Vertebral Osteomyelitis/Discitis

Epidemiology

The incidence of bacterial vertebral osteomyelitis/discitis typically affects adults, with a slight male predominance. Immunocompromised patients, drug abusers, and patients with head and neck infections are at greatest risk. The incidence of postoperative discitis ranges from 0.2 to 0.3%.

Clinical Features

The most common clinical presentation is neck pain followed by fever. However, up to 40% of patients may be afebrile. The onset is usually acute. Paresthesias may occur if there is periradicular inflammatory extension of the infection. Neurological deficit may occur in advanced cases that are associated with epidural phlegmon or abscess.

Pathology

Staphylococcus aureus is the most common pyogenic organism in adults. The infection is believed to reach the spine by hematogenous spread rather than by direct extension from adjacent soft tissue infection. The dominant cell is the polymorphonuclear leukocyte.

In children, the disc is richly vascularized and is the initial site of infection. Hematogenous spread to anastomosing arteries located at the metaphyseal end plates and intermetaphyseal anastomoses with arteries of the adjacent vertebrae predispose children to an initial discitis. The infections then extend to the adjacent vertebral end plates.