Teaching Case

A 75-year-old man visited the outpatient department complaining of back pain that localized to the mid-lower dorsal region. Additionally, he had a nocturnal fever of 39°C for the last month or so, accompanied by fatigue, headaches, and anorexia. Physical examination revealed localized tenderness over the pointed area in the back. Preliminary lab results elicited CRP at 39 mg/L & Brucella agglutination test was 1/320. Hence, a blood culture was ordered, which was positive for the growth of the brucella microorganism.

A standard MRI scan of the dorsolumber spine was performed as the best imaging modality for the assessment of back pain especially when the plane radiograph was clueless.

The MRI scan showed a localized signal abnormality limited to T8 and T9 levels in terms of diffusely hypointense signal T1 (Figures 1 and 2) that reciprocally highlighted as a hyperintense signal on the fat-saturated STIR sequence (Figure 3) bone marrow changes within the vertebral bodies along with focal endplate erosion without significant visible change in the subjacent intervertebral disc. The findings were nonspecific but suggestive of infection rather than neoplastic and infiltrative processes. Nevertheless, when combined with clinical history and blood profile, and the patient being from an endemic area, they were all quite coherent with brucella spondylitis.

An old healed T11 vertebral body wedged fracture in the background of the ageing process-related features was depicted in addition. However, there were no signs of extraosseous extension of the disease process to the paravertebral soft tissue, epidural space, and posterior neural arch (Figures 4 and 5). And no further similar foci were appreciated at other levels of the spine.

The contents of the spinal canal (spinal cord, thecal sac, and subarachnoid spaces) were unremarkable.

Background

Brucellosis is a chronic granulomatous febrile illness caused by gram-negative bacteria approaching the human body through ingestion of contaminated unpasteurized dairy products and to a lesser extent undercooked meat. It is prevalent around the Mediterranean Sea. The infection attacks any system; however, it is notorious to have musculoskeletal affinity in 20-30% with more particular spine and sacroiliac joint involvement [1].

Clinical perspective

The cardinal feature of the disease is fever (hence the disease also referred to as Malta fever and undulant fever) in addition to fatigue, muscle, joint pain, and backache. Malaise, poor appetite, and anaemia are among other general manifestations of systemic brucellosis.

The laboratory diagnostic tests are plenty, including agglutination test (more than 1/160 is significant), serological tests like ELIZA, Immunological tests like antigen and antibodies, 2ME (Mercapto Ethanol) reactive test, growth/isolation of bacteria on blood culture, raised C-reactive protein, white blood cell count and erythrocyte sedimentation rate, and detection of the organism by PCR (polymerase chain reaction) test on blood, body fluid, and tissue sample. Any positive check test in the appropriate clinical setting is highly significant to consolidate the diagnosis of Brucellosis [2].

Imaging perspective

Diagnosis of osteoarticular brucellosis is tricky without clinical background history provided. MRI is the most sensitive modality to evaluate for spinal brucellosis, nevertheless, veracious pieces of information can be obtained from bone scans, CT scans, and even radiographs at different phases of the disease. Brucella can affect the spine in unifocal or multifocal fashion. There are at least 5 patterns of affection, these include osteomyelitis, diskitis, adnexitis, soft tissue epidural, and paravertebral psoas abscess [3]. The lower lumber level is the most affected, usually, the infection starts in the endplate owing to the rich vascularity, followed by multidirectional spread to the disc, ligament vertebral body bone marrow, and extraosseous contagious tissue. Abnormal heterogeneous signals with low T1 / high T2 sequence which is bright on the FAT SAT sequence signify acute stage due to inflammatory oedema in the involved structures. Enhancement following IV contrast is heterogeneous and more peripheral when there is abscess collection. In chronic stages, reduced disc height, sclerosis, erosion, and vertebral collapse could be pursued if no treatment is introduced [4].

Outcome

As the infection is caused by intracellular microorganisms, antibiotic therapy with a combination of agents is important for a median duration of 120 days to achieve remission [5]. Surgical intervention and drainage may be required in more complicated cases such as abscess formation or marked destruction necessitating stabilization. Our patient reported a gradual symptomatic response to the medical anti-brucella treatment, his follow-up inflammatory marker had significantly dropped down (CRP at 10 mg/L after one month), and he became completely symptom-free after three months of consistent therapy.

Take Home Message

To arrive at the exact diagnosis and hence appropriate management with the ultimate best prognosis of Brucella spondylitis, the imaging protests demand interpretation in the full clinical context in conjunction with laboratory affirm.

Written informed patient consent for publication has been obtained.