Pott's disease

Pott's disease, named for British surgeon Percivall Pott who first described the symptoms in 1799, also known as Pott disease is tuberculosis of the spine, usually due to haematogenous spread from other sites, often the lungs. The lower thoracic and upper lumbar vertebrae areas of the spine are most often affected. It causes a kind of tuberculous arthritis of the intervertebral joints. The infection can spread from two adjacent vertebrae into the adjoining intervertebral disc space. If only one vertebra is affected, the disc is normal, but if two are involved, the disc, which is avascular, cannot receive nutrients, and collapses. In a process called caseous necrosis, the disc tissue dies, leading to vertebral narrowing and eventually to vertebral collapse and spinal damage. A dry soft-tissue mass often forms and superinfection is rare. Spread of infection from the lumbar vertebrae to the psoas muscle, causing abscesses, is not uncommon. Blood tests – Complete blood count: leukocytosis – Elevated erythrocyte sedimentation rate: >100 mm/h Tuberculin skin test – Tuberculin skin test (purified protein derivative [PPD]) results are positive in 84–95% of patients with Pott disease who are not infected with HIV. Radiographs of the spine – Radiographic changes associated with Pott disease present relatively late. These radiographic changes are characteristic of spinal tuberculosis on plain radiography: Lytic destruction of anterior portion of vertebral body Increased anterior wedging Collapse of vertebral body Reactive sclerosis on a progressive lytic process Enlarged psoas shadow with or without calcification – Additional radiographic findings may include: Vertebral end plates are osteoporotic Intervertebral disks may be shrunken or destroyed Vertebral bodies show variable degrees of destruction Fusiform paravertebral shadows suggest abscess formation Bone lesions may occur at more than one level Bone scan Computed tomography of the spine Bone biopsy MRI Controlling the spread of tuberculosis infection can prevent tuberculous spondylitis and arthritis.