Diskitis is an intervertebral disk space infection that does not cause associated vertebral osteomyelitis (see Chapter 117). The most common organism is Staphylococcus aureus. The infection can occur at any age but is more common in patients under 6 years of age.
Children may present with back pain, abdominal pain, pelvic pain, irritability, and refusal to walk. Fever is an inconsistent symptom. The child typically holds the spine in a straight or stiff position, generally has a loss of lumbar lordosis due to paravertebral muscular spasm, and refuses to flex the lumbar spine. The white blood cell count is normal or elevated, but the ESR is usually high.
Radiographic findings vary according to the duration of symptoms prior to diagnosis. Anteroposterior, lateral, and oblique radiographs of the lumbar or thoracic spine will typically show a narrow disk space with irregularity of the adjacent vertebral body end plates. In early cases, bone scan or MRI may be helpful, because they will be positive before findings are noticeable on plain radiographs. MRI can also be used to differentiate between diskitis and the more serious condition of vertebral osteomyelitis.
Intravenous antibiotic therapy is the mainstay of treatment. Blood cultures may occasionally be positive and identify the infectious agent. Aspiration and needle biopsy are reserved for children who are not responding to empirical antibiotic treatment. Symptoms should resolve rapidly with antibiotics, but intravenous antibiotics should be continued for 1 to 2 weeks, and be followed by 4 weeks of oral antibiotics. Pain control can be obtained with medications and temporary orthotic immobilization of the back.