The Importance of Sacro-iliac Changes in the Early Diagnosis of Ankylosing Spondylarthritis

I AMONG the chronic diseases of the spine, ankylosing spondylarthriti2 is one of the most crippling, since its natural result is the complete bony ankylosis of the whole spine. It is a systemic disease which, in its advanced phases, can involve the main joints of the limbs (spondylose rhizomélique of Pierre Marie). The nature of the disease is not yet absolutely determined but it is generally accepted that it starts as an atrophic arthritis of the joints between the facets of the vertebræ (apophyseal joints) which, after an inflammatory stage, become involved by bony ankylosis. Secondarily, there are ossifications of the adjoining ligaments in the ligaments flava, in the anterior and posterior vertebral ligaments, resulting in the classical picture, in the roentgenograms of the bamboo-spine. The clinical picture in the early stages of the disease is very confusing, which is most regrettable since it is proven that the disease is much easier controlled by treatment at this period, before the advent of the ossifications, than later on when the stiffness of the spine is irremediable. The most striking features of the early period are vague and diffused low back pains, sometimes located in the vicinity of the sacro-iliac joints. Not infrequently an acute attack of sciatica is the only clinical incident which marks the onset of the disease. Still more confusing are the cases associated with radiating pains around the chest or the abdomen which are often mistaken for pleurodynia, kidney disease, intestinal disturbances, uterine retroversion, etc. The importance of an early diagnosis of the disease cannot be too greatly emphasized. As long as only inflammatory changes are present in the intervertebral joints and even when some purely fibrous adhesions have taken place, ankylosis of the spine can be avoided by effective treatment which has been established in the past years and which can, in most cases, check the evolution of the disease before ankylosis has taken place. But it must be admitted to-day that such an early diagnosis is missed not only by practitioners but even by qualified specialists. It is our experience that over 80 per cent of the cases of ankylosing spondylarthritis that have come to our observation in the past three years, before the beginning ossifications in the spine, have not been diagnosed as such. Most of them were labelled sciatica muscular rheumatism, lumbago, colitis, pyelitis, etc. A short survey of the principal features of the disease at its early period will establish the basis of the problem. The age of the patients varies between 20 and 35, most of them, after careful questioning, relating the onset of the first mild symptoms to have occurred between the ages of 18 and 25 years. Male patients are observed almost exclusively, the disease among women being a rarity.