Tuberculosis can hollow out the spine while an abscess stays cold
Pott's disease is tuberculosis that has travelled through the bloodstream into the vertebrae, usually from the lungs. It can collapse discs and bend the spine forward, and the abscesses it forms are called cold because they lack the heat and redness of ordinary infection. A British surgeon described it in 1779.
Percivall Pott, whose name the disease carries, set out its symptoms in 1779. It most often strikes the lower thoracic and upper lumbar spine. Bacteria enter the spongy bone of a vertebra through the arteries serving the front and back of the spine and attack the front of the vertebral body. When two neighbouring vertebrae are infected, the disc between them, which has no blood supply of its own, is starved, dies through caseous necrosis and collapses. Collapse of the front of the spine produces kyphosis, a forward curve, more often when the thoracic region is involved.
Back pain that worsens with activity is the earliest and most common sign, followed by nerve problems whose pattern depends on location: neck infections can affect arms and legs, lower-back infections mainly the legs and the area around the tailbone. Cold abscesses can grow large; in the neck one may press on the throat and affect swallowing or the voice, and in the lower back one can track down the psoas muscle towards the thigh. Symptoms creep in slowly, with an average delay before diagnosis historically of at least a year, recently shortened to three to six months.
Early detection is hard with ordinary X-rays, because a lesion only becomes visible after about 30 percent of bone mineral is lost; MRI performs better. Certainty requires growing the bacterium in culture and testing which drugs it responds to. Children are affected more often because their spines have a richer blood supply, and their curvature can worsen during growth spurts even after the infection is no longer active.
About 2 percent of all tuberculosis cases involve the spine in this way, making up roughly half of tuberculosis in bones and joints. Risk rises with HIV and other causes of weakened immunity, undernourishment, crowded and poorly ventilated housing, and poverty. Low vitamin D has also been linked with higher risk. In wealthy countries such as the United States it mainly affects adults, while in developing countries it is concentrated among older children and young adults.
Source: Pott's disease
