This image illustrates the gross skeletal damage that can result from disseminated tuberculosis. The picture was taken at the Museum of Medical History, University of Copenhagen, in Denmark. The skeleton was dated to the 16-17th centuries. This image can be used to illustrate the disseminated form of tuberculosis.

Although 85% of tuberculosis deaths are caused by pulmonary infection, disseminated, or non-pulmonary, disease can have severe consequences; the pathogenesis is particularly severe among children. Both the pulmonary and non-pulmonary infections are caused by Mycobacterium tuberculosis; this organism is a Gram variable, acid-fast bacterium, with a waxy outer layer, consisting primarily of mycolic acid. The mycolic acid layer allows M. tuberculosis to evade the host immune system (2). The differing pathologies between pulmonary and non-pulmonary forms are due only to the site of infection.

Symptoms of spinal tuberculosis include pain, rigidity, deformity, cold abscess, and eventual paraplegia. Infection of the spine characteristically leads to a gibbus, or a hunchback deformity. The severity of deformity is dependent on the number of vertebrae exhibiting the diagnostic pathology (1). This image, taken in the Museum of Medical History, University of Copenhagen, in Denmark, indicates the abnormality that may arise from this disease. Spinal tuberculosis, or Pott’s disease, begins in the body of the vertebrae, and then quickly spreads to the disk, spinal cord, and eventually to the bloodstream. Once in the circulatory system, the bacteria can spread throughout the body, and cause lesions on various organ surfaces (1).

Potts Disease is usually diagnosed via the Mantoux test, in which purified protein derivatives of M. tuberculosis are injected subcutaneously. After two or three days, the injection site is examined for indications of a delayed-type hypersensitivity reaction. If swelling is present, then the patient has, at some point, been exposed to the pathogen; however, this test does not indicate if the subject is currently infected (http://www.medinfo.ufl.edu/year2/mmid/bms5300/bugs/mycotubr.html). The pathogenesis of the disease allows for relatively simple diagnoses through the use of radiology. Features indicative of spinal tuberculosis include: the narrowing of the intervertebral disc space, which may lead to the destruction and eventual collapse of the vertebral bodies. A calcified abscess may also appear as a shadow on radiological plates (1).

The first step in treating Pott’s disease is to assign the patient to strict bed rest; a plaster shell, covering the torso, may be used to reduce further damage to the spinal cord (1). The primary antibiotics used to combat all tuberculosis infections are rifampin, iosniazid, pyrazinamide, and strepromycin. These drugs are taken in various combinations for up to one year (http://www.medinfo.ufl.edu/year2/mmid/bms5300/bugs/mycotubr.html). If the patient does not show improvement when immobilized and given antibiotics, several surgeries may be employed. These surgeries all have the same basic outcome; portions of, or even complete vertebrae may be removed, in order to decrease pressure on the spinal cord (2).

References

1. Natarajan, M. and N. Mayilvahanan. 2002. Text Book of Orthopaedics and Traumatology – Fifth Edition. M.N.Orthopaedic Hospital: Chennai, India. http://www.bonetumour.org/book/APTEXT/chapter5/ch5_sub2.html.
2. Todar, K. 2002. Tuberculosis in Todar’s Online Textbook of Bacteriology. Todar, University of Wisconsin: Madison, Wisconsin. http://www.textbookofbacteriology.net/tuberculosis.html.

Legend written by:
Joseph Piper
Colorado State University
Fort Collins, Colorado