Pulmonary involvement in ankylosing spondylitis

Respiratory problems in patients with ankylosing spondylitis may be due to the reduction of chest wall expansion and to intrinsic lung involvement. The inability to expand the chest due to the fusion of the thoracic joints does not usually result in ventilatory insufficiency by reason of increased diaphragmatic function. Vital capacity and total lung capacity are not markedly reduced and are correlated with reduction of chest expansion intrinsic lung disease consists in a fibro-bullous apical disease, described for the first time in the 1940s and now well recognized, and interstitial lung disease recently found in studies using high-resolution CT.