Tuberculosis (TB)


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Synonyms: Pott's disease of the spine

The usual sites to be involved in spinal tuberculosis are the lower thoracic and upper lumbar vertebrae[1]. The source of infection is usually outside the spine. It is most often spread from the lungs via the blood. There is a combination of osteomyelitis and infective arthritis.

Usually more than one vertebra is involved. The area most affected is the anterior part of the vertebral body adjacent to the subchondral plate. Tuberculosis may spread from that area to adjacent intervertebral discs. In adults, disc disease is secondary to the spread of infection from the vertebral body but in children it can be a primary site, as the disc is vascular in children.

It is the most common place for tuberculosis to affect the skeletal system, although it can affect the hips and knees too. The infection spreads from two adjacent vertebrae into the adjoining disc space. If only one vertebra is affected, the disc is normal; however, if two are involved the disc between them collapses, as it is avascular and cannot receive nutrients. Caseation occurs, with vertebral narrowing and eventually vertebral collapse and spinal damage. A dry soft tissue mass often forms and superinfection is rare.

Epidemiology

  • Spinal tuberculosis is rare in the UK but in developing countries it represents about 50% of musculoskeletal tuberculosis[2].
  • Spinal tuberculosis accounts for around 2% of all cases of tuberculosis and around 15% of extrapulmonary tuberculosis cases[3].
  • Over 90% of tuberculosis occurs in developing countries; however, a global resurgence is also affecting developed countries.
  • India, China, Indonesia, Pakistan and Bangladesh have the largest number of cases but there has been a marked increase in the number of cases in the former Soviet Union and in sub-Saharan Africa in parallel with the spread of HIV.
  • About two thirds of affected patients in developed countries are immigrants[4].

Risk factors

  • Endemic tuberculosis
  • Poor socio-economic conditions
  • HIV infection[2]

Presentation

Tuberculous spinal infections should be suspected in patients with an insidious, progressive history of back pain and in individuals from an endemic area, especially when the thoracic vertebrae are affected and with a pattern of bone destruction with relative disc preservation and paravertebral and epidural soft tissue masses[5].

  • The onset is gradual.
  • Back pain is localised.
  • Fever, night sweats, anorexia and weight loss.
  • Signs may include kyphosis (common) and/or a paravertebral swelling.
  • Affected patients tend to assume a protective, upright, stiff position.
  • If there is neural involvement there will be neurological signs.
  • A psoas abscess may present as a lump in the groin and resemble a hernia:
    • A psoas abscess most often originates from a tuberculous abscess of the lumbar vertebra that tracks from the spine inside the sheath of the psoas muscle.
    • Other causes include extension of renal sepsis and posterior perforation of the bowel.
    • There is a tender swelling below the inguinal ligament and they are usually apyrexial.
    • The condition may be confused with a femoral hernia or enlarged inguinal lymph nodes.
  • Spinal tuberculosis in children needs a particularly high index of suspicion for diagnosis[6].

Differential diagnosis

Investigations

  • Elevated ESR.
  • Strongly positive Mantoux skin test.
  • Spinal X-ray may be normal in early disease, as 50% of the bone mass must be lost for changes to be visible on X-ray. Plain X-ray can show vertebral destruction and narrowed disc space.
  • MRI scanning may demonstrate the extent of spinal compression and can show changes at an early stage. Bone elements visible within the swelling, or abscesses, are strongly suggestive of spinal tuberculosis rather than malignancy.
  • CT scans and nuclear bone scans can also be used but MRI is best to assess risk to the spinal cord.
  • A needle biopsy of bone or synovial tissue is usual. If it shows tubercle bacilli this is diagnostic but usually culture is required. Culture should include mycology.
  • All patients presenting with extrapulmonary tuberculosis should be offered a chest X-ray and, if possible, culture of a spontaneously-produced respiratory sample to exclude or confirm co-existing pulmonary tuberculosis. Site-specific tests to exclude or confirm additional sites of tuberculosis should also be considered[7].

Associated diseases

  • Tuberculosis co-infection with HIV has become common. It is up to 11% in some areas of the UK and over 60% in countries such as Zambia, Zimbabwe and South Africa.
  • In the developed world, the disease is more common in certain sections of society, such as those with alcohol dependency, the undernourished, ethnic minority communities and the elderly.
  • The disease is also more common in patients after gastrectomy for peptic ulcer.

Distribution

  • The most common area affected is T10 to L1.
  • The lower thoracic region is the most common area of involvement at 40-50%, with the lumbar spine in a close second place at 35-45%.
  • The cervical spine accounts for about 10%.

Management

See also the separate Tuberculosis article.

  • Medical treatment is the mainstay but surgical intervention may be required[8].
  • Immobilisation of the spine is usually for two or three months.
  • Surgery is reserved for select cases of progressive deformity or where neurological deficit is not improved by anti-tubercular treatment[9].

Surgical

Most patients affected by spinal tuberculosis can be successfully treated conservatively with chemotherapy, external bracing and prolonged rest. However, kyphotic deformity, spinal instability and neurological deficit are often associated with a conservative approach[10].

