HISTORY
Day-old boy born at term via vaginal delivery complicated by shoulder dystocia. He had very mild cyanosis in the extremities at birth, which resolved after 5 minutes. Referred for evaluation of respiratory distress. Birth weight, 3.3 kg (7.4 lb). Apgar scores: 7 at 1 minute, and 9 at 5 minutes.
PHYSICAL EXAMINATION
Has tachypnea and weak cry. Diminished breath sounds heard on the left. No murmurs. Chest radiograph is shown.
This patient's anteroposterior chest radiograph shows a paralyzed left hemidiaphragm, suggestive of phrenic nerve injury. Ultrasonography subsequently revealed minimal or paradoxical breathing on the affected side.
The phrenic nerve is composed of the third, fourth, and fifth cervical nerve roots and is a result of migration of the cervical somites as they penetrate the developing diaphragm. Extreme lateral traction caused by shoulder dystocia can stretch the cervical roots of the brachial plexus. Distention or transection of the third to fifth nerve roots can damage the phrenic nerve and lead to paralysis of the diaphragm. Diaphragmatic paralysis occurs in approximately 5% of brachial plexus injuries.1
WHAT’S YOUR DIAGNOSIS?
WHAT'S YOUR DIAGNOSIS?
ANSWER: DIAPHRAGMATIC PARALYSIS SECONDARY TO PHRENIC NERVE INJURY
This patient’s anteroposterior chest radiograph shows a paralyzed left hemidiaphragm, suggestive of phrenic nerve injury. Ultrasonography subsequently revealed minimal or paradoxical breathing on the affected side.
The phrenic nerve is composed of the third, fourth, and fifth cervical nerve roots and is a result of migration of the cervical somites as they penetrate the developing diaphragm. Extreme lateral traction caused by shoulder dystocia can stretch the cervical roots of the brachial plexus. Distention or transection of the third to fifth nerve roots can damage the phrenic nerve and lead to paralysis of the diaphragm. Diaphragmatic paralysis occurs
in approximately 5% of brachial plexus injuries.1
CLINICAL MANIFESTATIONS
When phrenic nerve injury occurs at birth, the paralysis is usually unilateral; the right side is involved in about 80% of patients.1 Typical signs of respiratory distress include cyanosis, apnea, and weak cry. Paradoxical motion of the diaphragm (Kienböck phenomenon) can be seen. GI symptoms, including feeding difficulties and reflux, may be noted, especially with left-sided involvement caused by displacement of the lower esophagus and stomach.2 Most infants have an associated brachial plexus palsy, and the affected limb may assume the characteristic "waiter's tip" position (Erb palsy).
DIAGNOSIS
Phrenic nerve injury is usually determined radiographically. A paralyzed hemidiaphragm is the most common finding. An affected right hemidiaphragm is often at least 2 intercostal spaces higher than the left; an affected left hemidiaphragm is 1 intercostal space higher than the right. Bilateral diaphragmatic paralysis results in symmetric elevation of the diaphragms, which may be evident only to an experienced observer. Other radiographic findings may include atelectasis on the affected side and a stomach bubble elevation with left-sided paralysis.
Diagnosis of diaphragmatic paralysis is confirmed with ultraso- nography.3 The sniff test is a fluoroscopic version of ultrasonography that yields the same information.
MANAGEMENT
Treatment is mainly supportive. Supplemental oxygen can be administered, if necessary. If respiratory distress precludes oral feedings, a nasogastric tube may be inserted. In patients with bilateral injury or severe respiratory distress, continuous positive airway pressure or negative pressure ventilation can be administered.
In patients with persistent respiratory distress or who require prolonged ventilation, a surgical plication is indicated to alleviate symptoms of respiratory distress and prevent recurrent chest infection. This procedure immobilizes and lowers the diaphragm, resulting in increased resting lung volumes and improved action of accessory musculature.
PROGNOSIS
Most newborns with phrenic nerve injury recover in 6 to 12 months with supportive care. In those who have complete avulsion, paralysis is permanent and may lead to eventration (muscle replaced by fibrous tissue) of the diaphragm and persistent difficulty in breathing.
The outcome of plication surgery is usually very good, and mechanical ventilation can generally be discontinued within a week. This has led to more aggressive intervention by surgeons for patients with paralysis and respiratory compromise. However, data on the long-term outcomes for patients who have undergone plication are limited.4
OUTCOME IN THIS CASE
This infant required a diaphragmatic plication to facilitate weaning from mechanical ventilation. The operation was performed on the 16th day of life, and the infant was subsequently weaned from oxygen therapy. At 2-month follow-up, the infant's tachypnea and respiratory distress had completely resolved. A postoperative chest radiograph showed an improved position of the left diaphragm (Figure).
REFERENCES:
1. Volpe JJ. Injuries of extracranial, cranial, and intracranial, spinal cord, and peripheral nervous system structures. In: Volpe JJ, ed. Neurology of the Newborn. 4th ed. Philadelphia: WB Saunders Co; 2001:813-838.2. Whitbourne SK, Griffin IJ. Diaphragmatic paralysis in the newborn. UpToDate 2005. Available at: http://www.uptodateonline.com. Accessed February 18, 2005.
3. Oh KS, Newman B, Bender TM, Bowen A. Radiologic evaluation of the diaphragm. Radiol Clin North Am. 1988;26:355-364.
4. Stone KS, Brown JW, Canal DF, King H. Long-term fate of the diaphragm surgically plicated during infancy and early childhood. Ann Thorac Surg.1987;44:62-65.