Disorders of the central lymphatic drainage system

What are lymphatic drainage disorders?

Everyone knows that there are veins filled with blood in our body. Many people are also familiar with what these blood vessels are called – the arteries lead away from the heart into the body, the veins lead back to the heart. What is less well known is that we have a second network: the lymphatic system. As an important part of the immune system, it produces defense cells against pathogens. They are transported in a watery, slightly cloudy body fluid called lymph.

If this transport – the lymphatic drainage – is disrupted, swelling, inflammation and other complaints can occur. Various treatment options are available for lymphatic drainage disorders to ensure that the accumulated lymph can flow freely again.

How does the lymphatic system work?

Unlike the blood system, the lymphatic system does not form a circulatory system. It is not a closed system, but has a beginning and an end. The net-like, widely branched structure consists of thin veins or ducts called lymph vessels. At their beginning, at various points in the body tissue, these pathways are still very fine and are called lymph capillaries. Later, the diameter of the lymph vessels increases.

Lymph fluid (lymph) flows in the lymph vessels and moves towards the heart. As a powerful pump, the heart itself ensures blood flow, but not the transport of colorless lymph. It moves rather slowly and is driven, among other things, by movements of the skeletal muscles and by pressure differences during breathing.

The lymph vessels of the arms, legs and head form the peripheral lymphatic system. These lymph vessels flow deep inside the body next to the vertebral column into the central lymphatic system, which also collects the lymph from the organs in the abdominal cavity. Fats and proteins that are absorbed in the intestine stain the lymph in the abdominal cavity a whitish color and the fluid is then called chyle .

Lymph nodes are the cleaning terminals of the lymph fluid

The lymphatic system is interrupted in several places – from millimeter-sized to centimeter-sized lymph nodes, of which there are several hundred in the body. Inside it, the lymph fluid is filtered and purified because it contains cell residues, bacteria, toxins and other waste that the body does not need.

This cleaning work in the lymph nodes is carried out by defense and scavenger cells, for example lymphocytes, which belong to the white blood cells. They neutralize or destroy all unwanted foreign bodies in the lymph.

Lymphatic organs produce defense cells

Lymphocytes do not develop, mature and multiply in the lymph nodes, but in certain places in the body called lymphatic organs. These include the bone marrow, the spleen, the thymus gland and the tonsils.

At the end, near the heart, all the lymphatic vessels flow into large veins, including the largest lymphatic vessel in the body, known medically as the thoracic duct. When it enters the veins, the purified lymph and the lymphocytes it contains pass into the blood.

In order for this extensive and effective purification system of our body to function smoothly, the lymph fluid must be able to flow undisturbed and, if possible, remain in constant motion. Every day, around two to four liters of lymph are transported through the lymph vessels.

Defective lymph channels can lead to health problems

If a lymphatic duct is injured, a leak occurs (medically known as a lymph leak ) from which lymph escapes and enters the surrounding tissue. Here the lymph fluid makes room for itself by causing a swelling, a so-called lymphocele or seroma. If the lymph fluid accumulates either due to a congenital malformation of the lymphatic system or the interruption of lymph drainage, e.g. due to an operation, lymphoedema develops.

The lymph that escapes through the leakage can also enter a cavity in the body; in this case it is referred to as an effusion. Another lymphatic drainage disorder occurs when a lymph channel is squeezed or otherwise blocked, resulting in lymph congestion .

In all these cases, the lymphatic drainage disorder causes fluid to accumulate in the affected part of the body. If it cannot drain away for a long time, this usually results in damage to health.

Edema forms relatively frequently on an arm or leg. In addition to such impairments in the extremities, accumulated lymph can also lead to health problems in the center of the body in rarer cases. This is referred to as a “central” lymphatic drainage disorder.

Chylothorax and Chylakos

In chylothorax, chyle, a milky-white fluid from the lymphatic system, accumulates in the chest. If this occurs in the abdominal area, it is called chylaskos. This fluid consists mainly of fat, proteins and lymphocytes and is normally transported into the bloodstream via the thoracic duct. Causes can be injuries to the thoracic duct, tumors, infections or congenital malformations.

Treatment depends on the cause and ranges from conservative measures such as dietary changes and drainage to surgical interventions. In some cases, interventional radiological procedures or medication can also be used to promote chyle resorption.

