Lymphedema is the swelling of tissues (edema), usually arms or legs, due to obstruction of a lymph channel.
Lymph is clear fluid that seeps out of the blood circulation into the tissues. It returns to the heart through separate channels called lymphatics, carrying waste products and germs. On its way to the heart, it passes through lymph nodes, where infecting germs (including some cancers) are filtered out and attacked by the body's defense mechanisms.
If lymphatic channels are obstructed or inadequate, fluid backs up and causes edema. Tissue fluid can also return to the circulation through tissues, without using the lymphatics, but gravity hinders this flow.
There are two types of lymphedema: primary lymphedema, which occurs when the cause of the lymphedema is congenital (present from birth), and secondary lymphedema, which occurs when the lymphedema is the result of an injury or procedure. There are several types of congenital abnormalities associated with other birth defects of the lymphatics that cause this condition; however, primary lymphedema is rare.
Secondary lymphedema is much more common, and may be caused by many different things. Lymphatics can be damaged or obstructed by many different agents. Repeated bouts of blood poisoning (infection that has escaped local defenses and spread into the circulation) can scar the vessels. Surgery to remove cancerous lymph nodes or radiation therapy can damage them. Lymphedema is often the most serious complication of a mastectomy. Cancer itself, as it invades the lymph system, as well as several other infectious and inflammatory conditions, can result in blockage of lymph flow. The most common worldwide cause of lymphedema is a group of worms known as filaria. Filaria can be found in most of the developing regions of the world. They enter humans through insect bites, mostly mosquitoes, and take up residence in lymphatic channels, irritating them enough to scar them and impair their ability to carry lymph. Long-standing lymphatic filariasis can cause massive swelling of the legs, earning the name elephantiasis.
Because other types of swelling may look similar to lymphedema, precise diagnostic tools must be used. Ultrasound, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans may help with diagnosis. Lymphangiography may be needed to clarify the cause.
Physical activity can pump some of the fluid out of the tissues. Compression stockings are of some value, as are devices that actively squeeze fluid out of tissues. Diuretics may alleviate some of the edema. Because the ability of the skin to defend itself is hampered by the swelling, infections are more common. It is therefore important to care for wounds and to treat infections early.
When caused by infection, lymphedema can be treated by eliminating the underlying infection with antibiotics.
Reconstructing lymphatic channels using microvascular surgery has recently achieved some success.
If congenital, lymphedema is a progressive and lifelong condition. If secondary or caused by an underlying disease or infection, lymphedema can be treated by treating the disease. If secondary lymphedema is not treated promptly, it can lead to a hardening of the tissue in that area, possibly leading to more swelling, and an increased risk of infection.
The physician will diagnosis lymphedema. Nurses and other healthcare team members will help to educate the patient about ways to reduce the swelling and in the use of devises such as compression sleeves. Physical therapists may help patients develop appropriate exercise routines.
When traveling in regions known to have filaria, avoiding insect bites is crucial. Prompt and effective treatment of the infection will prevent the consequences. Treating lymphedema early can help prevent it from becoming more serious. If the patient is known to have had a procedure that places him or her at risk for lymphedema, such as the removal of lymph nodes, prevention of injury to the area, even many years after the surgery, may help to prevent the onset of lymphedema.
See also Antibiotics; Cancer; CT scans; Edema; Magnetic resonance imaging; Mastectomy.
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