The radiological diagnosis of tuberculosis of the adult spine.

Tuberculosis remains endemic in the United States with an estimated incidence of 15.9 cases per 100,000 population. In North America and Saudi Arabia tuberculosis of the spine is primarily a disease of adults. In Saudi Arabia the average age on presentation is 41 years. Spinal tuberculosis begins classically in the anterior inferior portion of a vertebral body. The infection spreads beneath the anterior longitudinal ligament to involve adjacent vertebral bodies. Disc space narrowing is a secondary phenomenon, occurring when destruction of the cancellous bone permits herniation of the disc into the affected vertebral body. Initially the lesion is purely lytic, so that in the early phase bone scanning, both with technetium polyphosphate and gallium, is often negative. With combination chemotherapy virtually all patients are curable, but early treatment demands early diagnosis. As the incidence of Pott disease has decreased so too has the medical awareness of this condition. Many physicians now believe it to have been totally eradicated. Particularly in the older age group, in whom other infections, tumours, and metabolic conditions are common, the differential diagnosis of a spinal lesion should include tuberculosis. The grossly destructive changes observed characteristically in children tend to develop only late in adults, making recognition of the early manifestations of the infection in the older patient much more important.