Epidemiology

Pectus excavatum occurs in 1 : 400 births with a 9 : 1 male preponderance and accounts for >90% of congenital chest wall anomalies. There is a positive family history in one third of cases.

Etiology

Midline narrowing of the thoracic cavity is usually an isolated skeletal abnormality. The cause is unknown. Pectus excavatum can occur in isolation or it may be associated with a connective tissue disorder (Marfan [Chapter 693] or Ehlers-Danlos syndrome [Chapter 651]). It may be acquired secondarily to chronic lung disease, neuromuscular disease, or trauma.

Clinical Manifestations

The deformity is present at or shortly after birth but is usually not associated with any symptoms at that time. In time, decreased exercise tolerance, fatigue, chest pain, palpitations, recurrent respiratory infections, wheezing, stridor, and cough may be present. Because of the cosmetic nature of this deformity, children may experience significant psychologic stress. Physical examination may reveal sternal depression, protracted shoulders, kyphoscoliosis, inferior rib flares, rib cage rigidity, forward head tilt, scapular winging, and loss of vertebral contours (Fig. 411-1). Patients exhibit paroxysmal sternal motion and a shift of point of maximal impulse to the left. Innocent systolic murmurs may be heard.

Figure 411-1 Pectus excavatum.

Laboratory Findings

Lateral chest radiograms demonstrate the sternal depression. Use of the Haller index on chest CT (maximal internal transverse diameter of the chest divided by the minimal anteroposterior diameter at the same level) in comparison with age- and gender-appropriate normative values for determining the extent of depression of the chest wall anomaly has become useful in determining the extent of the anatomic abnormality. An electrocardiogram may show a right-axis deviation or Wolff-Parkinson-White syndrome (Chapter 429); an echocardiogram may demonstrate mitral valve prolapse (Chapter 422.3) and ventricular compression. Results of static pulmonary function tests may be normal but commonly show an obstructive defect in the lower airways and, less commonly, a restrictive defect due to abnormal chest wall mechanics. Exercise testing may demonstrate either normal tolerance or limitations from underlying cardiopulmonary dysfunction that appear associated with the severity of the defect. Ventilatory limitations are commonly seen in younger children and adolescents, whereas cardiac limitations secondary to stroke volume impairments are more commonly seen in older adolescents and young adults.

Treatment

Treatment is based on the severity of the deformity and the extent of physiologic compromise. Therapeutic options include careful observation, use of physical therapy to address musculoskeletal compromise, and corrective surgery. For patients with significant physiologic compromise, surgical correction may improve the cosmetic deformity and may help minimize or even improve the cardiopulmonary compromise. The 2 main surgical interventions are the Ravitch and Nuss procedures. Although superiority of 1 approach has not been established, there is now >20 years of successful experience with the minimally invasive Nuss procedure. For teenagers with exercise limitations, surgical repair may result in improved exercise tolerance. Normalization of lung perfusion scans and maximal voluntary ventilation have also been observed after surgery. Ongoing treatment to address the secondary musculoskeletal findings is commonly employed before and after the operation.

Pectus Carinatum

Sternal Clefts

Sternal clefts are rare congenital malformations that result from the failure of the fusion of the sternum. Partial sternal clefts are more common and may involve the superior sternum in association with other lesions, such as vascular dysplasias and supraumbilical raphe, or the inferior sternal clefts, which are often associated with other midline defects (pentalogy of Cantrell). Complete sternal clefts with complete failure of sternal fusion are rare. These disorders may also occur in isolation. The paradoxic movement of thoracic organs with respiration may alter pulmonary mechanics. Rarely, respiratory infections and even significant compromise result. Surgery is required early in life, before fixation and immobility occur.

Pathogenesis

A multisystem autosomal recessive disorder, asphyxiating thoracic dystrophy results in a constricted and narrow rib cage. Also known as Jeune syndrome, the disorder is associated with a characteristic skeletal abnormalities as well as variable involvement of other systems, including renal, hepatic, neurologic, pancreatic, and retinal abnormalities. Several genetic loci have been identified in affected individuals.

Clinical Manifestations

Most patients with this disorder die shortly after birth from respiratory failure, although less aggressive forms have been reported in older children. For those who survive the neonatal period, progressive respiratory failure often ensues, owing to impaired lung growth, recurrent pneumonia, and atelectasis originating from the rigid chest wall.

Diagnosis

Physical examination reveals a narrowed thorax that, at birth, is much smaller than the head circumference. The ribs are horizontal, and the child has short extremities. Chest radiographs demonstrate a bell-shaped chest cage with short, horizontal, flaring ribs and high clavicles.

Treatment

No specific treatment exists, although thoracoplasty to enlarge the chest wall and long-term mechanical ventilation have been tried. Rib-expanding procedures have resulted in improved survival.

Prognosis

For some children with asphyxiating thoracic dystrophy, improvement in the bony abnormalities occurs with age. However, children <1 yr old often succumb to respiratory infection and failure. Progressive renal disease often occurs with older children. Use of vaccines for influenza and other respiratory pathogens is warranted, as is aggressive use of antibiotics for respiratory infections.

