Spinal tuberculosis or Pott's disease

 

Tuberculosis is a highly communicable disease caused by the bacterium, Mycobacterium tuberculosis. Tuberculosis (TB) is most common in developing countries and death because of TB is one among the top-10 causes of death worldwide. The prevalence of this disease has increased in developing nations partially as a result of the spread of AIDS in the last few decades.  

The lungs are the primarily affected organs by TB but can spread to other parts of the body. When TB spreads, it’s referred to as (EPTB) extrapulmonary tuberculosis. Around 15% of patients with pulmonary tuberculosis will have extrapulmonary involvement. The spine- the thoracic spine, in particular, is the most common extrapulmonary site to be infected by TB. Spinal TB is a dangerous form of skeletal TB because it is associated with a neurologic deficit due to compression of the adjacent neural structures and cause significant spinal deformity.

Pott’s disease is the slow hematogenous spread (spread through the blood) of tuberculosis to the neighboring sites, particularly the spine.  The infections spread from one vertebra into the intervertebral disc space of other vertibrae the severity increases. The disc remains in normal condition when only 1 vertebra is affected. When two successive vertebral bones are affected, the disc (which is devoid of blood vessels) stops getting the nutrients through blood and collapses completely. A phenomenon referred to as caseous necrosis is observed in these cases, wherein the disc tissue dies. This results in three phenomena-

• Narrowing of the vertebral space

• Vertebral collapse

• Spinal damage

 TB of the spine can cause the destruction of the bone tissue that finally ends up in the development of kyphotic or kyphoscoliotic disfigurement and possible compression of nerve roots with the collapse of the vertebrae.

Spinal canal can narrow due to the protrusion of granulation tissue, lesions like cold abscesses developed in the course of the TB infection, or because of direct infiltration.

Spinal tuberculosis affects the vertebrae and spreads to adjacent spinal structures, resulting in osteomyelitis, and arthritis in several vertebrae

What causes spinal tuberculosis?

Spinal TB occurs once you contract tuberculosis and it spreads outside of the lungs. Tuberculosis is spread from one person to another person through the air. After one contracts tuberculosis the bacterium can travel through the blood from the lungs or lymph nodes into the bones, spine, or joints. Bone TB mainly begins within the middle of the long bones and vertebrae which are rich in blood supply. Bone tuberculosis is difficult to diagnose and may lead to severe problems if left untreated.

What does the TB of the spine look like?

The symptoms of tuberculosis of the bone are not easy to diagnose until it’s far advanced. Bone TB and especially spinal Tuberculosis is challenging to diagnose because it’s painless in the early stages, and therefore one may not exhibit any symptoms, onset of symptoms of tuberculous spondylitis is more insidious than pyogenic infection. When bone TB is diagnosed, signs and symptoms are very advanced.

Symptoms of patients with spinal TB may or may not experience normal symptoms of tuberculosis, which include:

Chronic illness, malaise, night sweats, fever, fatigue, weight loss, back pain.

Sometimes the disease could be dormant within the lungs and spread without the patient knowing that they had tuberculosis, there are some symptoms to look out for once a patient has contracted bone TB:

• Severe back pain

• Swelling

• Stiffness

• Abscesses

When tuberculosis in the bone is more advanced, some dangerous symptoms include:

• Neurological complications

• Paraplegia/paralysis

• Limb-shortening in children

• Bone deformities

Late symptoms that occur after significant bony destruction and deformity which can be made out by physical examination are

• Kyphotic deformity (angular deformity due to the destruction of vertebral bodies),

• Neurological deficits seen in patients with Pott’s disease,

• Mechanical pressure on the cord due to granulation tissue, by an abscess, tubercular debris or caseous tissue,

• Mechanical instability like a subluxation or dislocation,

• Paraplegia with severe deformity from healed disease,

• Stenosis from ossification adjacent to severe kyphosis.

How is Pott’s disease diagnosed and treated?

For the right detection of Pott’s disease, a detailed diagnosis of both the respiratory manifestations and also the joint ailments is extremely necessary. For the detection of Tuberculosis, the subsequent diagnostic tests are preferable-

• Chest X-ray (to examine the lungs)

• Sputum cultures (to detect the presence of bacteria)

• Blood culture

• Tissue biopsy (to check for the chances of cancer)

• Mantoux Tuberculin skin tests ( 84-95% of the patient's results are positive in patients having Pott’s disease)

• Nucleic acid amplification test

In addition to the above tests, the doctors also, advise the patients to go for laboratory examinations in order to detect the extent of the problems-

• Blood tests: An elevated level of C-reactive protein (CRP) and ESR are seen in patients. This is often not necessarily associated with the degree of inflammation since people having very serious inflammation often have normal or near to normal values of CRP and ESR. An ESR of more than 100 mm/h indicates Pott’s disease. Complete blood count (CBC) is usually done so as to detect if leukocytosis has occurred or not.

• BASDAI: the bath ankylosing spondylitis Disease Activity Index (BASDAI) gives a measure of the inflammatory burden of the prevailing diseases.

• Schober’s test: The flexion of the lumbar spine is measured by this test during the preliminary physical examination.

The radiographs of the spine yield these results-

• Collapse of the vertebral body

• Osteoporosis of the vertebral endplates

• Destruction of the intervertebral discs

• Fusiform paravertebral shadows (indicates abscess formation)

• Bone lesions

Spinal tuberculosis treatment

Tuberculosis if it’s contracted is preventable, and generally treatable if it’s discovered early. If one has been diagnosed with tuberculosis, it's highly important for them to undergo extensive treatment to completely cure this condition. When tuberculosis is not treated appropriately or if there is any delay in the treatment, it can result in the spreading of the disease to the surrounding tissues. While bone tuberculosis can cause some painful side effects, the damage is typically reversible when treated early with the proper regimen of medicines. In many cases, spinal surgery is necessary, like a laminectomy (where a section of the vertebrae is removed).

When this disease is diagnosed, it's treated with a regimen of medicines, and in severe cases medications is used in addition to surgical intervention. Medications are the primary line of treatment for spinal tuberculosis, the course of treatment can last anywhere from 6–18 months. Treatments which include:

• Anti-tuberculosis medications, like Rifampicin, Isoniazid, Ethambutol, and Pyrazinamide

• Surgery

Tuberculosis of the spine is preventable and treatable. Early diagnosis and management of spinal tuberculosis are very important to prevent serious complications. The accurate imaging modalities like MRI and advanced surgical techniques have made early diagnosis and management of spinal tuberculosis easier.

• Visit your physician if you observe symptoms like a persistent cough, coughing up blood, weight loss, malaise, night sweats, fever, etc.

• Get screened for a latent TB infection in case you are susceptible to the infection like health care workers, I V drug users, people in contact with TB patients, HIV AIDS patients.

• CT scan or MRI to be done to confirm the diagnosis of spinal tuberculosis.

For more information about problems related to the spine contact Dr. Venugopal S.

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