Many ailments originate from excess fluid in tissues, e.g., due to insufficient or damaged drainage of fluid from the tissue. As a result, this fluid causes elevated pressure in the tissue, which may result in discomfort and/or tissue damage. Examples of tissues prone to this problem are the brain, kidneys, lymph nodes, and eyes.
For hydrocephalus (i.e., the abnormal accumulation of cerebrospinal fluid in the ventricles of the brain), a common treatment approach is to use a shunt, which includes a drainage tube and a valve that controls the volume and rate of cerebrospinal fluid outflow from the brain to another part of the body (e.g., the abdomen).