The diaphragm is a muscle that separates the chest and abdominal cavities; it is controlled by the phrenic nerves.
Diaphragmatic paralysis is uncommon. In patients where one side of the diaphragm is paralyzed, people usually have no symptoms unless they have another reason for shortness of breath (asthma, emphysema, etc.). Because a paralyzed diaphragm is higher than usual, it compresses the lung and prevents the patient from taking a normal breath. Also, when a patient breaths, the diaphragm usually moves down to pull air in to the lung. Paradoxically, a paralyzed diaphragm moves up and further compresses the lung
- Shortness of breath
- Orthopnea (shortness of breath worse lying down and better sitting up)
There are many situations where the phrenic nerve does not work because it was invaded, compressed, cut, including:
- Surgical trauma, such as unintentional injury after a heart or neck procedure
- In newborns and infants, birth trauma
- Neurological diseases, such as ALS, multiple sclerosis, muscular dystrophy, Guillain-Barre syndrome
- Spinal cord disorders and quadriplegia
- Chest Surgery where the phrenic nerve is cut or removed to remove a tumor
- Chronic pneumonia, bronchitis or cardiac arrhythmias
- Thyroid and autoimmune disease
- Pulmonary function testing while lying down and again while upright.
- Lung capacity is often reduced about 10 percent when a person is lying down
- Patients with bilateral diaphragmatic paralysis may experience a 70 to 80 percent reduction in lung capacity while patients with unilateral diaphragmatic paralysis may experience a 50 percent reduction
- FEV 1 = 60-70% of normal
- Total Lung Capacity: 60-70% of normal
- Chest X-rays (see figure): the diaphragm is higher than usual and compresses the lung or an upright, inspiratory chest radiograph
- Sniff Test: With fluoroscopy, the radiologist watches he diaphragm as the patient sniffs. A normal lung moves down and the lung expands. A paralyzed lung moves up to compress the lung.
- Phrenic nerve stimulation testing shows the nerve does not work
- Computed tomography (CT) scanning of the thorax shows the diaphragm is high and is done to make sure there is no tumor on the phrenic nerve
- Magnetic resonance imaging (MRI) to determine if there is an underlying condition involving the spinal column or nerve roots
Treatment begins with an evaluation of the overall health of the patient, how much the shortness of breath impacts the patient’s life, and any underlying cause for the paralysis. This is an elective operation so the symptoms need to be bad enough to justify the operation.
The prognosis for unilateral paralysis is quite good, providing there is no underlying pulmonary disease. Sometimes, patients recover without any 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.