AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

The respiratory system functions as a vital pump that moves air in and out of the lung gas-exchange units. The respiratory pump consists of central respiratory centers, the spinal cord, peripheral nerves, neuromuscular junctions, and respiratory muscles.

The most important part of the respiratory muscles is the dome-shaped diaphragm, which is innervated by cervical motor neurons C3-5 via the phrenic nerves. Diaphragm contraction decreases intrapleural pressure during inspiration, expands the rib cage, and thereby facilitates movement of gases into the lungs.

Pathophysiology

Diaphragmatic paralysis can involve either the whole diaphragm (bilateral) or only one leaflet (unilateral).

Although the diaphragm performs most of the work, normal ventilation also requires the simultaneous contraction of respiration accessory muscles (ie, scalene, parasternal portion of the internal and external intercostal muscles, sternocleidomastoid, trapezius). In bilateral diaphragmatic paralysis, respiration 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 ventilatory failure.

Frequency

United States

Incidence is unknown.

Mortality/Morbidity

The goal of care is to provide ventilatory support to patients with bilateral diaphragmatic paralysis to avoid progressive respiratory failure and death. Unless the prognosis of unilateral diaphragmatic paralysis is complicated by a potentially fatal comorbid illness, death from respiratory insufficiency does not occur.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Bilateral diaphragmatic paralysis is characterized by profound abnormalities of pulmonary and respiratory muscle function. Patients develop severe restrictive ventilatory impairment, and the vital capacity and total lung capacity frequently are below 50% of predicted for that patient. Lung capacity is reduced further when the patient assumes the supine position. Symptoms depend on whether the paralysis is unilateral or bilateral, how rapid the paralysis occurs, and the presence of underlying pulmonary disease.

• Unilateral diaphragmatic paralysis
• • Unilateral diaphragmatic paralysis is often discovered incidentally in patients undergoing chest radiography for some other reason.
  • Patients usually are asymptomatic at rest but experience dyspnea on exertion and have a decrease in exercise performance.
  • If the patient has an underlying lung disease, dyspnea may occur at rest.
  • Some patients may develop orthopnea, which is less intense than bilateral diaphragmatic paralysis.
• Bilateral diaphragmatic paralysis
• • Patients typically present with respiratory failure or dyspnea (may be misinterpreted as a sign of heart failure) that worsens in the supine position. Tachypnea and rapid shallow breathing occur when the patient adopts the recumbent position.
  • Patients also report anxiety, insomnia, morning headache, excessive daytime somnolence and fatigue, and poor sleep habits.

Physical

Physical examination findings depend on whether the paralysis is unilateral or bilateral. Generally, a breathing pattern of paradoxical abdominal wall retraction during inspiration occurs. The physician can evaluate the patient further by palpating under the costal margin and feeling for the descending hemidiaphragms during inspiration.

• Unilateral diaphragmatic paralysis
• • Patients reveal dullness to percussion and absent breath sounds over the lower chest on the involved side.
  • Excursion on the involved hemithorax is decreased when compared to the healthy side.
• Bilateral diaphragmatic paralysis
• Patients report morning headaches, confusion, and signs of cor pulmonale.
• Chest examination reveals limitation of diaphragmatic excursions and bilateral lower chest dullness with absent breath sounds.
• Patients are tachypneic and use accessory respiration muscles.
• The diagnostic finding is a paradoxical inward movement of the abdomen with inspiration.

Causes

Diaphragmatic paralysis can be unilateral or bilateral. The physician can classify the causes further according to the type of paralysis.

