Pediatrics

Diaphragm paralysis and eventration

OVERVIEW: What every practitioner needs to know

Are you sure your patient has diaphragmatic eventration or paralysis? What are the typical findings for this disease?

Diaphragm paralysis and eventration are rare but important diagnostic considerations in patients with persistent hypoxemia, especially with hypercarbia, in the neonatal period, after thoracic surgery when it is difficult to wean patients off ventilator support, in patients with high spinal cord injury, and in those with an abnormal diaphragm contour on chest radiography. The clinical picture in both conditions is due to diaphragmatic dysfunction.

Key symptoms and signs of the disease follow:

Dyspnea or respiratory distress usually associated with hypoxemia and/or hypercarbia

Dyspnea tends to worsen when patient is supine compared with an upright position

Exercise intolerance

Weak cough

Recurrent pneumonia and bronchitis

Paradoxical chest and abdominal movements with respiration

Frequent use of accessory muscles of respiration

Decreased air entry with respiratory effort

Recurrent episodes of bronchospasm have been described

Nausea, vomiting, and indigestion can occur in patients with displacement of the gastric fundus into the elevated diaphragm

What other disease/condition shares some of these symptoms?

Atelectasis

Subpulmonic pleural effusion

Congenital diaphragmatic hernia

Neuromuscular disorders (e.g., muscular dystrophy, spinal muscular atrophy, Guillain-Barré syndrome).

Skeletal muscle relaxant medications (e.g., after anesthesia)

Subdiaphragmatic fluid collections (e.g., subdiaphragmatic abscess or ascites)

Cystic adenomatoid malformation or pulmonary sequestrations

Pulmonary hypoplasia

Severe thoracic deformation (e.g., kyphoscoliosis)

What caused this disease to develop at this time?

Any of the following clinical settings might be associated with diaphragmatic paralysis:

A difficult vaginal delivery with or without obvious traumatic birth injury

High spinal cord injury, involving the cervical third through fifth nerve roots

History of cardiothoracic surgery causing phrenic nerve injury

A respiratory illness (e.g., infection or atelectasis) can unmask an otherwise subclinical diaphragmatic paralysis or eventration.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

A blood gas determination to confirm hypoxemia and hypercarbia can be helpful. However, the patient may compensate quite well if there is unilateral diaphragmatic paralysis or eventration, with resultant normal blood gas levels. An elevated base excess and bicarbonate level in the blood gas suggest chronic hypoventilation when paralysis or eventration has been long standing.

Pulmonary function testing can provide supportive diagnostic assistance and help identify functional respiratory deficits from diaphragm dysfunction. The forced vital capacity (FVC) is often decreased, suggesting a restrictive ventilatory defect. A 15%-25% drop in FVC when spirometry is performed with the patient supine as compared with upright, supports diaphragmatic dysfunction but is not diagnostic. Assessment of maximum voluntary ventilation, sniff pressure, and maximum inspiratory pressure can provide functional assessment of ventilatory impairment to assist with management decisions. Peak cough flow assessment can help identify impairment in efficacy of the cough.

Overnight oximetry can detect nocturnal hypoxemia or suggest rapid eye movement (REM) sleep–associated sleep disordered breathing. Polysomnography can confirm the presence and severity of sleep apnea as well as nocturnal hypoventilation in patients with adequate daytime ventilation. Even in the absence of sleep apnea, REM sleep– associated hypoventilation can occur in patients with diaphragmatic dysfunction.

Would imaging studies be helpful? If so, which ones?

Chest radiography is often the initial radiographic evaluation that raises suspicion of the diagnosis, especially when there is asymmetry between the heights of the hemidiaphragms.

Ultrasonography of the chest not only can identify abnormal diaphragm motion and thickness, enabling diagnostic confirmation but also can help exclude some differential diagnoses (e.g., pleural effusions, subdiaphragmatic fluid collections, congenital diaphragmatic hernia, sequestrations, and cystic adenomatoid malformations). Neuromuscular ultrasound is an evolving technique used to image the diaphragm with targeted high-resolution images.

