Ankylosing Spondylitis (AS) is a chronic inflammatory disease of unknown etiology characterized by prominent inflammation of spinal joints and adjacent structures. This inflammation leads to progressive fusion of the spine. Peripheral joints are less affected although the hips and shoulders may become involved in one third of cases. Also, inflammation of extraarticular organs, such as the eye and heart, may occur.
Males appear to be affected more than females. Age of onset ranges from adolescence to age 25 and peaks around 28 years. Approximately 15% of adult American and European cases have been found to have a childhood onset.
Disease susceptibility is strongly linked genetically. HLA-B27 is the gene associated with most cases. A positive family history of AS can be found in 15% to 20% of cases.
In the majority of cases, AS produces progressive stiffness and spinal restriction with intermittent exacerbations. Chronic low back pain and stiffness are typically the first symptoms. Onset is usually slow rather than abrupt and patients often cannot date when symptoms first began, or precisely localize the areas affected.
Characteristically, inflammatory back symptoms are suggested by prominent stiffness and pain in the morning or following other periods of rest (gel phenomenon) that improve with exercise. Back pain often forces the individual out of bed at night and is unrelieved by lying down. The earliest abnormality is usually tenderness in the sacroiliac joints. Most individuals are able to remain at work.
The characteristic radiographic change in AS is the “bamboo spine”.
The major aims of management include pharmacologic relief of pain and stiffness and a physical therapy and lifestyle modification program aimed at preserving spinal mobility or at least preventing spinal deformity and disability. Also, it is imperative that prompt recognition and management of articular and extraarticular complications be identified and managed.
Formal instruction in proper posture and exercises emphasizing spinal mobility and strengthening of muscles is important. Range of motion exercises for the neck, shoulders and hips as well as deep-breathing exercises to maintain chest expansion should be performed by the patient daily. Of all therapeutic modalities only regular exercise has been shown to curtail progression of spinal stiffness and restriction.
Treatments with non-steroidal anti-inflammatory medicines may reduce spinal stiffness. For extreme cases stronger therapies can be instituted.