What is lymphedema?

Lymphedema is the accumulation of tissue fluid (lymph) in the extremities caused by insufficient muscle activity. In ALS, lymphedema of the hands, forearms, and lower legs is a common symptom. In a healthy body, there is a balance between the supply of blood to the extremities (via the arteries) and the return of blood (after oxygen and other metabolic byproducts have been utilized) back to the heart (via the veins).

Blood flow is propelled by muscles within the arteries (perceived as the “pulse” of the arteries). The muscles of the returning blood vessels (veins) are much weaker. The return flow of blood depends on muscle activity in the extremities, which helps “squeeze” the veins toward the body (venous-muscle pump). If the muscles are weak, blood flow through the arteries (driven by the arteries’ own muscles and the “pulse”) continues unchanged, while the outflow of blood is no longer sufficient due to paralysis and the resulting reduction in the venous-muscle pump. As a result, an imbalance develops between the inflow and outflow of blood, leading to altered pressure conditions in the tissue and an accumulation of interstitial fluid.

Lymphedema can lead to painful skin tightness and add extra weight to the already weakened limb. Lymphedema can be reduced through lymphatic drainage, wearing compression stockings, and elevating the limbs. Lymphedema is a common symptom in cases of severe paralysis and an important treatment goal in physical therapy and assistive device provision.