Diseases of the diaphragm
Associate-Editor-in-Chief: Cafer Zorkun, M.D., Ph.D. 

# Normal Anatomy of Diaphragm
- Composed of a central tendinous portion and a peripheral muscular portion
- Muscular portion consists of sternal, costal, and lumbar components
- Three major openings: aortic (aorta, azygos vein, thoracic duct), esophageal (esophagus, vagus nerves), caval (IVC)
- Right and left phrenic arteries arise from the abdominal aorta
- Additional arterial supply from pericardiophrenic and musculophrenic arteries
- Venous drainage is via right and left phrenic veins to the IVC; some drainage to the left renal vein as well
- Right and left phrenic nerves supply both sensory and motor innervation

# Eventration of the Diaphragm
It is also called elevated hemidiaphragm or raised hemidiaphragm. Chest x-rays are usually enough for diagnosis and CT of the chest and upper abdomen is useful for confirmation.

## Elevation of the right hemidiaphragm
(Images shown below are courtesy of Cafer Zorkun MD PhD and copylefted)
- File:RDE 001.jpg
- File:RDE 002.jpg
- File:RDE 003.jpg
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## Elevation of the left hemidiaphragm
(Images shown below are courtesy of Cafer Zorkun MD PhD and copylefted)

## Elevation of both hemidiaphragms
(Image shown below is courtesy of Cafer Zorkun MD PhD and copylefted)
- File:BDE 001.jpg

# Congenital Diaphragmatic Hernias

## Bochdalek's Hernia
- Occurs posterolateral in the area of the 10th and 11th ribs
- 90% occur on the left
- 2:1 male to female incidence
- Usually isolated and not associated with other congenital defects
- Typically manifests as acute respiratory distress
- CXR demonstrates intestine in the thorax and shift of mediastinal contents to the right
- Initial treatment includes NG decompression, positive-pressure ventilatory support, and surgical correction
- Approach left-sided defect through the abdomen in order to explore for malrotation and obstruction
- Right-sided defects are repaired through a thoracotomy
- Postoperative mortality can be as high as 50%, mostly attributed to increased pulmonary vascular resistance
- ECMO is useful to reduce pulmonary vascular resistance and help resolve persistant fetal circulation

## Morgagni's Hernia
- Defect occurs in a subcostosternal location
- Uncommon (less than 3% of diaphragmatic hernias) and usually asymptomatic
- Well defined hernia sac becomes symptomatic typically after age 40, when obesity, pregnancy, or trauma increases intraabdominal pressure
- The transverse colon is the most common organ to herniate, and can present as an acute colonic obstruction
- Repair is usually performed through a upper midline incision

## Esophageal Hiatal Hernia
- Congenital defects causing these hernias are uncommon in adults, but some neonates and infants may have reflux associated with an esophageal hiatal hernia
- Typical symptoms are vomiting, respiratory complications, anemia, and failure to thrive
- Diagnosis rests on esophagography, fluoroscopy, and pH monitoring
- Treatment is primarily medical; surgery is indicated for medical failure

# Tumors of the Diaphragm

## Primary
- Rare tumors; cysts are more common than inflammatory masses, which are more common than neoplasms
- Equal male:female incidence; left-sided tumors are slightly more common than right-sided tumors
- Symptoms include pain, cough, dyspnea, and GI symptoms
- CXR and CT scan will localize the tumor
- The majority of neoplasms are benign (60%), which are usually cysts
- Up to 40% are malignant, usually sarcomas
- Treatment includes excision and closure of the diaphragmatic defect

## Metastatic
- Most neoplastic involvement of the diaphragm occurs from contiguous extension of nearby tumors
- The most common lesions arise from lung, esophagus, stomach, liver, and the retroperitoneum
- Treatment is based on the primary tumor

# Traumatic Perforation
- Penetrating perforation should be suspected with any thoracic injury below the level of the nipples (5th ICS)
- Most blunt hernias are caused by automobile accidents, and about 90% occur in the left hemidiaphragm
- Blunt trauma defects are large, usually about 10-15 cm, and typically located in the posterior left hemidiaphragm
- Stomach is the most commonly herniated organ, followed by spleen, colon, small bowel, and liver
- Respiratory insufficiency is common early, while intestinal obstruction predominates later
- CXR and CT scan will diagnose most; barium contrast is contraindicated, as it can produce a total obstruction in this setting
- Missed injury and delayed diagnosis commonly leads to bowel incarceration and obstruction
- Mortality is relatively high (15-40%) due to high incidence of associated injuries
- Repair should be undertaken promptly with full exploration for other injuries
- Left-sided perforation should be repaired through the abdomen to allow correction of associated injuries
- Right-sided perforations may require thoracotomy

# Pacing

## Indications
- Sarnoff (1940's) and Glenn (1950's) were the primary developers of diaphragmatic pacers
- Pacing is indicated in patients who have chronic ventilatory insufficiency with normal nerves, lungs and diaphragm
- This includes some quadriplegic patients and central alveolar hypoventilation
- Contraindications to pacing are lower motor neuron dysfunction, muscular dystrophy, and extensive lung disease

## Mechanism
- There are four components to a diaphragmatic pacer:
- Transmitter: sets respiratory rate and length of inspiration
- Antennae: transfers signal across intact skin to the receiver
- Receiver: obtains signal and energy from external portion by inductive coupling
- Electrode: stimulates the phrenic nerve
- The electrode portion is usually implanted on the phrenic nerve through the 2nd ICS anteriorly
- The receiver is placed in a subcutaneous pocket

## Central Alveolar Hypoventilation
- Features of CAH include: hypoxemia and hypercapnia increasing with sleep, hypoventilation or apnea during sleep, and clinical findings of cyanosis, polycythemia, and cor pulmonale
- These patients have near-normal ventilatory capacity tests, but have a reduced response to induced hypoxemia and hypercapnia
- Absence of upper airway obstruction or persistence after relief must also be demonstrated
- These patients should begin pacing within 3 weeks of operation

## Quadriplegia
- Patients with high cervical lesions (C1 or C2) are suitable candidates; injury to C3-C5 may injure the motor component of the phrenic nerves, preventing adequate pacing
- Delay surgery for several months to allow for potential recovery after spinal cord injury
- Pacing should be gradually introduced to avoid diaphragmatic fatigue and permanent damage
- Patients should be selected who are good candidates for long-term rehabilitation