Fig. 501
Congenital malformation of chest. (Sayre.)
Congenital malformations of the thorax are not uncommon, yet but few of them permit of surgical remedy. One or more of the ribs may be absent or defective in formation and produce lateral distortion of the spine. The clavicle also may be defective on one or both sides, or absent. This is a defect which causes but little inconvenience, in spite of its prominence. The chest as a whole may develop defectively or irregularly, some of these conditions being expressions of intra-uterine rickets and others being due to unknown or uncertain causes. Thus we have the absolutely flat chest seen most often in connection with an unduly rounded back, the flattening appearing rather in front, while perhaps the anteroposterior diameter is actually increased. As Hutchinson has shown, this may be a persistence of the fetal type of chest. Pigeon-chest or keel-shaped chest may be regarded as a reversion to a more primitive type, the anteroposterior diameter being increased at the expense of the lateral. The reverse of this deformity is the so-called funnel-shaped chest, where the sternum is depressed and the lateral dimensions increased. In addition to the defects thus noted in the ribs and sternum, absence of a vertebra has been known, the condition not producing deformity, but rather an appreciable shortness of the spine. Malformations are seen frequently in the sternum, which may be fissured in either direction, or may present perforations. With these similar defects of the ribs may also be seen, even to a degree permitting congenital hernia of the thoracic contents.
Supernumerary developments find their expression usually in an added rib, either in the cervical or in the lumbar regions. This condition is practically never noted at birth and may pass unnoticed. Nevertheless a cervical rib may, in adult life, produce discomfort or actual interference with function, partly by pressure upon the subclavian artery or the brachial plexus. When found it is in relation with the seventh cervical vertebra, and the space between it and the first dorsal rib is occupied by muscle developed for the purpose. The scalenus anticus may be inserted into its anterior edge. When sufficiently prominent to produce troublesome symptoms it may be recognized by palpation, and cases of doubt may be made clear by a radiograph. Should it prove troublesome it may be removed, an operation requiring considerable caution, because of its close relation to the pleura, which might easily be opened. It may be exposed by such an incision as would be used for ligation of the subclavian artery.
The thoracic muscles occasionally show anomalies, either in arrangement or by their absence, the pectoralis major being occasionally wanting in whole or in part, and furnishing the most frequent illustration of these defects, which are usually unilateral. (See [Fig. 502].)
Congenital luxations of either extremity of the clavicle are also occasionally seen, particularly of the inner end. A peculiar displacement and relaxation are thereby permitted, with some degree of functional loss.
The acquired malformations of the chest may be produced from a variety of causes. Thus in connection with non-closure of the foramen ovale and the consequent disturbance of heart action, with its overdevelopment of the right auricle, the left side of the chest may be pushed forward and the apex beat found far below its normal position. Asymmetry in the young may also be produced by several different intrathoracic conditions, the most common being pleurisy and empyema, with their consequent distention of the pleural cavity, and later a tendency to cicatricial contraction. In this way marked forms of lateral curvature are produced. In a previous chapter it was stated that overgrowth of lymphoid tissue in the nasopharynx, ordinarily spoken of as adenoids, with consequent embarrassment of respiration, leads in time to stoop shoulders and poor development of the thorax. Deformity may also be produced by such defective vision as shall compel a peculiar or abnormal position of the head.
In chronic emphysema there is noted a peculiar barrel-shape of the chest, which is also to be regarded as an acquired deformity. Paralyses of the internal thoracic muscles will also permit of asymmetrical growth, and projection of the lower angle of the scapula, giving it a wing-like aspect.
Fig. 502