Lymph Vessels and Lymphedema
by Robert Tallitsch, PhD | March 27, 2023
Video explaining lymph vessels and lymphedema using a real patient case example!
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Written by: Robert Tallitsch, PhD
Lymphedema refers to a chronic, severe, and prolonged tissue swelling resulting from a reduction in the reabsorption of intercellular fluid by the lymphatic system. Although the swelling can occur anywhere in the body, it typically occurs in the limbs. Lymphedema is a common complaint of cancer patients and individuals with high blood pressure. This Brain Builder will discuss the anatomy and function of the lymphatic system, as well as the symptoms, causes, and treatments for lymphedema.
Anatomy and Function of Lymphatic Vessels
As was discussed in a previous Brain Builder, The Lymphatic System and Lymphoma, lymphatic vessels are functionally a part of the cardiovascular system. The lymphatic system transports and monitors a fluid called lymph. Lymph is a protein-rich fluid containing interstitial fluid, macrophages, and lymphocytes.
Anatomy of lymphatic vessels: Lymphatic vessels carry lymph only from the periphery to the venous system. Anatomically, lymphatic vessels are wider in diameter, have thinner walls, and possess a greater permeability than the capillaries and other vessels of the cardiovascular system. As a result, high-molecular weight molecules, proteins, and cellular material move freely from the intercellular spaces into the lymphatic capillaries. The lymphatic vessels then carry this protein-rich fluid from the periphery towards the heart. Superficial lymphatic vessels join to form deeper lymphatic vessels termed lymphatic trunks. The lymphatic trunks empty into two large collecting vessels: the thoracic duct and the right lymphatic duct, which both empty into the venous circulation.
Fluid is moved from the capillaries of the cardiovascular system into the interstitial spaces due to hydrostatic pressure and osmotic differences between the cardiovascular system and the interstitial spaces. Considerably more fluid (approximately 4 liters per day) leaves the cardiovascular system on the arterial side than is reabsorbed back into the cardiovascular system on the venous side. Lymphatic vessels are essential for reabsorbing this excess fluid and protein and returning it to the cardiovascular system. Failure of the lymphatic system to return this excess fluid to the cardiovascular system results in the accumulation of excess fluid within the interstitial spaces — a condition referred to as edema.
The abnormal accumulation of protein-rich fluid due to a mechanical insufficiency of the lymphatic system is termed lymphedema. Lymphedema is more prolonged and considerably more serious than edema. Prolonged lymphedema may contribute to infection within the affected area, cause wounds to heal more slowly, and may impair mobility due to stiff and sore joints in the affected area.
There are two causes of lymphedema:
- Primary lymphedema is present in individuals who are born with improperly developed or improperly functioning lymphatic vessels. This condition may appear in infancy and is termed congenital lymphedema (Milroy’s disease). It may also appear during puberty or, rarely, later in life (typically before the age of 35) and is termed lymphedema praecox (Meige’s disease).
- Secondary lymphedema is more common, often resulting from trauma, high blood pressure, or cancer.
Prolonged, untreated blood pressure damages blood vessels. This allows the escape of proteins and fluid from the cardiovascular system into the peripheral interstitial spaces at a rate such that the lymphatic system cannot keep up, resulting in lymphedema.
The removal of lymphatic vessels during cancer surgery, or the damage of lymphatic vessels by radiation treatment during cancer treatment prevents or significantly alters the lymphatic vessels’ ability to reabsorb fluids and proteins. As a result, the accumulation of these proteins within the interstitial spaces changes the osmotic pressure of the interstitial space. This change increases the intracellular accumulation of even more fluid and proteins due to a physiological process termed positive feedback, resulting in worsened lymphedema that needs to be attended to by a physician.
Typical symptoms of lymphedema include:
- Swelling of a part of the body that increases over time.
- Skin appears thicker or leathery.
- Skin of the affected area feels tight and often has a tingling sensation.
Although there is no cure for lymphedema, patients may take several steps to reduce the swelling and prevent it from increasing in severity. Such steps would include increased exercise, use of compression sleeves or stockings, massage therapy, weight loss, or the use of a pneumatic pump. If the condition continues to worsen, surgery may be considered to help alleviate the problem.
Sadly, lymphedema is often a complication of cancer and cancer treatment and can be a continual reminder of the debilitating effects of an all-to-common and deadly disease.
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