The incidence of tuberculosis is increasing. The factors responsible are the increase in the number of immunocompromised persons, the development of drug-resistant strains of Mycobacterium tuberculosis and the aging of the population. HIV is the main risk factor for reactivation of latent TB infections. The World Health Organization estimates that one-third of the world’s population is infected with this organism and that it is the most common cause of death and disability in the world. Approximately one-fifth of newly diagnosed cases are extrapulmonary, and the spine is involved in 50% of cases of bone and joint TB.

Tuberculosis (TB) as a disease has been known since antiquity. In 1779, Sir Percival Pott described that tubercular disease of the spine clinically presents with kyphotic deformity and neurological deficit in European patients. [1]

Later in the and 20th centuries, the discovery of the underlying pathogenic microorganism (Mycobacterium tuberculosis), the development of the Bacillus Calmette-Guérin (BCG) vaccine, advances in diagnostic modalities, chemotherapeutic agents, and surgical procedures largely revolutionized the management of spinal tuberculosis and provided humanity with much better protection against this debilitating disease.

Recently, the disease has shown a significant resurgence in developed countries, particularly among the immunocompromised population secondary to a “global migration phenomenon.” This has posed a significant challenge to the global community.

Epidemiology

Tuberculosis is the leading cause of death in the world from a single infectious agent. The number of new cases worldwide is closely correlated with the economic conditions of the country.

  • 8 million people contract TB each year, 95% of whom live in developing countries
  • An estimated 2 million people worldwide have active spinal TB

Predisposing factors

  • Malnutrition
  • Poor sanitation
  • Overcrowding
  • Close contact with a TB patient
  • Multiple pregnancies
  • Immunodeficiency status

Vertebral Tuberculosis

  • Tuberculosis becomes established in the vertebra through blood transport from a primary site of infection
  • This primary site of infection is often the lungs.
  • The paradiscal vessels usually supply the subchondral bone on either side of the disc space and, therefore, the most common site of spinal involvement is paradiscal.
  • Other types of involvement include central (with predominant involvement of the vertebral body), posterior (primarily involving the posterior structures), and nonbony (presenting with an abscess). [13] [14] Progressive vertebral destruction results in kyphotic deformity and instability of the spine.

Causes

  • The underlying pathogen of tuberculosis is Mycobacterium.
  • There are approximately 60 species, of which M. tuberculosis is the most common type.
  • These organisms are fastidious, slow growing, aerobic bacilli.
  • Tuberculosis bacilli are capable of remaining dormant for a long period of time; however, when favorable conditions return, they tend to multiply once every 15 to 20 hours. [9]
  • Infection results in a granulomatous inflammatory reaction, which is usually characterized by necrosis. [10]
  • Some known risk factors for tuberculosis include prolonged exposure to infected patients, immune deficiencies (HIV, alcohol, drug abuse), overcrowding, malnutrition, poverty and poor socioeconomic status.

Regional distribution of spinal tuberculosis

  • Cervical – 12%
  • Cervicodorsal – 5%
  • Dorsal – 42%
  • Dorsolumbar – 12%
  • Lumbar – 26%
  • Lumbosacral – 3%

Types of tubercular lesions in the spine

There are four types of lesions:

  1. Paradiscal
    • The most common
    • The contagious area of two adjacent vertebrae with the disc is affected.
    • This is because the lower half of a vertebra and the upper half of a vertebra below with the disc in between, grow from each pair of sclerotomes and therefore have a common blood supply.
  2. Anterior
    • Infection begins below the anterior longitudinal ligament and involves the anterior margin of the vertebral body.
    • The infection may spread up and down under the anterior longitudinal ligament.
    • The pus that accumulates in this area often on x-ray gives the appearance of an aortic aneurysm, thus called “Aneurysmal Phenomena”.
  3. Central
    • The body of a vertebra is affected.
    • In this infection, the disc space is preserved.
    • The whole vertebrae collapses in the later stages leading to an “accordion-like collapse”.
  4. Appendicular
    • Posterior involvement is rare and involves the pedicles, laminae, transverse process, facet joints and spinous process.
    • The facet joints followed by the spinous process are the structures least frequently involved in the posterior type.
Tubercular lesion in the spine

 

Radiograph

  • Reduced disc space
  • Destruction of the vertebral body
  • Loss of trabecular pattern
  • Increased shadowing of the prevertebral soft tissue
  • Subluxation / dislocation
  • Decreased lordosis / kyphosis

Reference

  1. Tuli SM. Historical aspects of Pott’s disease (spinal tuberculosis) management. Eur Spine J. 2013 Jun;22 Suppl 4:529-38. [PMC free article] [PubMed]
  2. Dobson J. Percivall Pott. Ann R Coll Surg Engl. 1972 Jan;50(1):54-65. [PMC free article] [PubMed]
  3. Oettinger T, Jørgensen M, Ladefoged A, Hasløv K, Andersen P. Development of the Mycobacterium bovis BCG vaccine: review of the historical and biochemical evidence for a genealogical tree. Tuber Lung Dis. 1999;79(4):243-50. [PubMed]
  4. McLain RF, Isada C. Spinal tuberculosis deserves a place on the radar screen. Cleve Clin J Med. 2004 Jul;71(7):537-9, 543-9. [PubMed]
  5. Arockiaraj J, Karthik R, Michael JS, Amritanand R, David KS, Krishnan V, Sundararaj GD. ‘Need of the Hour’: Early Diagnosis and Management of Multidrug Resistant Tuberculosis of the Spine: An Analysis of 30 Patients from a “High Multidrug Resistant Tuberculosis Burden” Country. Asian Spine J. 2019 Apr;13(2):265-271. [PMC free article] [PubMed]
  6. Rajasekaran S, Soundararajan DCR, Shetty AP, Kanna RM. Spinal Tuberculosis: Current Concepts. Global Spine J. 2018 Dec;8(4 Suppl):96S-108S. [PMC free article] [PubMed]
  7. Shetty AP, Viswanathan VK, Kanna RM, Shanmuganathan R. Tubercular spondylodiscitis in elderly is a more severe disease: a report of 66 consecutive patients. Eur Spine J. 2017 Dec;26(12):3178-3186. [PubMed]
  8. Jain AK, Dhammi IK. Tuberculosis of the spine: a review. Clin Orthop Relat Res. 2007 Jul;460:39-49. [PubMed]
  9. Rasouli MR, Mirkoohi M, Vaccaro AR, Yarandi KK, Rahimi-Movaghar V. Spinal tuberculosis: diagnosis and management. Asian Spine J. 2012 Dec;6(4):294-308. [PMC free article] [PubMed]
  10. Jain AK. Tuberculosis of spine: Research evidence to treatment guidelines. Indian J Orthop. 2016 Jan-Feb;50(1):3-9. [PMC free article] [PubMed]

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