• Unilateral diaphragmatic paralysis
• • Tumor nerve compression (approximately 30% of patients)
  • Lesions adjacent to a phrenic nerve (eg, pneumonia, pleurisy, aortic aneurysm, substernal goiter, neoplasms)
  • Natural or surgical trauma, herpes zoster, and cervical spondylosis
  • Trauma (common and may result from thoracic surgery, manipulation of cervical spine, central venous catheterization, open heart surgery): Phrenic nerve injury resulting from blunt trauma is unusual and may closely mimic diaphragmatic rupture. In a case report, left phrenic nerve injury and pericardial injury were found. Diaphragmatic plication was performed through a miniature left posterolateral thoracotomy (Ulku, 2005).
  • Herpes zoster, infection, vasculitis, and diabetes mellitus (may be caused by peripheral neuropathy of phrenic nerve)
  • Idiopathic
• Bilateral diaphragmatic paralysis
• Tumor nerve compression (approximately 30% of patients)
• Lesions adjacent to a phrenic nerve (eg, pneumonia, pleurisy, aortic aneurysm, substernal goiter, neoplasms)
• Natural or surgical trauma, herpes zoster, and cervical spondylosis
• Trauma (commonly may result from thoracic surgery, manipulation of cervical spine, central venous catheterization, open heart surgery)
• Herpes zoster, infection, vasculitis, and diabetes mellitus (may be caused by peripheral neuropathy of phrenic nerve)
• Thoracic and cervical spine surgery
• Blunt chest trauma
• Multiple sclerosis
• Anterior horn cell disease
• Peripheral neuropathy
• Muscular dystrophy
• Myopathy

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

The following diagnoses may be difficult to differentiate from bilateral diaphragmatic paralysis:

• Alveolar hypoventilation is caused by brain stem or high cervical spine disease. Patients have normal respiratory muscle strength and can voluntarily hyperventilate to lower PaCO₂.
• Anterior horn cells and neuromuscular junction diseases may be difficult to differentiate from phrenic nerve dysfunction.

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Arterial blood gas analysis
• • This study demonstrates hypoxemia in bilateral diaphragmatic paralysis. Hypoxemia develops from atelectasis and ventilation-perfusion mismatching.
  • Progressive hypercapnia also develops with disease progression.

Imaging Studies

• In contrast to bilateral disease, physicians can usually diagnose unilateral paralysis with only radiographic studies.
• Chest radiography is as follows:
• • This study reveals elevated hemidiaphragms, small lung volumes, and atelectasis.
  • In unilateral diaphragmatic paralysis, chest radiographic findings strongly suggest the diagnosis (see Images 1-2).
• Fluoroscopy is as follows:
• • Because accessory muscle contraction may create the appearance of diaphragmatic movement, this study may mislead the physician when diagnosing bilateral diaphragmatic paralysis (see Image 3).
  • Fluoroscopic sniff test (in which paradoxical elevation of the paralyzed diaphragm is observed with inspiration) can confirm chest radiographic findings regarding unilateral diaphragmatic paralysis (see Image 4).
• Computed tomography scanning of the chest: This study may be indicated in certain patients to evaluate for potential causes of diaphragmatic paralysis that are due to mediastinal pathology.
• Magnetic resonance imaging of the neck: This study may be indicated in certain patients to determine the presence of pathologic conditions involving the spinal column or nerve roots that are causing diaphragmatic paralysis.
• Ultrasonography
• • The M mode ultrasonography is the latest method to evaluate the paralyzed diaphragm. The paralyzed side shows no active caudal movement of the diaphragm with inspiration and abnormal paradoxical movement (ie, cranial movement on inspiration) particularly with the sniff test.
  • It is a relatively simple and accurate test for diagnosing paralysis of the diaphragm in the adult population, and it can be performed at the bedside and can be easily repeated if paralysis is not thought to be permanent (Lloyd, 2005).