The advantage of this modality is lack of radiation exposure and relatively low cost without much patient discomfort. Ultrasonographic diagnosis, however, does require radiologist expertise and experience for reliable results. Utility is limited for patients on ventilator support. Further, ultrasonography provides qualitative assessment of diaphragm function but cannot quantify diaphragm function (i.e., determine functional impairment).

A computed tomographic scan of the chest can help differentiate a pleuropulmonary or intraabdominal pathologic condition mimicking diaphragmatic paralysis or eventration.

Fluoroscopy carries higher radiation exposure but can identify abnormal diaphragm motility and can be of diagnostic assistance. Fluoroscopy assesses excursion of individual domes and shift of the mediastinum via the sniff test of Hitzenburger.

Electromyography and nerve conduction studies of the diaphragm and phrenic nerve can provide diagnostic support but may have limited availability and require the expertise of a neurologist. The test is also associated with patient discomfort.

Newer techniques include dynamic magnetic resonance imaging, which entails quantitative assessment of excursion and synchronicity and velocity of diaphragm motion. Disadvantages of this modality includes operator dependence, limited availability, high costs, and the need for patient transport.

If you are able to confirm that the patient has diaphragmatic dysfunction, what treatment should be initiated?

Hypoxemia should be corrected with oxygen supplementation under close monitoring in patients with hypercarbia to ensure that hypoventilation does not worsen with blunting of the hypoxic ventilatory drive. Patients with severe respiratory distress may require intubation and mechanical ventilator support. Patients with primarily nocturnal hypoventilation may benefit from noninvasive ventilatory support (e.g., bilevel positive airway pressure support).

Nutritional support with nasogastric tube feedings may be required. Caloric fortification can result in development of hypercarbia from increased metabolism in the face of hypoventilation.

Patients unable to wean from mechanical ventilation or those requiring considerable daily noninvasive respiratory support (e.g., more than 16 hr/day) may require placement of a tracheostomy for chronic mechanical ventilatory assistance. Patients with significant respiratory compromise such as those with considerable exercise intolerance, recurrent lower respiratory infections, failure to thrive, recurrent atelectasis, pulmonary hypertension, or heart failure may benefit from surgical plication of the diaphragm. Plication immobilizes and lowers the diaphragm, thereby improving functional residual capacity and efficiency of the intercostal as well as abdominal muscles.

Patients with expectation of relatively rapid diaphragmatic recovery (e.g., pharmacologic neuromuscular blockade, Guillain-Barré syndrome) may be supported with ventilatory assistance in the interim.

Pulmonary rehabilitation/physical therapy was thought to be beneficial in a pediatric case series of patients with diaphragmatic paralysis.

What are the adverse effects associated with each treatment option?

Tracheostomy and ventilator placement may be associated with a significant burden of care, especially when patients are discharged home on such interventions. Complications of tracheostomy may include airway granulations, suprastomal collapse, translaryngeal air leak rendering the ventilator less effective, and feeding, speech, and vocalization difficulties. Accidental decannulations of the tracheostomy may be fatal in patients with severe respiratory compromise.

Noninvasive ventilation may lose efficacy if the mask does not fit properly and/or if there are airflow leaks, development of pressure ulcerations on the face from the mask interface, or significant thoracic deformity (e.g., scoliosis). Craniofacial deformation from long-term use of noninvasive ventilation in children is also known.

Diaphragmatic pacing can induce phrenic nerve impairment over the long term. A tracheostomy may still be required because of laryngeal and upper airway muscle asynchrony during stimulated diaphragmatic contraction. (Normally during inspiration, the brainstem respiratory control centers effect increased pharyngeal dilator muscle tone and vocal cord abduction with diaphragm contraction, which will fail to occur when paced diaphragmatic contraction occurs.)

What are the possible outcomes of diaphragm dysfunction?

The prognosis depends on the underlying cause and its reversibility. A pediatric study of 11 patients with isolated diaphragmatic paralysis reported 7 patients achieving partial weaning from respiratory support at an average of 2.6 months (range 3 weeks-6 months) and complete weaning from respiratory support at 5.4 months (range 1.5-12 months) after diagnosis. These children reportedly recovered without sequelae. A prospective study of 59 children with phrenic nerve palsy after cardiac surgery noted that the palsy was mostly transient in nature. Another retrospective study of 47 patients with diaphragmatic paralysis after cardiac surgery reported that plication was helpful in weaning most of those patients from ventilator support. Predicting recovery is difficult and needs careful clinical judgment.

