Spondylothoracic dysplasia (SD) is an inherited condition that results in dwarfism (short trunk), a prominent back of the skull, broad forehead, and wide nasal bridge, also results in severe respiratory problems from thoracic insufficiency syndrome. The skeletal deformities (ribs and spine) compress the area where the lungs should expand, making it difficult to breathe.
The authors of this study looked into the respiratory status of patients with SD, using x-rays and imaging tests, as well as pulmonary function tests. To do the study, the researchers identified 28 patients who fit the requirements for the study. Nine had been identified at birth while they were in the neonatal intensive care units; 8 died during the neonatal period due to respiratory complications. They were not included in the results because the patients died before computed tomography imaging (CT scan) could be done. The remaining patients, aged from 4 months to 9 years, completed the study. The researchers included 9 other patients who were older, ranging in age from 12 to 49 years.
The patients were seen in hospital emergency rooms, on average, 4.2 times during their first year of life. The visits were due to respiratory problems. This average number of visits dropped to 2 per year after the first year.
Evaluation of the patients showed that they had normal vital signs for their age (blood pressure, temperature, pulse), as well as appropriate respiratory rate, with clear lungs. Their abdomens protruded and rib cages were lower than normal. On average, the patients were in the 1.15 percentile range. Seventy percent of the patients were underweight for their height.
X-rays of the patients’ torso showed that the rib cage was asymmetrical and shortened to about 24.2 percent of predicted normal length. Five of the 20 patients had scoliosis (curvature of the spine). Computed tomography scans showed that the lung volume was 28 percent lower than normal. As well, the amount of air capacity, the forced vital capacity or FEV1, was 27.9 percent of the predicted normal value. The diaphragm was affected among the study patients, as was the trachea in 9 of the 20 patients.
The researchers discovered that the patients with SD who survived infancy were able to live relatively well with no progression of the abnormalities. Their body appeared to adapt to the lower respiratory function, although there is no clinical evidence as to how this happens.