Other Tests

• Pulmonary function and arterial blood gas tests
• • Measuring the vital capacity in the upright and supine positions is the most important pulmonary function test.
  • Normally, vital capacity in recumbency decreases by 10%. In unilateral paralysis, the vital capacity shows a decrease to 70-80% of the predicted level. The decrement is usually slightly more significant in the supine position.
  • In contrast, patients with bilateral diaphragmatic paralysis show a 50% decrease in vital capacity when they are supine. This decrease is from cephalad displacement of abdominal contents.
• Electromyography
• Record diaphragmatic electromyography (EMG) with other surface or esophageal electrodes; however, EMG has a limited role in unilateral diaphragmatic paralysis.
• EMG may reveal a neuropathic or myopathic pattern, depending on etiology. Phrenic nerve stimulation at the neck can differentiate between neuropathy and myopathy.
• Measurement of transdiaphragmatic pressure
• • This is the criterion standard for diagnosis.
  • This test is performed by placing a thin-walled balloon transnasally at the lower end of the esophagus, allowing reflection of the changes in pleural pressure. Then, a second balloon manometer is placed in the stomach to reflect changes in intra-abdominal pressure.
  • The difference between the two is the transdiaphragmatic pressure. Consult with an expert to perform and interpret these tests. This measurement can help differentiate diaphragmatic paralysis from other causes of respiratory failure.
• Maximal inspiratory pressures: Patients with diaphragmatic dysfunction and paralysis have a decrease in maximal inspiratory pressures (PI max). These patients cannot generate high negative inspiratory pressures. Therefore, the Pl max in these patients is less negative than -60 cm H₂O.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

The diaphragm, the most important muscle of ventilation, develops negative intrathoracic pressure to initiate ventilation. Overt respiratory failure develops if the involvement is severe. Paralysis can be unilateral or bilateral from systemic diseases or from diseases primarily affecting the diaphragm. Unilateral diaphragmatic paralysis is usually well tolerated when no underlying lung or ribcage pathology is present. In respiratory diseases, unilateral diaphragmatic paralysis can cause dyspnea and hypoxemia. Bilateral diaphragmatic paralysis is usually symptomatic and when severe or in the presence of underlying lung pathology may result in ventilatory failure. Rarely over a prolonged period, several patients with unilateral or bilateral paralysis will spontaneously improve. Outcome can be improved in patients with symptoms or ventilatory failure with noninvasive ventilation or, in selected cases of unilateral paralysis, surgical plication of the diaphragm.

• Unilateral diaphragmatic paralysis
  • Most patients are asymptomatic and do not require treatment; however, consider diaphragm plication in patients with dyspnea that is disproportionate to the degree of physical activity or severity of lung disease.
  • Pursue the possibility of an underlying pulmonary disorder in symptomatic patients and, if found, treat aggressively.
• Bilateral diaphragmatic paralysis
  • Treatment depends on the etiology and severity of the paralysis.
  • Treat most patients with ventilatory support.
• Role of sleep studies
  • These studies are required for patients who are being considered for negative pressure ventilation because the condition may worsen upper airway obstruction during sleep. Consideration of positive-pressure ventilation lessens the need for screening sleep studies.
  • Most patients with mild-to-moderate diaphragmatic weakness maintain daytime gas exchange but worsen during sleep. Sleep studies and ventilatory assisted device treatments can identify this condition.
• Ventilatory support
  • Patients with bilateral diaphragmatic paralysis have progressive ventilatory failure. The therapeutic tool of choice for symptomatic patients is noninvasive positive-pressure ventilation.
  • Patients in whom nasal or oral positive-pressure ventilation is unsuccessful may need other forms of noninvasive ventilation (eg, negative pressure cuirass, pulmonary wrap, rocking bed, positive-pressure pneumobelt).
  • Reserve a tracheostomy with positive-pressure intermittent or permanent ventilation for patients with life-threatening disease or a diagnosis of high quadriplegia.
• Diaphragmatic pacing
  • Phrenic nerve pacing may be considered in patients who have intact phrenic nerve function and no evidence of myopathy. The ideal patient is one with high quadriplegia without intrinsic lung disease.
  • Data from centers with experience in this procedure show that approximately 50% of patients improve enough to discontinue ventilatory support.
• • Definitely perform a tracheostomy on these patients because they invariably develop upper airway obstruction.

