Skeletal Diseases Influencing Pulmonary Function

Keywords

• pectus excavatum

• Nuss procedure

• Ravitch procedure

Etiology

Pectus excavatum—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 [see Chapter 722 ] or Ehlers-Danlos syndrome [see Chapter 678 ]). It may be acquired secondarily to chronic lung disease, neuromuscular disease, or trauma.

Epidemiology

Pectus excavatum occurs in 1 in 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.

Clinical Manifestations

The deformity is present at or shortly after birth in one-third of cases but is usually not associated with any symptoms at that time. In time, fatigue, chest pain, palpitations, recurrent respiratory infections, wheezing, stridor, and cough may be present. Decreased exercise tolerance is one of the most common symptoms. Because of the cosmetic nature of this deformity, children may experience significant psychologic stress. Physical examination may reveal sternal depression, protracted shoulders, kyphoscoliosis, dorsal lordosis, inferior rib flares, rib cage rigidity, forward head tilt, scapular winging, and loss of vertebral contours ( Fig. 445.1 ). Patients exhibit paroxysmal sternal motion and a shift of point of maximal impulse to the left. Innocent systolic murmurs may be heard.

Laboratory Findings

Lateral chest radiograms demonstrate the sternal depression. 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 have been used historically to help determine the extent of the anatomic abnormality. However, the correlation of the Haller index with the physiologic compromise or associated systems appears suboptimal. Use of 3D chest optical imaging or “surface scan” is gaining popularity in the evaluation. An electrocardiogram may show a right-axis deviation or Wolff-Parkinson-White syndrome (see Chapter 463 ); an echocardiogram may demonstrate mitral valve prolapse (see Chapter 455.3 ) 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 as the result of abnormal chest wall mechanics. Exercise testing may demonstrate either normal tolerance or limitations from underlying cardiopulmonary dysfunction that are associated with the severity of the defect. Pulmonary limitations such as ventilatory limitations and associated flow volume loop abnormalities are commonly seen in younger children and adolescents, whereas additional 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 as defined by physical examination and physiologic assessment of cardiopulmonary function (lung function and exercise tolerance assessment). Therapeutic options include careful observation, use of physical therapy to address musculoskeletal compromise, corrective surgery, cosmetic surgery, and noninvasive thorascopic techniques. For patients with significant physiologic compromise, surgical correction may improve the cosmetic deformity and may help minimize progression or even improve the cardiopulmonary compromise. The 2 main surgical interventions are the Ravitch and Nuss procedures. Superiority of one approach has not been established. The extent of the anatomic defect including the degree of asymmetry may help determine the appropriate surgical approach. While surgical repair may result in improved exercise tolerance for some individuals, usually observed at submaximal exercise intensities, many patients do not show improvement in either respiratory or cardiac function. Normalization of lung perfusion scans and maximal voluntary ventilation have also been observed after surgery. Utilization of a magnetic brace with gradual remodeling (Magnetic Mini Mover procedure) of the pectus deformity is under clinical investigation. The use of surgically placed silicone implants for cosmetic appearance has also been utilized with high patient satisfaction. For selected patients, the use of a more noninvasive approach (i.e., cup suction) has been gaining popularity. Regardless of the treatment approach, addressing the secondary musculoskeletal findings is commonly employed before and after any intervention.

Keywords

• pectus carinatum

• sternal clefts

Pectus Carinatum

Clinical Manifestations

In early childhood, symptoms appear minimal. School-age children and adolescents commonly complain of dyspnea with mild exertion, decreased endurance with exercise, and exercise-induced wheezing. The incidence of increased respiratory infections and use of asthma medication is higher than in nonaffected individuals. On physical examination, a marked increase in the anteroposterior chest diameter is seen, with resultant reduction in chest excursion and expansion ( Fig. 445.2 ). Spirometry has demonstrated both restrictive and obstructive patterns, although the majority of individuals have normal values. Increases in residual volume are often present and result in tachypnea and diaphragmatic respirations. Exercise testing shows variable results. Chest radiographs show an increased anteroposterior diameter of the chest wall, emphysematous-appearing lungs, and a narrow cardiac shadow. The pectus severity score (width of chest divided by distance between sternum and spine; analogous to the Haller index) is reduced.

Treatment

For symptomatic patients with pectus carinatum, minimally invasive surgical correction procedures may result in improvement of the clinical symptoms. Many surgeons prefer to use bracing techniques as a first-line treatment. Although surgery is performed for some individuals who are symptomatic, it is often performed for cosmetic and psychological reasons.