Ankylosing spondylitis.
Ankylosing spondylitis is an inflammatory disease involving entheses and joints, especially those in and around the spine. The most widespread involvement of the respiratory system by this disease occurs when this pathological process gives rise to chest wall pain, diminished chest wall movement and a dorsal stoop. As healing of the inflammatory process takes place, calcification occurs which leads to rigidity of these structures, with consequent loss of chest expansion which is exacerbated by the increasingly kyphotic spinal posture and intercostal muscle inefficiency. Fortunately diaphragmatic function is unimpaired and compensates well, so that there are only minor restrictive changes found in tests of respiratory function. Treatment is by mobilizing physiotherapy coupled with a home exercise programme encouraging mobility and improved cardiovascular fitness. As with many physical treatment methods, good quality controlled studies of efficacy are rare. The role of medication is to ease symptoms and hence enable exercise. Apical fibrobullous lung disease is found in a small proportion of AS patients. The initial changes are mainly fibrotic, with bullae becoming more important as the condition progresses. The disease may progress to major cavitation, which is prone to infection, especially with aspergillae. No methods exist which can either prevent the development of fibrobullous disease or halt its progression, although this may happen spontaneously. The main effects of therapy are aimed at the diagnosis and treatment of superinfection. Treatment of established aspergillosis, especially when aspergilloma formation has taken place, is unsatisfactory and carries substantial risks of morbidity and death. Non-apical pleural involvement, including pleural effusion, is very rare. The most common cause of breathlessness in AS patients is cardiac involvement by the disease.