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      When tuberculous infection spreads to the spine it can cause severe back pain. As the disease progresses it can cause deformity of the spine and can lead to paralysis due to pressure on the cord by pus and bony destruction. Although the condition is serious it is treatable.

      Tuberculosis is an infection caused by the bacterium Mycobacterium tuberculosis and one of the leading causes of mortality worldwide. It is seen more commonly in low and middle income countries. Tuberculosis can be prevented and if diagnosed early can be cured

      TB primarily affects the lungs (pulmonary tuberculosis), but spreads via the blood stream to other parts of the body, and this is referred to as extrapulmonary tuberculosis (EPTB) such as the bones, kidneys and bowel.

      The most commonly involved bone in extrapulmonary tuberculosis is the spine and TB spine is also termed Pott’s disease and accounts for nearly 50% of bone and joint TB in developing countries.

      In the last few decades, the incidence of bone TB has increased due to spread of AIDS (since these patients are susceptible to TB). Spine TB is difficult to diagnose and can cause complications if not treated in time.

      The common parts involved in Pott’s disease are the lower thoracic and upper lumbar vertebrae. Usually more than one vertebra is involved and the anterior part of the vertebral body is usually affected. It can spread from the vertebral body to the adjacent intervertebral disc. If the disc is involved, it collapses with narrowing of the intervertebral space and spinal injury

      PATHOGENESIS OF TB SPINE
      • Tuberculous infection of spine is thought to occur from foci of bacilli that lodge in the spine during the initial hematogenous dissemination of the mycobacteria. The primary focus may either be active or quiescent, either in the lungs, mediastinal lymph glands, mesentery, kidney or other organs.

      • Also, tuberculous bacilli may spread from the lung to the spine by Bateson’s paravertebral venous plexus or lymphatic drainage to the para-aortic lymph nodes.

      • In most otherwise healthy persons, the T-cell mediated immune response is able to contain the bacilli in these sites, but not completely eradicate them

      RISK FACTORS
      • Poor hygiene and socioeconomic conditions such as overcrowding
      • Living in areas having high prevalence of TB
      • Immunosuppressed state such as HIV infection

      SIGNS & SYMPTOMS OF POTT’S DISEASE
      In early stages, when the infection is confined to a single vertebral body and adjacent paraspinal soft tissue, the symptoms include
      • chronic illness
      • generalized tiredness and lethargy
      • low grade fever and night sweats
      • weight loss
      • severe back pain and swelling (associated with bone destruction)
      • stiffness and reduced movement of spine (inability to bend)
      • paraspinal abscess formation with pain and swelling

      In advanced stages, symptoms can be serious and include
      • neurological complications such as weakness and paresthesia (10-50% cases)
      • paraplegia/paralysis
      • visible spinal deformities (kyphosis)

      DIAGNOSIS OF SPINAL TB
      • Full blood count may show relative lymphocytosis and low hemoglobin
      • Raised ESR
      • Usually strongly positive tuberculin (Mantoux) skin test
      • X-ray spine may not show any changes in early disease, as about 50% of bone density should lost to be evident on x-ray. It may reveal damaged vertebral body and narrowed disc space
      • MRI scans can show extent of spinal compression and other bony changes earlier. Bony elements
      visible inside the swelling, or mass, is more likely to be tuberculosis rather than malignancy.
      • Although CT scans and nuclear bone scans may be done, MRI is the most ideal test to assess spinal disease and damage
      • If needle biopsy of bone or synovial tissue demonstrates tubercle bacilli, it confirms the diagnosis but usually culture is required to establish diagnosis and must include a fungal culture also
      • Patients with spinal TB must undergo chest x-ray and if possible sputum test to exclude lung TB as well as tests to rule out tuberculosis in other parts of the body

      DIFFERENTIAL DIAGNOSIS
      Other conditions that may have a similar presentation should be considered in the differential diagnosis and excluded
      Osteomyelitis of spine – caused by atypical bacteria (eg Nocardia asteroides, Actinomyces israelii), fungi or spirochetes
      Spinal tumors

      COMPLICATIONS OF SPINAL TB
      • Progressive destruction of vertebrae with collapse and kyphosis. Lesions of the thoracic spins carry a greater risk of kyphosis than lumbar spinal lesions. Early treatment with chemotherapy and surgical decompression is associated with the most favorable outcomes
      • Narrowing of spinal canal (spinal stenosis) by abscess and inflammation with evidence of cord compression and neurological deficits (including weakness and paralysis)
      • Formation of cold abscess in the paraspinal soft tissue in the lumbar spine which can track down the psoas sheath to the femoral trigone area and erode the skin forming sinuses

      TREATMENT OF SPINAL TB
      • Antituberculous treatment is the mainstay in cases with no spinal deformity /neurological deficit
      • Prolonged rest and immobilization of spine for two to three months.
      • Surgery is reserved for those cases where neurological deficit is not improved by anti-tubercular treatment and there is progression of spinal deformity

      Medical treatment
      • The most commonly antitubercular drugs used include isoniazid (H), rifampin (R), ethambutol (E) and pyrazinamide (Z) therapy. The regimen is RHZE for 2 months, then RH for 9 to 18 months

      • Spinal brace or orthosis may be used to control back pain and prevent deformity

      Surgical treatment
      • Referral for surgery is indicated if there is evidence of spinal cord compression or spinal instability
      • Additional indications for surgery include patients with kyphosis of 60° or more (or a deformity thought more likely to progress. Surgery includes anterior decompression, posterior shortening, and stabilization with anterior and posterior bone grafting during the active stage of the disease

      PROGNOSIS
      TB spine is a chronic condition that develops gradually and may last for months to years. Patient outcome is better with early diagnosis and treatment and latest regimens of chemotherapy

      PREVENTION
      • BCG vaccination
      • Prevention and early treatment of HIV/AIDS
      • Improving socioeconomic and sanitary conditions and preventing overcrowding

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