Clinical Manifestations

Restrictive pulmonary disease, affecting <5% of children with achondroplasia who are younger than 3 yr, is more likely at high elevation. Recurrent infections, cor pulmonale, and dyspnea are commonly associated. There is an increased risk of obstructive sleep apnea, although most patients are not affected. Hypoxemia during sleep is a common feature. Onset of restrictive lung disease can begin at a very young age. On examination, the breathing pattern is rapid and shallow, with associated abdominal breathing. The anteroposterior diameter of the thorax is reduced. Special growth curves for chest circumference of patients with achondroplasia from birth to 7 yr are available. Three distinct phenotypes exist: phenotypic group 1 patients possess relative adenotonsillar hypertrophy, group 2 patients have muscular upper airway obstruction and progressive hydrocephalus, and group 3 patients have upper airway obstruction without hydrocephalus. Kyphoscoliosis may develop during infancy.

Diagnosis

Pulmonary function tests reveal a reduced vital capacity that is more pronounced in males. The lungs are small but functionally normal. Chest radiographs demonstrate the decreased anteroposterior diameter along with anterior cupping of the ribs. The degree of foramen magnum involvement correlates with the extent of respiratory dysfunction.

Treatment

Treatment of sleep apnea, if present, is supportive (Chapter 17). Physiotherapy and bracing may minimize the complications of both kyphosis and severe lordosis. Aggressive treatment of respiratory infections and scoliosis is warranted.

Prognosis

The life span is normal for most children with this condition, except for the phenotypic groups with hydrocephalus or with severe cervical or lumbar spinal compression.

Pathogenesis

Adolescent idiopathic scoliosis (AIS) is characterized by lateral bending of the spine (Chapter 671). It commonly affects children during their teen years as well as during periods of rapid growth. The cause is unknown. Congenital scoliosis is uncommon, affecting girls more than boys, and is apparent in the 1st year of life (Chapter 671.2).

Clinical Manifestations

The pulmonary manifestations of scoliosis may include chest wall restriction, leading to a reduction in total lung capacity. The angle of scoliosis deformity has been correlated with the degree of lung impairment only for patients with thoracic curves. Vital capacity, forced expiratory volume in 1 sec (FEV₁), work capacity, diffusion capacity, chest wall compliance, and PaO₂ decrease as the severity of thoracic curve increases. These findings can be seen in even mild to moderate AIS (Cobb angle <30 degrees) but do not occur in other, nonthoracic curves. Reduction in peripheral muscle function has been associated with AIS through either intrinsic mechanisms or deconditioning. Severe impairment can lead to cor pulmonale or respiratory failure and can occur before age 20 yr. Children with severe scoliosis, especially boys, may have abnormalities of breathing during sleep, and the resultant periods of hypoxemia may contribute to the eventual development of pulmonary hypertension.

Diagnosis

Physical examination and an upright, posteroanterior radiograph with subsequent measurement of the angle of curvature (Cobb technique) remain the gold standard for assessment. Curves >10 degrees define the presence of scoliosis.

Treatment

Depending on the extent of the curve and the degree of skeletal maturation, treatment options include reassurance, observation, bracing, and surgery (spinal fusion). Influenza vaccine should be administered, given the extent of pulmonary compromise that may coexist. Because vital capacity is a strong predictor for the development of respiratory failure in untreated AIS, surgical goals are to diminish the scoliotic curve, maintain the correction, and prevent deterioration in pulmonary function. Abnormalities of vital capacity and total lung capacity, exercise intolerance, and the rate of change of these variables over time should be taken into consideration for the timing of surgical correction. Preoperative assessment of lung function may assist in predicting postsurgical pulmonary difficulties. Many patients undergoing surgical correction may be managed postoperatively without mechanical ventilation. Even patients with mild scoliosis may have pulmonary compromise immediately after spinal fusion, secondary to pain and a body cast that may restrict breathing and interfere with coughing. Children with a preoperative FEV₁ <40% predicted are at risk for requiring prolonged postoperative mechanical ventilation. Rib-expanding procedures have been successful in severe cases of congenital scoliosis.

Clinical Manifestations

Isolated defects of the highest and lowest ribs have minimal clinical pulmonary consequences. Missing midthoracic ribs are associated with the absence of the pectoralis muscle, and lung function can become compromised. Associated kyphoscoliosis and hemivertebrae may accompany this defect. If the rib defect is small, no significant sequelae ensue. When the 2nd to 5th ribs are absent anteriorly, lung herniation and significant abnormal respiration ensue. The lung is soft and nontender and may be easily reducible on examination. Complicating sequelae include severe lung restriction (secondary to scoliosis), cor pulmonale, and congestive heart failure. Symptoms are often minimal but can cause dyspnea. Respiratory distress is rare in infancy.

Diagnosis

Chest radiographs demonstrate the deformation and absence of ribs with secondary scoliosis. Most rib abnormalities are discovered as incidental findings on a chest film.

Treatment

If symptoms are severe enough to cause clinical compromise or significant lung herniation, then homologous rib grafting can be performed. Rib-expanding procedures are also of great value. Adolescent girls with congenital rib anomalies may require cosmetic breast surgery.