Pott's disease overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Pott's disease or Pott disease is a presentation of extrapulmonary tuberculosis that affects the spine. The lower thoracic and upper lumbar vertebrae are most commonly affected. Scientifically, it is called tuberculous spondylitis and it is most commonly localized in the thoracic portion of the spine. Pott’s disease results from haematogenous spread of tuberculosis from other sites, often pulmonary. The infection then spreads 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. The disc tissue dies and is broken down by caseation, leading to vertebral narrowing and eventually to vertebral collapse and spinal cord compression.
Historical Perspective
Pott's disease is named after Percivall Pott (1714–1788), a London surgeon who trained at St Bartholomew's Hospital, London.
Pathophysiology
Pott's disease occurs usually due to hematogenous spread of tuberculous infection from a pulmonary or genitounrinary site. Pott's disease usually involves more than one vertebra and manifests as a combination of osteomyelitis and arthritis. The involvement of the vertebra can be contiguous or non-contiguous based on the mode of spread.
Causes
Pott's disease is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the spine, kidney, and brain. Pott's disease is a presentation of extrapulmonary tuberculosis that affects the spine.
Differentiating Pott's Disease from other Diseases
Pott's disease resembles spinal tumors, spinal cord abscess, Mycobacterium kansasii, nocardiosis, septic arthritis, metastatic cancer, multiple myeloma, miliary tuberculosis, spinal fungal infections, and Mycobacterium avium-intracellulare and needs to be differentiated from them.
Risk Factors
Pott's disease develops in the small number of infected people whose immune systems do not successfully contain the primary infection. Pott's disease can occur within weeks of the primary infection. Sometimes, it does not occur until years after you become infected. You are more likely to get this type of TB if you have a weaken immune system due to disease (such as AIDS) or certain medications. Infants and the elderly are also at higher risk.
Natural History, Complications and Prognosis
Pott's disease may be complicated by severe vertebral deformity and collapse resulting in kyphosis, cord compression, sinus formation, and paraplegia. However, it responds well to treatment, if it is not complicated by severe deformity or established neurologic deficit.
Diagnosis
History and Symptoms
The history and symptoms of Pott's disease depends upon the stage of disease, affected site, and presence of complications. Back pain is the earliest and most common symptom of Pott's disease. Other constitutional symptoms include fever, night sweating, anorexia, and weight loss.
CT
CT scan of spine provides much precise bony details of vertebral bodies, intervertebral disks, sclerosis, and osteoporotic vertebral end plates. It is helpful to detect early lesions and is more effective for defining the shape and calcification of soft-tissue abscesses.
Other Imaging Findings
Radionuclide bone scanning may be done, but findings are not specific for Pott's disease.
Treatment
Medical Therapy
Pott's disease can be treated with antituberculous drugs and should be closely monitored to assess the response to therapy and compliance with medication. To effectively treat Pott's disease, it is crucial that patients take their medications exactly as prescribed.
Primary Prevention
Pott's disease can be prevented by controlling the spread of tuberculosis infection. Patients who have a positive PPD test (but not active tuberculosis) may decrease their risk by properly taking medicines to prevent tuberculosis.