Brucellosis often affects the musculoskeletal system and is included in the differential diagnosis of variety of clinical pictures
7,8. Osteoarticular complications of brucellosis occur in 10%-85% patients
9-12. The spine is the most common affected site and back pain is the most common clinical manifestation of brucellosis
11,13-15. Colmenero et al. found that; spondylitis occured in 58%, sacroiliitis in 45% of their patients who had osteoarticular complications of brucellosis
16.
Sacroiliitis of brucellosis usually occurs unilaterally in young patients, and is asymmetric in cases with bilateral involvement.1,7,12,17. In brucellosis, there is no radiologic progression changes and ankylosis in sacroiliac joint and it is resolved the problem without residual damage1,7,8. Taşova et al. reported that sacroiliitis has been determined as the most frequently osteoarticular complication of brucellosis in Turkey. They found that concomitant sacroiliitis and spondylitis were only in 6 of 238 patients7. Sacroiliitis is significantly associated with lumbar or sacral spondylitis in the elderly patients4.
Brucellar spondylitis may be difficult to diagnose and can be concomitant with connective tissue diseases and spondylarthropathies and changes in plain radiographs can be difficult to differentiate from degenerative diseases8-10. The incidence of spondylitis reported in the literature ranges from 10% to 50%. İt is seen especially in elderly men over 50 years of age7,14,18,19.
If both sacroiliitis and spondylitis are seen in young patients, the noninfectious causes of sacroiliitis and spondylitis should be considered. Most patients with brucellar spondylitis and sacroiliitis respond to antibiotic treatment10,14. Sacroiliitis and spondilitis are not related to the presence of HLA-B27 antigen4 but HLA B27 was positive in our case. Additionally our patient has bilateral simetric sacroiliitis and spondilitis which did not respond to antibiotic treatment.
Destructive lesions of spondylodiscitis involving an intervertebral disc space and adjoining vertebral bodies are seen in AS. Radiological estimates of the prevalence of spondylodiscitis are reported in a range of 1-28%. Destructive change at the discovertebral junction may be predominately peripheral, central or both. Spondylodiscitis in AS is often asymptomatic20,21. But if an AS patient presents pain increasing after movements and improving at rest, spondilodiscitis should be considered21. The low back pain in brucellosis does not reduce with rest and exercise8. As in our case, the altering character of the inflammatory low back pain in the presence of spondilodiscitis in the patients with spondylitis leads to difficulties in differential diagnosis.
MRI plays an important role in the diagnosis, assesment, and management of patients with spondylitis10. MRI is noninvasive, involves no radiation exposure and provides excellent multiplanar views of osseous and soft tissues2,22. In the spine, MRI findings of AS includes sacroiliitis, spondylodiscitis, pseudoarthrosis, fractures, atlantoaxial subluxation, ossification of ligaments and cauda equina syndrome. The spectrum of infections of the spinal column includes vertebral osteomyelitis, discitis and paravertebral and epidural phlegmon or abscess2.
After successfull treatment of infectious spondylitis, the MRI findings slowly change to normal2. But in our case, the spine involvement had the characteristics of spondylarthropathy, the radiologic progress was continued in spite of the treatment, bilateral and symmetric sacroiliitis was present and HLA-B27 was positive. In the light of these clinical findings, the lesion at L2-L3 vertebrae was accepted as ‘spondilodiscitis' associated with AS.
In conclusion, in endemic regions, coexistance with AS and brucellosis should always be in mind of the physicians and diagnosis of brucellosis alone should not be regarded as satisfying all the time especially in cases resistant to trea.