What is Diaphragm Disorders?
The diaphragm is a really important organ for mammals, including humans, because it’s the main muscle that we use for breathing. Diaphragmatic paralysis happens when this muscle loses its power, which can be because the muscle itself is weak or there’s damage to the nerves that supply it. How severe this paralysis is and whether it affects one side (unilateral) or both (bilateral) can determine how much it affects a person. Some people may not have any symptoms at all, while others may rely on a ventilator to help them breathe.
So, what’s the diaphragm? It’s a dome-shaped structure made of muscle and fibrous tissue. It’s positioned between the chest and tummy compartments within the body and acts as the floor of the chest and the roof of the abdomen. Although it looks like one piece, it actually works as two separate units, the right and the left, each having its own blood and nerve supply. The muscle part of the diaphragm comes from three muscle groups. The central part is composed of strong, cord-like structures known as tendinous ligaments. The diaphragm shape changes as we breathe, flattening and expanding the chest cavity to draw air in when we inhale, and relaxing and constricting the cavity to push air out when we exhale.
Though other muscles in the chest can help with breathing, the diaphragm is the most important. If it’s weak, it can affect our ability to breathe. Paralysis of both sides of the diaphragm can seriously affect a person’s ability to breathe. But, if only one side is weakened, a person may not display symptoms due to the other side of the diaphragm and other muscles compensating. The diaphragm also helps in important bodily functions like vomiting, urinating, and defecating, by increasing the pressure in the abdomen. It also stops regurgitation or bringing stomach content back up the food pipe.
The diaphragm also has various openings that allow parts of the body to pass from the chest to the tummy and vice versa. These openings allow key veins and other structures to move between these areas of the body.
Normally the diaphragm works automatically, although we can consciously control it if needed. This is possible because of two nerves originating from nerves in the neck region which innervate or supply the diaphragm. These control both feeling and movement functions. The diaphragm’s blood supply comes from specific arteries, and these are also responsible for draining away waste blood.
What Causes Diaphragm Disorders?
Diaphragmatic palsy, or weakness, can be due to either the muscle of the diaphragm weakening and shrinking, or damage to the phrenic nerves, which are the nerves controlling the diaphragm. It’s more common for one side of the diaphragm to be affected than both. Depending on the cause, this weakness can either come and go, or be permanent.
There are five main reasons why the diaphragm might become weak:
1) Trauma: This is the most common reason for diaphragmatic weakness. Damage can occur to the phrenic nerve during surgery or injury, leading to weakness. Heart bypass surgery is most often associated with this, with a 20% chance of diaphragmatic weakness. The phrenic nerve can be damaged during this surgery due to chilling of the heart and surrounding tissues. Procedures involving the area between the lungs, esophagus surgeries, or lung transplants also carry risk of diaphragmatic weakness. Additionally, injuries from penetrating objects or gunshots can cause nerve damage.
2) Compression: If something large, like a tumor or lung cancer, is close to the phrenic nerve in the chest area, it can press on the nerve and cause it to lose function. About 5% of lung cancer cases show evidence of this. Other causes can be an enlarged aorta, goiter in the chest area, and neck bone diseases.
3) Neuropathic: Damage to the phrenic nerve can occur due to various nerve-related diseases like diabetic nerve damage, certain muscle diseases, multiple sclerosis, and chronic inflammatory nerve disease.
4) Inflammatory: Some diseases can cause inflammation of the phrenic nerve or diaphragm, leading to weakness. These include viral infections such as HIV, West Nile virus and polio, bacterial infections like Lyme disease, and non-infectious conditions like sarcoidosis and amyloidosis.
5) Idiopathic: In about 20% of cases, no clear reason is found even after thorough investigations. When no cause can be found, the condition is referred to as “idiopathic”.
Risk Factors and Frequency for Diaphragm Disorders
About 20% of people may experience diaphragmatic palsy after undergoing heart surgery.
Signs and Symptoms of Diaphragm Disorders
Diaphragmatic weakness can have various symptoms, which depend on what is causing the weakness and how long the patient has had the condition. Symptoms can change depending on whether it affects one or both sides of the diaphragm.
Often, people with weakness on one side of the diaphragm don’t even know they have the condition until it’s discovered during a medical exam for another reason. However, about one in three of these people do experience shortness of breath when they exert themselves. Those who also have heart or lung conditions might feel short of breath even when they are at rest. Typically, they also have a reduced ability to exercise and lower levels of oxygen in their blood when they are at rest.
