Diaphragm Paralysis

Diaphragm paralysis is the loss of control of one or both sides of the diaphragm. This causes a reduction in lung capacity. Patients with diaphragm paralysis may experience shortness of breath, headaches, blue lips and fingers, fatigue, insomnia, and overall breathing difficulty.

The diaphragm, is a thin muscle (smaller than the width of a finger), which separates the chest and abdominal cavities.

Although the diaphragm performs most of the work, normal respirations also requires the simultaneous contraction of respiration accessory muscles (ie, scalene, parasternal portion of the internal and external intercostal muscles, sternocleidomastoid, trapezius).

• It is the most important muscle of ventilation & helps develop negative intrathoracic pressure to initiate ventilation. Innervated by cervical motor neurons C3-C5 via the phrenic nerves, these two nerves provide both sensory and motor function to the diaphragm.
  • Paralyzed Diaphragm does not cause the breathing to stop entirely as there are other muscles near the diaphragm which assist in breathing but the breathing in such cases is very labored since these other muscles are not as strong as the diaphragm.
    • The lungs themselves are not affected by paralysis, but the muscles of the chest, abdomen and diaphragm, can be. As the various breathing muscles contract, they allow the lungs to expand, which changes the pressure inside the chest so that air rushes into the lungs. This is the process of inhaling – which requires muscle strength. As those muscles relax, the air flows back out of the lungs.
  • If paralysis occurs in C3 or higher, the phrenic nerve is no longer stimulated and therefore the diaphragm does not function. This means mechanical assistance – usually a ventilator – will be required to facilitate breathing.
  • When the injury is between C3 to C5 (the diaphragm is functional), respiratory insufficiency still occurs. The intercostals and other chest wall muscles do not provide the integrated expansion of the upper chest wall as the diaphragm descends during inspiration.
• Whether the paralysis occurs in one (unilateral) or both (bilateral) sides of the diaphragm, all patients will experience some amount of reduction in lung capacity.
• Unilateral diaphragm paralysis is more common than bilateral disease and may be discovered incidentally on a chest radiograph.
  • Unilateral diaphragm paralysis commonly has no symptoms. However, if unilateral diaphragm paralysis occurs in patients with significant heart or lung disorders, symptoms can become evident.
• Bilateral diaphragmatic paralysis is a rare cause of respiratory failure that is poorly recognized and under-diagnosed.
  • In bilateral diaphragmatic paralysis, accessory muscles assume some or all of the work of breathing by contracting more intensely. An increased effort in the struggle to breathe may fatigue the accessory muscles and lead to respiratory failure.
  • The symptom onset is quite rapid and it is considered as an emergency situation requiring immediate treatment before the patient goes into respiratory distress which may in turn prove fatal for the patient.
  • Bilateral paralyzed diaphragm may be further complicated by the presence of certain other underlying illnesses which may cause respiratory failure and may prove fatal.

Causes and risk factors that compromise diaphragmatic function include:

• Any damage or injury to the phrenic nerve which controls the diaphragm
  • Direct damage or trauma to the phrenic nerve (the nerve that controls the function of the diaphragm), either from injury, surgery, radiation, tumor or bony protrusions.
    • Surgical trauma may occur in the following: Heart surgery, cervical/neck surgery, lung/heart/liver transplant
• Some viral infections or diseases, such as diabetes, can affect the phrenic nerve throughout the long course.
• Central neurological disorders such as a brain or brainstem stroke
• Critical illness/ventilator-induced diaphragm dysfunction
• ALS (commonly known as Lou Gehrig’s Disease), Multiple sclerosis, muscular dystrophy, poliomyelitis (Polio Fatalities), severe cervical spondylolysis, or other neuromuscular diseases
• Cancer in the Lung or in the lymph nodes, which can grow into or compress the nerve
• Connective-tissue diseases such as: Systematic lupus erythematosus/shrinking lung syndrome (Lupus)
• Birth trauma, which can injure the phrenic nerve in newborns and infants
• Spinal cord disorders and quadriplegia
• Neuropathic disease including thyroid and autoimmune disease,  Guillain-Barre syndrome, etc.

Symptoms of a paralyzed diaphragm:

• Patients with bilateral diaphragmatic paralysis may experience a 70-80 percent reduction in lung capacity while patients with unilateral diaphragmatic paralysis may experience a 50 percent reduction.
• Patients with diaphragmatic paralysis may experience a wide range of symptoms: from being asymptomatic, symptomatic only with exercise, or respiratory insufficiency and death.
• Symptoms of significant, usually bilateral diaphragm weakness or paralysis are shortness of breath when lying flat, with walking or with immersion in water up to the lower chest.
• Bilateral diaphragm paralysis can produce sleep-disordered breathing with reductions in blood oxygen levels.
• Newborns and children with unilateral diaphragmatic paralysis may experience more severe respiratory distress than adults, due to weaker muscles and a more compliant chest wall.
  • The newborn may have a weak cry or show signs of gastrointestinal distress, with frequent vomiting.
  • Children with bilateral diaphragmatic paralysis require immediate medical attention and ventilator intervention because the condition can be life-threatening.

Prognosis

• The prognosis for unilateral paralysis is good, providing there is no underlying significant pulmonary or cardiac disease. Some patients recover without medical intervention.
• The prognosis for bilateral paralysis also depends on the overall health of the patient, but surgery may be the best option for patients who continue to have a poor quality of life.
• Some lung conditions can be difficult to diagnose, and it is important for patients to seek medical attention from a specialist who is familiar with diaphragm weakness or paralysis.
• The cause of bilateral diaphragm paralysis goes unidentified in over two-thirds of cases
• With phrenic nerve injury following cardiac surgery, 80% recover in six months, and 90% recover in one year.
• When the diaphragm paralysis follows spinal cord injury, the paralysis may be permanent.

Morbidity

• The morbidity of the unilateral paralysis is mainly based on the underlying pulmonary functional status and the etiology of the paralysis. Because most cases of unilateral diaphragmatic paralysis are found incidentally during imaging studies, many patients have no symptoms. Diaphragmatic paralysis is more likely to affect the left hemidiaphragm. The patients with unilateral diaphragmatic paralysis that do have symptoms and decreased quality of life are those who have concurrent underlying lung diseases.
• Patients with bilateral diaphragmatic paralysis are usually symptomatic and, when symptoms are severe or in the presence of underlying lung pathology, may develop ventilatory failure without medical intervention.

Resources & Additional Reading

1. Avery Biomedical Devices - Diaphragm Paralysis - Problem & Treatment
2. Cedars-Sinai - Paralyzed Diaphragm
3. Medscape - Diaphragmatic Paralysis. By: Justine Gamache, MD. Updated 10 Oct 2018
4. Wikipedia - Phrenic nerve
5. UpToDate - Treatment of diaphragmatic paralysis. By: Bartolome R Celli, MD
6. NCBI: Journal of Clinical Medicine published online 5 Dec 2016 - Diaphragm Dysfunction: Diagnostic Approaches and Management Strategies. By: Bruno-Pierre Dubé and Martin Dres
7. Pain Assist - What is Paralyzed Diaphragm & How is it treated
8. [https://www.slideserve.com/issac/diaprhagmatic-paralysis
9. Christopher & Dana Reeve Foundation - How doew paralysis impact respiratory health?
10. Medscape - Diaphragmatic Paralysis.
11. Pulmonology Advisor - Neuromuscular Disorders Affecting the Thorax: Diaphragm Paralysis. By Parag Desai, Genard Criner