Lymphedema (from lymph and edema) is a disorder of the lymphatic system that causes lymph to collect in part of the body. The stagnant lymph, like most stagnant body fluids, is particularly vulnerable to infection. An infection of the lymph is called lymphangitis.
Lymphedema is caused by an interruption in the normal flow of lymph through specialized lymph vessels. These vessels transport the lymph through the body toward the center of the chest. When this normal flow is interrupted, it leads to back up of lymphatic fluid and swelling of the affected area of the body. It is generally painless but can be felt as a heavy or aching sensation. Initially the swelling of lymphedema may be soft enough to leave indentations when pressed firmly with a fingertip for five seconds. Without appropriate intervention however, the swelling becomes firm over time and is no longer reversible. This may lead to difficulty moving the affected part of the body.
Lymph is created when fluid seeps out of small blood vessels (which is a normal process). This fluid is rich in proteins which leak into the space outside the blood vessels along with the fluid. The proteins are too large to leave the space and tend to draw more fluid into the space through osmosis. This protein must be continuously removed. Tiny lymph vessels called lymph capillaries collect this protein and fluid, keeping excess fluid from building up. Lymphatic capillaries start as dead end tubes and which lead from their origins in the periphery of the body into progressively larger lymph channels. The larger lymph vessels are lined with smooth muscle which propels the lymphatic fluid along through peristalsis - sequential contraction of the muscle, similar to the way food is propelled through the esophagus. Lymph is also helped along by the pumping action of muscles and the one way valves throughout the lymph system. Ultimately, the lymphatic fluid reaches one of two large lymph vessels in the upper chest - the thoracic duct on the left and the lymphatic duct on the right. At the end of these vessels, the lymph drains back into the circulating blood stream.
Types of lymphedema
Lymphedema can be divided into primary and secondary types. Primary lymphedema is associated with genetic disorders that create abnormal lymph vessels. It affects about 1:10,000 people and can manifest at birth, at puberty, or after age 35. Secondary lymphedema is due to an acquired condition such as infection, cancer obstructing the lymph vessels, or damage to the lymph vessels caused by surgery or radiation. Treatment for breast cancer can result in lymphedema of the arm on the corresponding side in approximately 20% to 40% of women, depending on the type of treatment they undergo and the location of the tumor. In developed countries, breast cancer therapy is the most common cause of secondary lymphedema. Worldwide the most common cause of secondary lymphedema is filariasis, a parasitic invasion of the lymph vessels and lymph nodes that triggers inflammation. Over time this leads to scarring which obstructs lymph flow and causes elephantiasis.
Lymphedema is not treated with medication. Diuretics, which promote fluid loss from the body, are ineffective for lymphedema. Treatment mainly consists of compression through elastic stockings or sleeves, elevation, manual treatments by specialized physiotherapists, and careful attention to skin care. It is imperative to avoid infections in the affected areas since this can further damage lymph drainage. Areas of lymphedema are particularly vulnerable to infection, because bacteria grow well within the stagnant protein rich fluid.