Infectious spondylitis.

Infection of the spine is a rare but serious cause of back pain. Conventional radiographs remain the initial screening procedure. Typically two adjacent vertebral bodies and the intervening disk space are affected. Early in the course of the disease, radiographs may be normal or nondiagnostic. Magnetic resonance imaging or radionuclide bone scan will establish pathology centered in the vertebral body. Because of the ability to image soft tissues, magnetic resonance imaging is particularly helpful in detecting paravertebral and extradural abscesses. Four other conditions may mimic infectious spondylitis: degenerative disk disease associated with Modic type 1 changes, pseudoarthrosis in ankylosing spondylitis, dialysis spondyloarthropathy, and neuropathic spondyloarthropathy. Advanced imaging studies in combination with radiographs and clinical information are essential in determining the correct diagnosis.