eMedicine Specialties > Pulmonology > Diaphragmatic Disorders

Diaphragmatic Paralysis

Author: Sat Sharma, MD, FRCPC, Professor and Head, Division of Pulmonary Medicine, Department of Internal Medicine, University of Manitoba; Site Director, Respiratory Medicine, St. Boniface General Hospital
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Updated: May 8, 2006

Introduction

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

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

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