Imaging does not predict the clinical outcome of bacterial vertebral osteomyelitis

Objectives. Magnetic resonance imaging (MRI) and computed tomography (CT) are useful for initial assessment of bacterial spondylodiscitis. However, clinical relevance of imaging changes during treatment is less well-documented. Methods. Between October 1997 and March 2005, 29 patients with documented bacterial spondylodiscitis were prospectively enrolled. They had clinical, biological and imaging examinations (MRI and/or CT) at M0 and M3, and in 22 cases, at M6. Results. Mean age was 58 yrs. Antimicrobial chemotherapy lasted an average of 98 days. The median follow-up was 18 months, including 12 months after the completion of treatment. Infection was cured in every patient. Biological markers of inflammation returned to normal at M3. Six patients had painful and/or neurological sequelae. Decreased disc height was a consistent and early sign, and remained stable during the follow-up. Vertebral oedema, present in 100% of cases initially, persisted in 67 and 15% of cases at M3 and M6, respectively. Discal abscesses and paravertebral abscesses, present in 65 and 39% of cases initially, persisted in, respectively, 42 and 9% of cases at M3 and in 18 and 3% of cases at M6. Epidural abscesses were present at diagnosis in 30% of cases, and had always disappeared by M3. Imaging abnormalities found at M0 and M3 did not differ between patients with and without late neurological or painful sequelae. Conclusions. Imaging abnormalities often persist in patients with bacterial spondylodiscitis despite a favourable clinical and biological response to antibiotic treatment. They are not associated with relapses, neurological sequelae or persistent pain. Imaging controls are not necessary when bacterial spondylodiscitis responds favourably to treatment.