  • A Cochrane review found that routine surgery in addition to chemotherapy had not been shown to improve outcome but the problem was that the evidence was poor[11].
  • A study from India suggested that surgery is not mandatory[12].
  • In patients with spinal tuberculosis, referral for surgery should be considered if there is spinal instability or evidence of spinal cord compression[7].
  • Patients who present with a kyphosis of 60° or more (or a kyphosis which is likely to progress) require anterior decompression, posterior shortening, posterior instrumented stabilisation and anterior and posterior bone grafting in the active stage of the disease[13].

Complications

  • Progressive bone destruction leads to vertebral collapse and kyphosis:
    • The spinal canal can be narrowed by abscesses, granulation tissue, or direct dural invasion. This leads to spinal cord compression and neurological signs (including weakness and paralysis).
    • Kyphosis occurs because of collapse in the anterior spine and can be severe.
    • Lesions in the thoracic spine have a greater risk of kyphosis than those in the lumbar spine.
    • Neurological problems can be prevented by early diagnosis and prompt treatment. It can reverse paralysis and minimise disability.
    • A combination of conservative management and surgical decompression gives success in most patients.
    • Late-onset paraplegia is best avoided by prevention of the development of severe kyphosis[13].
    • Patients with tuberculosis of the spine who are likely to have severe kyphosis should have surgery in the active stage of disease.
  • A cold abscess can occur if the infection extends to adjacent ligaments and soft tissues. Abscesses in the lumbar region may descend down the sheath of the psoas to the femoral trigone region and eventually erode into the skin and form sinuses.

Prognosis

  • The progress is slow and lasts for months or even years.
  • Prognosis is better if caught early and modern regimes of chemotherapy are more effective.
  • A study from London showed that diagnosis can be difficult and is often late[4].

Prevention

See also Tuberculosis Prevention and Screening.

  • As for all tuberculosis, BCG vaccination.
  • Improvement of socio-economic conditions.
  • Prevention of HIV and AIDS.

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Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person.

It mainly affects the lungs, but it can affect any part of the body, including the tummy (abdomen) glands, bones and nervous system.

TB is a serious condition, but it can be cured if it's treated with the right antibiotics.


Symptoms of TB

Typical symptoms of TB include:

  • a persistent cough that lasts more than three weeks and usually brings up phlegm, which may be bloody
  • weight loss
  • night sweats
  • high temperature (fever)
  • tiredness and fatigue
  • loss of appetite
  • swellings in the neck

You should see a GP if you have a cough that lasts more than three weeks or you cough up blood.

Read more about the symptoms of TB and diagnosing TB.

What causes TB?

TB is a bacterial infection. TB that affects the lungs (pulmonary TB) is the most contagious type, but it usually only spreads after prolonged exposure to someone with the illness. 

In most healthy people, the body's natural defence against infection and illness (the immune system) kills the bacteria and there are no symptoms.

Sometimes the immune system can't kill the bacteria, but manages to prevent it spreading in the body.

You won't have any symptoms, but the bacteria will remain in your body. This is known as latent TB. People with latent TB aren't infectious to others.

If the immune system fails to kill or contain the infection, it can spread within the lungs or other parts of the body and symptoms will develop within a few weeks or months. This is known as active TB.

Latent TB could develop into an active TB disease at a later date, particularly if your immune system becomes weakened.

Read more about the causes of TB.

Treating TB

With treatment, TB can almost always be cured. A course of antibiotics will usually need to be taken for six months.

Several different antibiotics are used because some forms of TB are resistant to certain antibiotics.

If you're infected with a drug-resistant form of TB, treatment with six or more different medications may be needed.

If you're diagnosed with pulmonary TB, you'll be contagious for about two to three weeks into your course of treatment.

You won't usually need to be isolated during this time, but it's important to take some basic precautions to stop the infection spreading to your family and friends.

You should:

  • stay away from work, school or college until your TB treatment team advises you it's safe to return
  • always cover your mouth when coughing, sneezing or laughing
  • carefully dispose of any used tissues in a sealed plastic bag
  • open windows when possible to ensure a good supply of fresh air in the areas where you spend time
  • avoid sleeping in the same room as other people 

If you're in close contact with someone who has TB, you may have tests to see whether you're also infected. These can include a chest X-rayblood tests, and a skin test called the Mantoux test.

Read more about treating TB.

Vaccination for TB

The BCG vaccine offers protection against TB, and is recommended on the NHS for babies, children and adults under the age of 35 who are considered to be at risk of catching TB.

The BCG vaccine isn't routinely given to anyone over the age of 35 as there's no evidence that it works for people in this age group.

At-risk groups include:

  • children living in areas with high rates of TB
  • people with close family members from countries with high TB rates
  • people going to live and work with local people for more than three months in an area with high rates of TB

If you're a healthcare worker or NHS employee and you come into contact with patients or clinical specimens, you should also have a TB vaccination, irrespective of age, if:

Read more about who should have the BCG vaccine.

Countries with high TB rates

Parts of the world with high rates of TB include:

  • Africa – particularly sub-Saharan Africa (all the African countries south of the Sahara desert) and west Africa
  • southeast Asia – including India, Pakistan, Indonesia and Bangladesh
  • Russia
  • China
  • South America
  • the western Pacific region (to the west of the Pacific Ocean) – including Vietnam, Cambodia and the Philippines 

The World Health Organization (WHO) has produced a world map showing countries with high rates of TB.





References



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