Clinical manifestations of ankylosing spondylitis

Abstract

The main clinical symptoms in AS are pain and stiffness of the back, predominantly of the lower back and the pelvis, but any part of the spine can be involved. Typical for AS/spondyloarthritis (SpA) is inflammatory back pain (IBP) which is defined clinically and not by laboratory tests such as C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR). Patients complain about morning stiffness of the back, with improvement on exercise but not by rest. In addition, or alternatively, they report awakening at night, mostly in the second half of the night, because of back pain which improves on getting up and moving around (Figure 3.1). Furthermore, back pain should be chronic (>3 months duration) not acute, and it should occur for the first time before the age of 45 years, because the disease starts at a young age; this also helps to differentiate it from degenerative spine disease, the prevalence of which increases with age. Most patients report a mixture of pain and stiffness in the spine, although either can be the main or only symptom.