Protein-losing enteropathy

Protein-losing enteropathy (PLE) is a medical syndrome in which proteins are lost through the intestines, leading to a deficiency in the body. As proteins are essential building blocks for many bodily functions, their loss can have serious health consequences. In addition to inflammatory bowel diseases, this can often be caused by central lymphatic drainage disorders of the bowel.

The treatment of PLE focuses on combating the underlying disease and restoring protein levels in the body through an adapted diet and, if necessary, reconstruction of the central lymphatic drainage.

Causes: How does a central lymphatic drainage disorder develop?

It is not always possible to determine the cause of a central lymphatic drainage disorder. Congenital malformations of the lymphatic system can affect infants and children. Injuries are also a possible cause; they can occur accidentally during a surgical procedure, for example.

Another possible cause of impaired lymph drainage in central areas of the body is other diseases. Several of these can lead to a chylothorax:

• Lymphangioleiomyomatosis (LAM). Genes and hormones are involved in the development of this rare lung disease; almost only women are affected. Chylothorax can occur as a result.
• Gorham-Stout disease (GSD) is a very rare disease in which lymph vessels enlarge abnormally and bones are destroyed.

Surgical procedures, tumors, injuries or constrictions of the lymphatic system in the abdominal cavity are all possible causes of chyl ascites.

Pericardial effusion can be caused by injuries and malformations of the lymphatic system, among other things. In about half of the cases, however, the cause of a chylopericardium remains unclear. It often occurs together with a chylothorax.

Possible causes of intestinal lymphangiectasia include a congenital malformation of the lymphatic vessels, but also gastrointestinal infections, intestinal inflammation or tumors.

Diagnosis: How do you recognize a central lymphatic drainage disorder?

Doctors use various methods to determine whether impaired lymphatic drainage is the cause of health complaints. These provide more precise information about the lymph vessels and lymph nodes in the affected body region. In the case of a central drainage disorder, the suspicious lymph channels and nodes are usually located in deeper regions of the body. Unlike lymph nodes in the neck, for example, they are difficult to access and cannot be felt.

However, modern diagnostic possibilities also allow insights into central parts of the lymphatic system:

• Conventional lymphography (also known as lymphangiography ) visualizes lymph vessels and lymph nodes using X-rays. In this imaging procedure, a dye or contrast agent is injected into the lymphatic system. This allows you to see whether – or at which point – the lymph fluid is accumulating.
• Magnetic resonance lymphangiography (MR lymphangiography) is a modern procedure that does not require X-rays. It also visualizes the lymph vessels and lymph nodes and makes disturbances in the lymphatic drainage visible. Dynamic MR lymphangiography makes this possible with particular precision: in contrast to the individual images of a static angiography, numerous images taken at short intervals (“dynamic”) show the flow velocity and direction of the lymphatic fluid – and thus possible disturbances in the lymphatic drainage.

Therapy: How are lymphatic drainage disorders treated?

Initially, attempts are made to regulate the lymph flow with medication or a specific diet. Leaks can sometimes be sealed by sclerosing them. In many cases, however, surgery is the only effective treatment for a central lymphatic drainage disorder. However, the surgical site deep in the body is difficult to reach and the lymph vessels are tiny – sometimes only half a millimeter in diameter.

Surgery on the central lymphatic system is therefore very difficult using conventional instruments. At the University Hospital Zurich (USZ), we therefore also use a microsurgery robot to perform procedures on the central lymphatic system. This procedure was performed for the first time worldwide at the USZ in 2023. With success: the robot, called Symani, is able to penetrate deeper body regions with its microsurgical instruments and work there with high precision.

Whether with robotic assistance or in the conventional way – in lymphatic surgery, doctors use microsurgical techniques that are sometimes combined with each other:

• Lymphovenous anastomosis (LVA). The aim is to establish a direct connection between the lymphatic vessel and the vein. This allows the lymphatic fluid to drain via the central venous system and the lymph congestion dissolves. Disturbed lymph drainage channels are bypassed in this way.
• Vascularized lymph node transfer (VLNT). Functioning (vascularized, i.e. supplied with blood) lymph nodes are removed from an easily accessible part of the body, for example from the armpit. The surgeon moves the lymph nodes to a location where there is a lymphatic drainage disorder so that they can start working here.