Surgical Care

• Diaphragmatic plication
• • Stabilization from surgical plication of the paralyzed diaphragm provides good results in selected patients. Following plication, the paralyzed diaphragm does not paradoxically move cephalad into the thorax during inspiration and, therefore, improves ventilation to the affected site. Furthermore, the procedure also favors the healthy diaphragm, which now performs less work.
  • Improvements in lung mechanics and exercise performance follow this procedure. In a select group of patients, diaphragmatic plication decreases breathlessness, improves vital capacity by 10-20%, and improves PaO₂ by 10%.
  • In a recent surgical series, the mean forced tidal volume improved dramatically from 216 to 415 mL after plication, and it was possible to discontinue mechanical ventilation from 2 to 12 days after plication. Diaphragmatic plication is a useful procedure for treatment of diaphragmatic paralysis in adults as well in children (Kuniyoshi, 2004).
  • Plication of the diaphragm through a thoracotomy is known to provide excellent long-term results. Plication can also be performed via video-assisted thoracoscopic surgery (VATS). Case reports have been published where patients with postoperative left phrenic nerve paralysis underwent plication of the diaphragm using VATS and achieved total relief of all symptoms.

FOLLOW-UP

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Complications

• Phrenic nerve injury commonly occurs from cold cardioplegia or mechanical stretching during open-heart surgery.

Prognosis

• Unilateral diaphragmatic paralysis
• • Depending on the etiology of the diaphragmatic paralysis, the prognosis of unilateral disease usually is excellent unless the patient has significant underlying pulmonary disease.
  • Patients develop compensatory mechanisms, and patients with phrenic injuries may recover fully or partially.
  • At times, patients may spontaneously recover from idiopathic disease. Patients who do not recover from unilateral diaphragmatic dysfunction generally lead relatively normal lives.
  • Patients generally are asymptomatic.
  • Dyspnea may develop during exercise or in other situations, leading to increased ventilatory demands.
• Bilateral diaphragmatic paralysis
• • Prognosis depends on the nature of the underlying disease.
  • Patient diaphragm function may recover if nerve injury is not permanent, while other patients may require long-term ventilatory support.
• Surgical considerations: Although not proven in randomized trials, patients who continue to be dyspneic or continue to lead a poor quality of life can be considered for surgical plication.

MISCELLANEOUS

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• In patients with nontraumatic bilateral diaphragmatic paralysis, the diagnosis often goes unrecognized until the patient presents with cor pulmonale or cardiorespiratory failure.
• Unilateral diaphragmatic paralysis often is asymptomatic and is recognized as unilateral elevation of diaphragm on chest radiography.

Special Concerns

• Diaphragmatic dysfunction following cardiac surgery
• • Diaphragmatic dysfunction often occurs postoperatively in patients undergoing cardiac surgery. This has been attributed to pleurotomy in order to harvest internal mammary artery (IMA) grafts, which results in greater chest wall and parenchymal trauma, greater pain, and impairment of cough and deep breathing. In addition, IMA dissection may reduce blood supply to ipsilateral intercostal muscles and cause mechanical injury to the phrenic nerve.
  • In the past, studies have confirmed phrenic nerve injury from cold-induced injury during myocardial protection, although presently, most centers use warm cardioplegia.
  • The consequences of post–cardiac surgery diaphragm dysfunction vary from asymptomatic radiographic abnormality to severe pulmonary dysfunction requiring prolonged mechanical ventilation and increased morbidity and mortality.
  • In one study, incidence of diaphragmatic dysfunction was 11% (5 of 44 patients), and only 1 patient had phrenic nerve palsy.
  • Most patients with post–cardiac surgery diaphragmatic dysfunction improve with conservative measures such as chest physiotherapy, prevention and treatment of pneumonia, treatment of underlying chronic obstructive pulmonary disease (if present), and overall care. Rarely, diaphragmatic plication may also be required in such patients.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Acute unilateral left diaphragmatic paralysis in a patient with moderately severe chronic obstructive pulmonary disease. The patient previously was asymptomatic but developed class III dyspnea following the new event.
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Media type:  X-RAY

Media file 3:  Fluoroscopy of elevated left hemidiaphragm in a patient with unilateral diaphragmatic paralysis. The diaphragm moves paradoxically upward during inspiration.
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Media type:  X-RAY

Media file 4:  Fluoroscopy of elevated left hemidiaphragm in a patient with unilateral diaphragmatic paralysis. The diaphragm does not move during expiration. For confirmation, a sniff test is required.
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Media type:  X-RAY

