Asymptomatic brain abscess as a complication of halo orthosis: report of a case and review of the literature.

The halo external orthosis has been used extensively for cervical immobilization after spine surgery or trauma, usually without serious complications. However, nine brain abscesses have been reported as complications following the use of halo orthosis. We report on a 53-year-old man who underwent anterior cervical fusion for cervical myelopathy, followed by the application of a halo orthosis. Approximately 4 weeks postfusion, loosening of the right anterior pin was recognized and the pin was tightened, as the pin-site was clean. One week later, purulent material was discharged from the pin hole when the pin was removed after it had loosened again. Enhanced computed tomography (CT) demonstrated an abscess on the right side of the brain. After the administration of antibiotics, the abscess resolved without surgical intervention. We describe asymptomatic brain abscess complicating the use of a halo orthosis and review the clinical features, symptoms, and outcomes; we also discuss the mechanism that induced brain abscess. Most reported cases of abscess have been associated with pin-site infection or tightening after late pin loosening. The present case indicates the importance of early recognition of symptoms and signs associated with brain abscess in patients with a halo orthosis.