People with weakness on both sides of the diaphragm generally feel short of breath to different degrees. This can range from feeling winded after exertion to feeling winded even when at rest. Lying down can make the condition worse, leading some to feel short of breath when they are in a reclining position. Over time, as their diaphragm function deteriorates, they may gradually develop a condition where they breathe too slowly or shallowly, leading to high carbon dioxide levels in their blood and potentially right heart failure. Shortness of breath along with high carbon dioxide and low oxygen levels are more severe when they are asleep.
Testing for Diaphragm Disorders
If your doctor thinks you might have a weak diaphragm, they will likely order several types of tests. One common test is a chest X-ray. The reason for this is that the position of your diaphragm can give doctors clues about its health. Your diaphragm is normally positioned slightly higher on the right side. If the diaphragm on one side is weak, it will be pulled higher into the chest due to the negative pressure inside. So, if the diaphragm appears at a higher level than normal, it might mean that it’s weak or paralyzed. By looking at an X-ray of your chest, doctors can detect diaphragm weakness in about 90% of cases.
Another useful test for diaphragm weakness is a fluoroscopic test. This is a type of imaging that shows the diaphragm moving in real-time. Normally, when you breathe in and out, both sides of your diaphragm move downward and then back up again. But if one side of your diaphragm is weak, it may move less or even not at all. Sometimes, the weak side might even move in the opposite direction!
An ultrasound of your chest can also help. During this test, a doctor will look for signs of diaphragm weakness, such as a lack of movement or movement in the wrong direction.
Doctors can also use a CT scan of your chest to check for any diseases that might be causing your diaphragm to weaken. However, a CT scan might not show diaphragm weakness clearly.
Pulmonary function tests can show how well your lungs and diaphragm are working together. Your diaphragm plays a major role in your ability to breathe, so if it’s weak, it can greatly affect your lung function. For instance, the amount of air you can force out of your lungs in one breath (known as “forced vital capacity”) could drop by half if one side of your diaphragm is weak, and even more if both sides are weak. These tests also check how lying flat affects your breathing.
Lastly, electrophysiological tests can be used to study the nerves that control your diaphragm. They can help determine if the weakness is due to a nerve issue or a problem with the diaphragm itself.
Treatment Options for Diaphragm Disorders
If the weakness of the diaphragm continues, there are three main ways to treat it.
The first method is called noninvasive positive-pressure ventilation, which applies pressure to the airways. This pressure helps to stabilize the movements of the diaphragm and support the muscles that assist with breathing. This technique is usually used at night, as more breathing problems can occur when lying down. If needed, it can also be used during the day. In severe cases, if masks are not tolerated, an option is to create a small opening in the neck, known as a tracheostomy. If this setting is still not comfortable, then a machine that helps with breathing, a mechanical ventilator, can be used. This method can be especially beneficial when the paralysis of the diaphragm is temporary after surgery.
The second strategy is a surgical procedure known as diaphragmatic plication. It corrects the disadvantage created by the paralyzed diaphragm in the chest cavity. This complex procedure effectively eases the symptoms and improves lung function. It can be carried out through a traditional open chest surgery or a less invasive method using a camera, known as video-assisted thoracic surgery.
The third method is diaphragmatic pacing, which involves using an electrical device to stimulate the phrenic nerve that controls the diaphragm. This can be useful in cases where only one side of the phrenic nerve is paralyzed. The electrical device generates power in the diaphragm through stimulation. This device can be placed in the neck or close to the diaphragm, depending on where the damage to the phrenic nerve has occurred.
What else can Diaphragm Disorders be?
If you experience a decrease in oxygen levels in the lungs (alveolar hypoventilation), it may be caused by numerous conditions. These include issues with nerves in your spinal cord that control your muscles (anterior horn cell or neuromuscular junction disease), brain bleeding (cerebral haemorrhage), neck bone fractures (cervical fracture), or breaking the bone that surrounds and protects your spinal cord (cervical spine fracture).
Likewise, decreased flexibility in your lungs (decreased pulmonary compliance), Guillain-Barre syndrome (a neurological disorder), Myasthenia gravis (a muscle weakness disease), damage to the nerves in your peripheral nervous system (peripheral neuropathies), or the forming of fibrous tissues in your pleural cavity (pleural adhesions) may also lead to this condition. Understanding which condition is causing decreased oxygen levels is essential to formulating an effective treatment plan.