Chest Wall

Most of the pathological conditions here are due to diseases of the thoracic cage. With deformities of the thorax such as kyphoscoliosis, the scoliotic spine may give the impression of a large mediastinal mass (Fig. 23), until a penetrated film shows the striped translucencies that represent the intervertebral discs. At the same time, the intercostal spaces are narrowed and ribs vertically oriented on the concave side, with widening intercostal space and diverging ribs on the convex side. Similar changes can be seen in healed pulmonary tuberculosis with massive shrinking and volume reduction of the hemithorax on the affected side with growth retardation. Thoracoplasty performed to eradicate tuberculous cavities in the apex of the lung may produce thoracic deformity due to resection of four to six upper ribs.

A funnel-shaped sternum may be projected deep into the thorax in the lateral view (Fig. 24), and the heart may be displaced to the left. A bowed, forward bulging sternum may be seen with congenital heart diseases and pulmonary emphysema. Aneurysms in the ascending aorta may cause notching of the sternum.

Fractures are the most common cause of changes in the ribs. A very recent fracture is often difficult to recognize unless the fragments are dislocated. It is usually unnecessary to verify clinically suspected fracture

Figure 24. Lateral view of patient with funnel chest (pectus excavatum). The sternum is projected over the heart shadow.

of the ribs by radiography. If an accompanying pneumothorax is suspected, a radiograph is necessary. Rib fractures become readily visible on healing, with callus formation; old healed rib fractures may be misinterpreted as lung opacities by the inexperienced observer. Rib destruction may be recognized as indicative of metastases to the thoracic cage or direct invasion of the chest wall by intrathoracic neoplasms. The bone structure may have vanished along part of the course of the rib. Destruction of ribs can easily be overlooked unless each rib is systematically evaluated from the back to front, comparing the two sides.

Rib notching consists of small depressions of the lower edges of the ribs. They are usually caused by pressure from dilated pulsating intercostal arteries in coarctation of the aorta. The narrowed section of the aorta is located below the origin of the left subclavian artery. In order to preserve the blood supply to the descending aorta, collateral circulation develops through branches of the subclavian arteries, the internal mammary arteries with blood flowing retrograde through the intercostal arteries to the descending aorta. Multiple neurinomas in the intercostals nerves (neurofibromatosis) can also cause rib notching. Patients with pain in the front of the chest wall, costochondral osteochondritis (Tietze syndrome), usually have no radiological changes.

After dissection of lymph nodes or other extensive surgery in the neck, caudal displacement of the lateral clavicle and so-called "hanging shoulder" may be observed. This is due to a paresis of the trapezius muscle because of damage to the 11th cranial nerve (accessory nerve).

Alf Kolbenstvedt, Arnulf Skjennald and Charles B. Higgins