Abstract 716

Background: Vertebral osteomyelitis and discitis are distinct entities, but their similar clinical presentation may create diagnostic difficulty. Also, a comparative review of patients with these diagnosis has never been performed. Objective: To determine the usefulness of MRI in the diagnosis of discitis and vertebral osteomyelitis, since both are characterized clinically by back pain and refusal to walk. Method: A retrospective medical record review was conducted of patients with a discharge diagnostic of discitis or vertebral osteomyelitis hospitalized at Texas Children's Hospital from January, 1980 through October, 1998. Results: There were 49 patients who met our inclusion criteria, 36 with discitis and 13 with vertebral osteomyelitis. The mean age at presentation was younger for children with discitis than for those with vertebral osteomyelitis (2.8 vs 7.1 yrs; P=0.002), and the duration of symptoms longer for children with vertebral osteomyelitis than for those with discitis (33 vs 22 days; P=0.04). The results of the white blood cell count, erythrocyte sedimentation rate, and technetium 99 bone scan in these 49 patients were non-specific, and did not distinguish between these two entities. Of the 13 patients with vertebral osteomyelitis, 11 had MRI and all studies were abnormal, establishing the diagnosis. Among these 11 patients, 10 also had radiographs of the lumbar spine; and 8 of these were normal. Of the 36 patients with discitis, 33 had radiographs of the spine and 25 (73%) revealed abnormalities consistent with the diagnosis. Ten patients with discitis had MRI, and 9 (90%) had abnormalities consistent with the diagnosis. Discitis patients who had MRI were more likely to undergo biopsy or needle aspiration of the disc space than those who did not have MRI (80% vs 4%). Conclusion: MRI is the diagnostic study of choice for pediatric patients with suspected vertebral osteomyelitis, while radiographs of the lumbar spine usually are sufficient to establish a diagnosis of discitis. Abnormalities detected by MRI in patients with discitis actually may promote invasive procedures historically not required for the treatment of this typically self-limited process.