What is lymphedema?
Lymphedema is the swelling, usually of an extremity, resulting from poor or abnormal drainage of fluid through the lymphatic system. Lymphedema is classified into two types: primary or secondary. Primary lymphedema is thought to result from an inherited abnormality of the lymphatic system such as hypoplasia (decreased number or size of lymphatic vessels) or hyperplasia (too many lymphatic vessels which do not function properly). Primary lymphedema can be further classified by its mode of inheritance and its age of onset as described here. Secondary lymphedema is the result of damaged or blocked lymphatic vessels caused by surgery, radiation therapy, injury, limb paralysis, infection, or an inflammatory condition. Surgery combined with radiation therapy for breast cancer is a common cause of upper arm secondary lymphedema for women in the United States. Parasitic infections (filariasis) account for many cases of secondary lymphedema in tropical regions.
What is the function of the lymphatic system?
The circulatory (blood) system is comprised of two separate components: the venous system which returns blood to the heart, so that it can pass through the lungs to get oxygen, and the arterial system which delivers this oxygenated blood to the tissues. The lymphatic system, however, works on a one-way principle, the purpose of which is to drain lymphatic fluids from the tissues, where it collects. Lymphatic fluid, also called "lymph," consists of four components: protein, water, dead cells and toxins, and some fats. Approximately half of the total protein found in the blood and 1-2 liters of water escape from the bloodstream into the tissues each day and are returned to the bloodstream through the lymph. If the lymphatic system did not return this fluid to the bloodstream, it would collect in the tissues (such as the feet or legs) resulting in swelling. In addition, the lymphatic vessels of the intestines are the only location capable of absorption of certain fatty acids. Finally, the lymph nodes filter this lymphatic fluid to remove cell debris, cancer cells, bacteria, and toxins from the tissues, before the remaining fluid is deposited into the major vessels of the venous system.
How does lymphedema occur in the body?
If the lymphatic system is damaged, blocked, or abnormally developed, protein-rich fluid accumulates in the tissues, resulting in chronic swelling. This in turn leads to increased blood flow through an increase in the size and number of blood vessels. The resulting rise in temperature of the area, in combination with the protein-rich fluid, provides a medium for bacteria, making recurrent infection a significant problem. These infections place an increased load on the lymphatic system, which can then worsen the condition.
What are the symptoms of lymphedema?
Symptoms of lymphedema include tightness and swelling which are frequently unilateral and asymmetric, as well as joint immobility and pain which is sometimes misdiagnosed as arthritis. In addition, long term effects can include obesity, skin changes, minor or severe infections, and even risk of lymphangiosarcoma if the lymphedema remains untreated. Cosmetic concerns also present psychological issues for many patients.
The symptoms of lymphedema gradually progress through three stages if left untreated. Stage I, or reversible lymphedema, is marked by swelling which can be temporarily reduced with simple elevation of the swollen arm or leg. However, more permanent relief can be achieved with certain physical therapy techniques. The swelling seen in stage I lymphedema also exhibits pitting of the overlying skin when it is depressed. Stage II is referred to as spontaneously irreversible lymphedema and is marked by an increase in fibrous tissue and progressive skin hardening. There can be frequent infections, swelling is increased, and the skin no longer pits when depressed. Simple elevation is no longer effective in reducing swelling at this stage. Stage III, or lymphostatic elephantiasis, shows an extreme increase in swelling in which the limb becomes columnar (loses definition of the knee and/or ankle). There are more extreme skin changes with increased hardening, and there can be large hanging skin folds. Stage III lymphedema can infrequently be associated with Stewart-Treves Syndrome, a highly malignant angiosarcoma.
What treatments are available for lymphedema?
Although there is presently no cure for lymphedema, treatment can delay or even prevent its progression to a more severe stage. Surgery is occasionally used to treat severe lymphedema. However it is not usually the treatment method of choice for patients with mild or even moderate symptoms. Non-surgical treatments are thought to provide greater relief with fewer complications. Since infections can intensify the symptoms of lymphedema, antibiotics may be prescribed in individuals with frequent infections to reduce this risk. Although some drugs can worsen the lymphedema symptoms, there are some drugs in clinical trials for lymphedema treatment. The Lymphovenous Canada website discusses some of these drugs and lymphedema treatments in more detail.
The most widely accepted treatment for lymphedema, complete decongestive therapy (CDT), involves five components which first establish drainage of lymph, and then maintain and improve the results of the initial intensive phase. The first component of CDT is decongestion or manual lymph drainage (MLD), which utilizes daily gentle massage and physiotherapy to improve the flow of lymph. The second component, compression therapy, then prevents the reaccumulation of fluid by tightly wrapping the limb following each MLD session. Once maximal reduction in swelling has been achieved, sometimes after one month of daily MLD, a special garment is custom-made to fit the limb. The next two components of CDT include meticulous skin care to avoid infections and daily remedial exercises performed while wearing the compression garment to improve muscle tone and help propel the flow of lymph. Lastly, the CDT therapist provides the patient with self care instructions for lifelong management of the condition.
The National Lymphedema Network website contains a list of diagnosis and treatment centers within the United States.
How is lymphedema diagnosed?
Clinical diagnosis by the symptomatic history of the condition as well as measurements and observation of symptoms is sufficient for diagnosis in approximately 90% of cases. In the remaining 10% symptoms can be non-specific making diagnosis more difficult. When necessary, CT or MRI scans can be used to image lymph nodes and show edema or fibrosis. Lymphangiography, an X-ray of the lymphatic system after injection of an oil-based contrast dye, is no longer used because it is thought to sometimes damage the remaining functional lymphatic vessels. Although it is costly, lymphoscintigraphy, an alternative imaging technique that utilizes a water-based dye, is now considered the safest and most accepted method of diagnostic testing for lymphedema. However, Dr. Eva Sevick at the University of Texas Health Science Center has also been working on a cutting-edge technology for imaging the lymphatics using near-infrared fluorescence instead of radiation.