When large vertebral segments or multiple segments with intervening normal zones are present, the paravertebral venous plexus of Batson is implicated. Bony changes are seen two to five months after infection. Usually, the subchondral regions of the vertebral body are affected. When the anterior and lateral portions of the vertebral body are affected, vertebral collapse occurs resulting in kyphosis and gibbus deformity. Involvement of the posterior vertebral body results in cavitation and an extradural mass.
Kyphosis occurs in the thoracic spine while the lumbar spine telescopes on itself as it collapses.
The disc space is eventually destroyed, but at a slower rate than pyogenic infection. Tuberculosis can spread from a spinal focus by direct extension through the disc space. From the cervical vertebrae the disease can travel to the posterior triangle of the neck or retropharnyx. The abscess can also track along fascial planes to create a psoas abscess or can extend posteriorly to form an extradural abscess. Clinically patients present with pain over the affected vertebra, low grade fever, chills, weight loss.