Nonintervention or inadequate intervention may result in recurrent atelectasis causing respiratory distress, impaired airway clearance with secondary recurrent bronchitis or pneumonia, and cor pulmonale from the chronic hypoventilation. Permanent loss of lung function from chronic atelectasis and/or recurrent pulmonary infections can occur. Exercise intolerance may have functional consequences in the child's activities of daily living or social interactions.

What causes this disease and how frequent is it?

What causes diaphragm eventration and how frequent is it?

Diaphragmatic eventration can be congenital or acquired and is due to hypoplasia of the diaphragm. More boys than girls are affected. Although the exact incidence or prevalence is unknown, one literature report described a prevalence of 1/1400 chest radiographs. Congenital eventration occurs because of inadequate development of the diaphragmatic muscle or phrenic nerves. There can be partial or complete involvement of the diaphragm muscle. In the latter, the diaphragm is replaced by a thin membranous structure. Acquired eventration can occur secondary to disuse muscular atrophy after phrenic nerve injury (e.g., traumatic birth injury or thoracic surgery).

What causes diaphragmatic paralysis and how frequent is it?

Diaphragmatic paralysis may result from diaphragmatic muscle or phrenic nerve dysfunction. Etiologic considerations for this include the following:

Cardiac surgery, following which an incidence of 0.5%-1.5% has been reported

Traumatic birth injury, particularly involving the head and neck

Spinal cord injury, particularly when involving the cervical third to fifth nerve roots

Cervicobrachial surgery

Complications with central venous catheter placement, at which time the phrenic nerve can be injured

Involvement by mediastinal tumors and as a sequela of their resection (e.g., neuroblastoma)

Mediastinal or pulmonary infections when they involve the phrenic nerve (e.g., tuberculous lymphadenopathy)

Infectious or inflammatory polyneuropathies

Brainstem disorders

Physical manipulation of the diaphragm during abdominal surgery; may result in temporary reflex paresis of the muscle (typically lasting minutes to hours)

Transient phrenic nerve paralysis has been described with status asthmaticus in a 9-year-old boy.

Hereditary neuromuscular disorders may also manifest with diaphragm weakness/paralysis and phrenic nerve dysfunction

How do these pathogens/genes/exposures cause the disease?

The phrenic nerve has a long course from the neck to the diaphragm. It becomes superficial in the neck where it rests on the ventral surface of scalenus anterior covered by the sternomastoid muscle. It then crosses the apical pleura, coursing in front of the lung root and lateral to the pericardium before reaching the diaphragm. This lengthy path predisposes the nerve to injury during cervical, cardiac, and thoracic surgery.

Other clinical manifestations that might help with diagnosis and management

Diaphragmatic paralysis should be suspected in infants with respiratory distress and Erb palsy secondary to birth injury. Clavicular fractures and vaginal delivery of an infant with breech presentation are also risk factors for diaphragmatic paralysis. Consider the diagnosis when such infants are noted to have respiratory distress, recurrent atelectasis, or an elevated diaphragm on chest radiography.

What complications might you expect from the disease or treatment of the disease?

Impaired cough may result in retention of lower airway secretions. This can predispose to chronic atelectasis and recurrent bronchopulmonary infections, both of which can lead to pulmonary scarring and secondary loss of lung function.

Hypoventilation can result in hypoxemia, hypercarbia, and respiratory distress with secondary failure to thrive, sleep-disordered breathing, cognitive impairment, cor pulmonale, and even death.

Exercise intolerance and thoracic deformity can occur because of diaphragmatic dysfunction. This may have functional and psychosocial implications for the child and family.

Pulmonary hypoplasia can potentially occur when the conditions are present from fetal life or early infancy.

There are case reports of spontaneous rupture of diaphragmatic eventration causing life-threatening respiratory distress.

Are additional laboratory studies available; even some that are not widely available?

Magnetic phrenic nerve stimulation has been used successfully to determine diaphragmatic paralysis in an infant with minimal patient discomfort. Availability may be limited to specialized centers.

