Pseudogout

Joint swelling and pain are signs and symptoms of pseudogout.

Pseudogout is a type of inflammation of joints (arthritis) that is caused by deposits of crystals, called calcium pyrophosphate, in and around the joints. Pseudogout literally means "false gout." It derives its name from its similarity to gout.

Pseudogout has many similarities to true gout, which also can cause arthritis. However, the crystal that incites the inflammation of gout is monosodium urate. The crystals that cause pseudogout and gout each have distinct appearances when joint fluid containing them is viewed under a microscope. This makes it possible to precisely identify the cause of the joint inflammation when joint fluid is available.

Pseudogout has been reported to occasionally coexist with gout. This means that the two types of crystals can sometimes be found in the same joint fluid. Researchers have also noted that the cartilage of patients who had both forms of crystals in their joint fluid was often visibly calcified, as seen on X-ray images.

Pseudogout is primarily caused by the precipitation of calcium pyrophosphate dihydrate crystals developing within a joint space. Pseudogout has sometimes been referred to as calcium pyrophosphate deposition disease or CPPD.

Pseudogout is clearly related to aging as it is more common in the elderly and is associated with degenerative arthritis. Acute attacks of the arthritis of pseudogout can be caused by dehydration. This is particularly common in hospitalized patients and those recovering from operations, especially when associated with dehydration. Pseudogout can also be caused by the hormonal effects on calcium metabolism from hyperparathyroidism.

Risk factors for pseudogout include:

• Older age
• History of joint trauma (either due to an accident or surgery)

Additional risk factors for pseudogout include:

• Hyperparathyroidism
• Amyloidosis
• Gout
• Degenerative arthritis (osteoarthritis)

Arthritis attacks of pseudogout can be precipitated by dehydration and not infrequently follow surgical procedures in elderly patients.

Pseudogout can result in arthritis in a number of joints. The most common joint affected is the knee, but it can also involve the wrists, shoulders, hips, and/or ankles. Pseudogout usually affects only one or a few joints at a time.

The "attacks" of joint inflammation are characterized by acute joint swelling, warmth, stiffness, and pain. Symptoms may last for days to weeks and can resolve spontaneously. The inflammation leads to loss of range of motion and function of the involved joint.

Pseudogout is treated by general practitioners, family practitioners, internists, rheumatologists, and orthopedists.

Pseudogout is suggested when abnormal calcifications are seen in the cartilage of joints on X-rays. These calcifications are referred to as chondrocalcinosis and are very suggestive of a diagnosis of pseudogout when there is also inflammation of the involved joint.

The diagnosis of pseudogout is ultimately made when fluid from a joint is extracted and examined under a special microscope called a polarizing microscope. With this microscope, the calcium pyrophosphate crystals are clearly identified by their characteristic shape and color (medically term weakly positively birefringent rhomboid crystals).

The arthritis of pseudogout is common in older adults, particularly in the context of dehydration such as occurs with hospitalization or surgery.

The treatment of pseudogout is directed toward stopping the inflammation in the joints:

• Local ice applications and resting can help.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil) and others are often the first drugs of choice.
• Removing fluid containing crystals from the joint can reduce pain and help the inflammation diminish more quickly.
• Cortisone injected into an inflamed joint will also help decrease the inflammation.
• Colchicine (Colcrys) is a medication used to decrease inflammation in patients with gout and may also be helpful in pseudogout.
• Corticosteroids taken as a pill can help if the patient can't tolerate colchicine or NSAIDs.

Long-term prevention of recurrent pseudogout is often best achieved with small daily doses of colchicine and optimal hydration.

Pseudogout can be complicated by difficulty walking and injury to the cartilage and bone of affected joints.

Pseudogout can occur along with aging, be inherited, or be associated with hemophilia, hemochromatosis, ochronosis, amyloidosis, or hormonal disorders (such as hyperparathyroidism and hypothyroidism). These illnesses, as well as others, are considered in the initial evaluation of a patient with pseudogout.

The outlook of pseudogout is generally very good. Aggressive treatment of the inflammation can lead to complete resolution of the inflammation, pain, tenderness, and loss of joint function. While this can last for weeks, the inflammation of resolves within days with proper treatment.

Recurrent attacks of pseudogout and chronic joint inflammation can lead to injury to the affected cartilage and bone.

Patients with known pseudogout should stay well hydrated before and after operations to minimize the risk of attacks of pseudogout. Resting the joints may help during a flare-up.