Straight back syndrome is a rare congenital presentation of a perfectly vertical cervicothoracic vertebral spine with absence of normal dorsal curvature. A degree of pectus excavatum is often present, and minimal space is noted between the posterior aspect of the upper manubrium and the vertebral spine (Figure 15-21).45 Dyspnea may occur and restrictive ventilatory defect has been variably described, but some patients have no respiratory complaints. Palpitations and chest pain are other occasional complaints. Mitral valve prolapse is associated. Systolic murmur may be heard. The heart appears enlarged on a roentgenogram but is really displaced to the left by the bony deformities. Pulmonary hypertension during exercise, secondary to elevated pulmonary venous pressure, may be due to compression of the left inferior pulmonary vein against the aorta and the left atrium against the spine.
In a 20-year-old patient with dyspnea, which progressed over several years, the trachea was severely compressed against the vertebral column by the posterior ridge of the upper sternum, and was further indented by the brachiocephalic artery because of a limitation of mediastinal space due to a mild pectus excavatum deformity (Figure 15-22). The distance between the back of the upper sternum and vertebrae measured 1.5 cm. In addition, the lower trachea was splayed out against the vertebral column. Bronchoscopy clearly confirmed these three points of compression. Another patient presented to us with her trachea compressed between the back of the sternum, and a vertical spine, which had followed insertion of a rod for treatment of scoliosis in childhood. The trachea was also significantly indented by the brachiocephalic artery. Whereas this may be an example of an "acquired straight back syndrome," it might be noted that Winter and colleagues called attention to a significant diminution in pulmonary function in patients with idiopathic lordoscoliosis compared to those with kyphoscoliosis.46 Operative correction (Harrington rods and vertebral fusion) usually improved pulmonary function in these patients and also enlarged the space between the sternum and vertebral column. Change in the thoracic inlet, however, was not commented upon.
Our first patient was transferred intubated for acute respiratory distress. Mild pectus excavatum was present. Its correction would not have relieved the tracheal obstruction. The upper point of compression was relieved by excising a plate of the upper sternum, removing the backward folding upper ridge of the manu-brium, and thinning the residual plate of the sternum before replacing it. The brachiocephalic artery was transplanted more proximally and laterally on the ascending aorta to place it parallel to the trachea rather than across the trachea. The third point of narrowing, the distal trachea, was enlarged by fixing the cartilages and membranous wall to a vertical posterior Marlex splint, which returned the cartilages to a normal "C" shape (See Chapter 32,"Surgery for Tracheomalacia, Tracheopathia Osteoplastica, Tracheal Compression, and Staged Reconstruction of the Trachea"). The result was excellent (Figure 15-23). The patient with the apparently acquired problem was treated in similar fashion for upper tracheal compression, since no distal tracheal problem existed. Continued intermittent obstruction, on rolling the clavicular heads forward and inward, necessitated their removal later. Professor Philippe Dartevelle and colleagues (personal communication, 1996) treated a patient with sternal tracheal compression by dividing the sternum and wedging a plate of methyl
figure 15-21 Straight back syndrome. A, Lateral view shows the narrowness of the patient's chest, mild pectus excava-tum, and a spine lacking normal curvatures. B, Posterior view. Absent curvature of the vertebral column is evident. C, Chest roentgenogram. The flattened trachea appears broad and widens even more distally. D, Lateral roentgenogram emphasizes the straight vertebral column. Note the narrowness of the thorax.
figure 15-22 Straight back syndrome in a 20-year-old male with extreme dyspnea, transferred intubated. A, Computed tomography (CT) scan at the thoracic inlet. The trachea is flattened to a slit between the manubrium sterni (and also by the brachiocephalic artery) and the vertebral column. Haller's "pectus index" (ratio of transverse internal diameter of the thorax to anteroposterior distance between sternum and vertebra, measured on CT scan) is 10.8:1 in this patient. Normal is < 3.25. In Haller's 13 to 18-year-old group of patients selected for pectus repair, the maximum indices were about 5:1 (Haller JA Jr, Kramer SS, Lietman SA. Use of CT scans in selection of patients for pectus excavatum surgery: a preliminary report. J Pediatr Surg 1987;22:904-6). B, The distal trachea is splayed against the vertebral column, with a widened membranous wall.
methacrylate between the bony edges. Dr. John C. Wain, at Massachusetts General Hospital, managed a patient with straight back syndrome and pronounced pectus excavatum deformity, by performing a thorough correction of the pectus problem with osteotomies in both the manubrium and gladiolus. The correction was held in place by an Adkins strut. This successfully opened the trachea, which had been compressed to one-third of its normal cross-sectional area. Mori and colleagues corrected an asymptomatic but severe midtracheal stenosis caused by abnormal ossification behind the top of the manubrium, but in a patient with a vertebral column typical of straight back syndrome.47 Andrews and colleagues described a narrowed anteroposterior thoracic dimension due to severe pectus excavatum and kyphoscoliosis, which produced "obstructive sleep apnea" in a 5-year-old, due to compression of the distal trachea and left main bronchus.48 This problem was corrected by pectus repair and aortic suspension. A 15-year-old suffered progressive exercise dyspnea due to tracheal compression by the brachiocephalic artery because of a narrowed thoracic antero-posterior diameter. This was corrected by lateral transplantation of the artery. The curve of the spine was not described in this patient.
Tracheal compromise in similar situations has probably been overlooked in numerous instances. The severity and complexity of the defects vary in the cases cited, which thus far are the only reported instances
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