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• Multimedia
• References

• Alkofer B, Le Roux Y, Coffin O. Thoracoscopic plication of the diaphragm for postoperative phrenic paralysis: a report of two cases. Surg Endosc. May 2004;18(5):868-70. [Medline].
• Celli BR. Respiratory management of diaphragm paralysis. Semin Respir Crit Care Med. Jun 2002;23(3):275-81. [Medline].
• Chuang ML, Chuang DC, Lin IF. Ventilation and exercise performance after phrenic nerve and multiple intercostal nerve transfers for avulsed brachial plexus injury. Chest. Nov 2005;128(5):3434-9. [Medline].
• Ciccolella DE, Daly BD, Celli BR. Improved diaphragmatic function after surgical plication for unilateral diaphragmatic paralysis. Am Rev Respir Dis. Sep 1992;146(3):797-9. [Medline].
• Easton PA, Fleetham JA, de la Rocha A, Anthonisen NR. Respiratory function after paralysis of the right hemidiaphragm. Am Rev Respir Dis. Jan 1983;127(1):125-8. [Medline].
• Gibson GJ. Diaphragmatic paresis: pathophysiology, clinical features, and investigation. Thorax. Nov 1989;44(11):960-70. [Medline].
• Gierada DS, Slone RM, Fleishman MJ. Imaging evaluation of the diaphragm. Chest Surg Clin N Am. May 1998;8(2):237-80. [Medline].
• Glenn WW. The treatment of respiratory paralysis by diaphragm pacing. Ann Thorac Surg. Aug 1980;30(2):106-9. [Medline].
• Glenn WW, Hogan JF, Loke JS, et al. Ventilatory support by pacing of the conditioned diaphragm in quadriplegia. N Engl J Med. May 3 1984;310(18):1150-5. [Medline].
• Graham DR, Kaplan D, Evans CC, et al. Diaphragmatic plication for unilateral diaphragmatic paralysis: a 10-year experience. Ann Thorac Surg. Feb 1990;49(2):248-51; discussion 252. [Medline].
• Kreitzer SM, Feldman NT, Saunders NA, Ingram RH Jr. Bilateral diaphragmatic paralysis with hypercapnic respiratory failure. A physiologic assessment. Am J Med. Jul 1978;65(1):89-95. [Medline].
• Kumar N, Folger WN, Bolton CF. Dyspnea as the predominant manifestation of bilateral phrenic neuropathy. Mayo Clin Proc. Dec 2004;79(12):1563-5. [Medline].
• Kuniyoshi Y, Yamashiro S, Miyagi K. Diaphragmatic plication in adult patients with diaphragm paralysis after cardiac surgery. Ann Thorac Cardiovasc Surg. Jun 2004;10(3):160-6. [Medline].
• Lisboa C, Pare PD, Pertuze J, et al. Inspiratory muscle function in unilateral diaphragmatic paralysis. Am Rev Respir Dis. Sep 1986;134(3):488-92. [Medline].
• Lloyd T, Tang YM, Benson MD. Diaphragmatic paralysis: the use of M mode ultrasound for diagnosis in adults. Spinal Cord. Dec 6 2005;[Medline].
• Miller JM, Moxham J, Green M. The maximal sniff in the assessment of diaphragm function in man. Clin Sci (Colch). Jul 1985;69(1):91-6. [Medline].
• Piehler JM, Pairolero PC, Gracey DR, Bernatz PE. Unexplained diaphragmatic paralysis: a harbinger of malignant disease?. J Thorac Cardiovasc Surg. Dec 1982;84(6):861-4. [Medline].
• Sandham JD, Shaw DT, Guenter CA. Acute supine respiratory failure due to bilateral diaphragmatic paralysis. Chest. Jul 1977;72(1):96-8. [Medline].
• Ulku R, Onat S, Balci A. Phrenic nerve injury after blunt trauma. Int Surg. Apr-Jun 2005;90(2):93-5. [Medline].
• Xu WD, Gu YD, Lu JB. Pulmonary function after complete unilateral phrenic nerve transection. J Neurosurg. Sep 2005;103(3):464-7. [Medline].

Article Last Updated: May 8, 2006