THE EPIDEMIOLOGY OF SPONDYLODISCITIS IN ANKYLOSING-SPONDYLITIS - A CONTROLLED-STUDY

Spondylodiscitis is well recognized in ankylosing spondylitis (AS), bu t little is known about its epidemiology. We therefore reviewed 147 co nsecutive patients with AS using lumbar and thoracic spine radiographs . For each patient with spondylodiscitis, two age- and sex-matched con trols were selected. Twelve individuals (8%) had spondylodiscitis, aff ecting a total of 32 disc spaces: 10 thoracic, 22 lumbar. The mean age at onset was 21 +/- 4.1 yr, significantly younger than that of the co ntrols (28.5 +/- 10.1 yr, P = 0.004). Half of the 12 patients had mult iple lesions (between two and six levels). The most common site was th e lower thoracic spine with additional lumbar spine involvement. Only two of the 12 patients (17%) had symptoms localized to the lesions. Ne ither trauma nor infection were considered to be causes of the spondyl odiscitis. In conclusion: (1) spondylodiscitis occurs in similar to 8% of patients with AS; (2) these patients have early onset of disease; (3) multiple-level lesions in the spine are not uncommon among those w ith spondylodiscitis; (4) lesions are usually asymptomatic.