Measurement of transdiaphragmatic pressure changes with a simultaneously placed esophageal (measuring pleural) and gastric (measuring abdominal pressure change) balloon is the gold standard but has limited clinical availability. However, this is an invasive and expensive procedure and does not enable diagnosis of unilateral weakness.

How can diaphragmatic eventration and paralysis be prevented?

High-risk vaginal deliveries, particularly those with cephalopelvic disproportion and breech presentation, should be avoided.

Even with the best surgical techniques, diaphragmatic paralysis can occur during cervical, thoracic, and cardiac surgery.

Prophylactic immunizations, including annual influenza vaccine and expanded pneumococcal vaccine (when age appropriate) can be considered in these patients to reduce the risk of respiratory morbidity. Palivizumab prophylaxis for respiratory syncitial virus may be considered in young infants with diaphragmatic eventration or paralysis, particularly when there is significant ventilatory compromise.

Optimization of nutrition and physical therapy may reduce functional impairment secondary to diaphragm dysfunction.

Genetic counseling in patients with neuromuscular disorders may help avoid future family members being affected with the condition.

What is the evidence?

Smith, CD, Sade, RM, Crawford, FA. "Diaphragmatic paralysis and eventration in infants". J Thorac Cardiovasc Surg. vol. 91. 1986. pp. 490-7.

Commare, MC, Kurstjens, SP, Barois, A. "Diaphragmatic paralysis in children: a review of 11 cases". Pediatr Pulmonol. vol. 18. 1994. pp. 187-93.

Sarwal, A, Walker, FO, Cartwright, MS. "Neuromuscular ultrasound for evaluation of the diaphragm". Muscle Nerve. vol. 47. 2013. pp. 319-29.

(Important review of diagnosis, outcomes, and literature.)

Fitting, JW, Grassino, A. "Diagnosis or diaphragmatic dysfunction". Clin Chest Med. vol. 8. 1987. pp. 91-103.

Rafferty, GE, Greenough, A, Dimitriou, G. "Assessment of neonatal diaphragmatic paralysis using magnetic phrenic nerve stimulation". Pediatr Pulmonol. vol. 27. 1999. pp. 224-6.

Boussages, A, Gole, A, Blanc, P. "Diaphragmatic motion studied by M-mode ultrasonography: methods, reproducibility and normal values". Chest. vol. 135. 2009. pp. 391-400.

(Adult data.)

Watanabe, T, Trusler, GA, Williams, WG. "Phrenic nerve paralysis after pediatric cardiac surgery. Retrospective study of 125 cases". J Thorac Cardiovasc Surg. vol. 94. 1987. pp. 383-8.

Sivan, Y, Galvis, A. "Early diaphragmatic paralysis in infants with genetic disorders". Clin Pediatr. vol. 2. 1990. pp. 169-71.

Baughn, JM, Gershan, WM, Jacobson, RD. "Diaphragmatic paralysis and stridor in an infant". Am J Respir Crit Care Med. vol. 181. 2010. pp. A6205.

Goffart, Y, Moreau, P, Biquet, JF. "Phrenic nerve paralysis complicating craniofacial surgery". Acta Otorhinolaryngol Belg. vol. 42. 1988. pp. 564-70.

Pleasure, JR, Shashikumar, VL. "Phrenic nerve damage in the tiny infant during vein cannulation for parenteral nutrition". Am J Perinatol. vol. 7. 1990. pp. 136-8.

Goussard, P, Gie, RP, Kling, S. "Phernic nerve palsy in children associated with confirmed intrathoracic tuberculosis: diagnosis and clinical course". Pediatr Pulmonol. vol. 44. 2009. pp. 345-50.

Saha, S, Bal, HS, Sen, S. "Spontaneous rupture of a congenital diaphragmatic eventration in an infant". BMJ Case Rep. May 14;2015.

Gun, F, Gunendi, T, Erginel, B, Guler, N, Celik, A. "Rupture of a congenital diaphragmatic eventration in a child: report of a case". Surg Today. vol. 41. 2011. pp. 1630-2.

Santuz, P, Piccoli, A, Zaglia, F. "Transient phrenic nerve paralysis associated with status asthmaticus". Pediatr Pulmonol. vol. 38. 2004. pp. 269-71.

