to NSAIDs is their
effects on the gastrointestinal tract. In their actions blocking
inflammation, these medications also interfere with the
stomach’s normal defense system and may result in
gastrointestinal bleeding or ulceration.
COX-2s, a new class of NSAIDs, provides the
anti-inflammatory benefits without the side effects of
traditional NSAIDs. This group includes Celebrex, Vioxx.
Glucocorticoids are another form of anti-inflammatory drug, however, they tend to be used in only severe cases of inflammation. They are a synthetic form of a natural anti-inflammatory hormone that the body makes and may be administered by pill, injection into the joint, or in the form of a cream.
A group of medications used for treatment of
rheumatoid arthritis, Biologic Response Modifiers appear to play
a role in treating psoriatic arthritis as well. These drugs
reduce inflammation in the inflammatory forms of arthritis.
Etretinate is an anti-psoriatic drug used to
treat psoriatic arthritis. However, its action interferes with
bone growth and it should therefore not be used in children.
Disease-Modifying Anti-Rheumatic Drugs
(DMARDs) are used to slow the progression of inflammatory forms
of arthritis such as psoriatic arthritis. While these are fairly
slow acting, they are intensely powerful drugs. As DMARDs slow
the progression of psoriatic arthritis, they are most effective
when taken during the early stages of the disease. A wide range
of DMARDs exists, each with its own set of benefits and
drawbacks. It is therefore important to understand the different
forms and talk to your health care provider about which type is
best for you.
Effective treatment for psoriatic arthritis
will include medication, exercise, good diet, and low stress,
among other things. For more information about psoriatic
arthritis, please contact the Arthritis Foundation at
www.arthritis.org.