The thorax in ankylosing spondylitis.

One of the most interesting and characteristic findings in the condition known in Great Britain as Ankylosing Spondylitis, and in the U.S.A. as Rheumatoid Spondylitis, is the diminution in thoracic, i.e. intercostal, expansion due to involvement of the costo-transverse and costo-vertebral joints. This finding is not seen as a common or characteristic feature in any of the other rheumatic diseases; it is one of the characteristic and pathognomonic physical signs in ankylosing spondylitis. While the vital capacity in any febrile active locomotor disease may be reduced, figures in uncomplicated cases do not descend to the low level seen on occasion in ankylosing spondylitis, nor is the reduction in thoracic expansion as marked. For this reason, although some attention has been devoted to thoracic changes in ankylosing spondylitis (Hamilton, 1949; Hart, 1950), we have paid particular attention to this finding. It is a useful diagnostic pointer; in our series of cases the majority of patients had reduced thoracic expansion on their first attendance at the clinic. This particular finding is prominent and frequent enough to be taken as a cardinal early diagnostic sign. Under treatment by various methods the vital capacity and chest expansion may improve and even return to normal. This has been observed by us by the use of deep x-ray therapy and general body and breathing exercises, and by Swaim (1939) by the use of light jacket supports for the prevention and correction of kyphotic thoracic deformity. Restriction of intercostal respiration is therefore an early sign as well as a late one. It may disappear or lessen in the intermediate phase on therapy, though in many instances vital capacity and chest expansion remain subnormal throughout the course of the disease.