Hamilton, JR, Tocewicz, K, Elliot, MJ. "Paralysed diaphragm after cardiac surgery in children: value of plication". Eur J Cardiothorac Surg. vol. 4. 1990. pp. 487-590.

Affatato, M, Villagra, F, deLeon, JP. "Phrenic nerve paralysis following pediatric cardiac surgery. Role of diaphragmatic plication". J Cardivasc Surg. vol. 29. 1988. pp. 606-9.

Haller, JA, Pickard, LR, Tepas, JJ. "Management of diaphragmatic paralysis in infants with special emphasis on selection of patients for operative plication". J Pediatr Surg. vol. 14. 1979. pp. 779-85.

Shiohama, T, Fujii, K, Hayashi, M, Hishiki, T, Suyama, M, Mizuochi, H. "Phrenic nerve palsy associated with birth trauma--case reports and a literature review". Brain Dev. vol. 35. 2013. pp. 363-6.

Godfrey, M, Hilditch, AR, Kikiros, C, Rao, S. "Birth injury-related diaphragmatic paralysis manifesting as protracted vomiting and CPAP dependency". J Paediatr Child Health. vol. 48. 2012. pp. 80-1.

Yilmaz, Y, Ulu, H. "Phrenic nerve injury due to thoracentesis for TPN effusion in a preterm newborn: consecutive two unusual complications". Tuberk Toraks. vol. 59. 2011. pp. 384-7.

Magnetic resonance imaging modality

Chavhan, GB, Babyn, PS, Cohen, RA, Langer, JC. "Multimodality imaging of the pediatric diaphragm: Anatomy and pathologic conditions". Radiographics. vol. 30. 2010 Nov. pp. 1797-1817.

Gierada, DS, Curtin, JJ, Erickson, SJ, Prost, RW, Strandt, JA, Goodman, LR. "Diaphragmatic motion: Fast gradient-recalled-echo MR imaging in healthy subjects". Radiology. vol. 194. 1995 Mar. pp. 879-884.

Prognosis of diaphragmatic paralysis after cardiac surgery

Zhang, YB, Wang, X, Li, SJ, Yang, KM, Sheng, XD, Yan, J. "Postoperative diaphragmatic paralysis after cardiac surgery in children: incidence, diagnosis and surgical management". Chinese medical journal. vol. 126. 2013. pp. 4083-7.

Aguirre, VJ, Sinha, P, Zimmet, A, Lee, GA, Kwa, L, Rosenfeldt, F. "Phrenic nerve injury during cardiac surgery: mechanisms, management and prevention". Heart, lung & circulation. vol. 22. 2013. pp. 895-902.

Smith, BM, Ezeokoli, NJ, Kipps, AK, Azakie, A, Meadows, JJ. "Course, predictors of diaphragm recovery after phrenic nerve injury during pediatric cardiac surgery". The Annals of thoracic surgery. vol. 96. 2013. pp. 938-42.

El Tantawy, AE, Imam, S, Shawky, H, Salah, T. "Diaphragmatic nerve palsy after cardiac surgery in children in Egypt: outcome and debate in management". World journal for pediatric & congenital heart surgery. vol. 4. 2013. pp. 19-23.

Most evidence for management of diaphragmatic paralysis and eventration in children is grade C or D. Consultation with appropriate specialists is recommended when managing these patients.

Ongoing controversies regarding etiology, diagnosis, treatment

The optimal timing of surgical plication is not certain. The advantage of early intervention is improved pulmonary dynamics with lower risk of loss of lung function and complications. As surgical plication is often not reversible, an argument for delayed surgery can be made to provide opportunity for spontaneous diaphragmatic recovery. Respiratory improvement with continuous positive airway pressure therapy, which increases functional residual capacity and splints the diaphragm, may help identify patients who can benefit from plication.

Diaphragmatic pacing may be an option for those patients in whom there may be sufficient residual phrenic nerve or diaphragmatic function. Repeated artificial phrenic nerve stimulation itself may lead to degenerative changes in the nerve.

It may not be possible to differentiate diaphragmatic eventration from paralysis clinically or with commonly used clinical investigations.

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