TUBERCULOUS SPONDYLITIS

Marsilah Binti Mohammad Kamarulzaman

112012239

DEFINITION A spinal infection associated with

tuberculosis and characterized by a sharp angulation of the spine where tubercle lesions are present. Also called Pott's disease.

ETIOLOGY Mycobacterium tuberculosis-

extrapulmonary tuberculosis spread via hematogenous or miliary TB.

Predisposing conditions: - Chronic disorders. - Diabetes. - Drug abuse. - Prolonged corticosteroid medication. - AIDS. - Other disorders resulting in reduced

defence mechanisms.

INCIDENCE Bone and soft-tissue tuberculosis

accounts for approximately 10% of extrapulmonary tuberculosis cases and between 1% and 2% of total cases.

Tuberculous spondylitis is the most common manifestation of musculoskeletal tuberculosis, accounting for approximately 40-50% of cases.

Pott Disease is related to socioeconomic factors and historical exposure to the infection.

Male-to-female ratio of 1.5-2:1 In the United States and other

developed countries, Pott disease occurs primarily in adults. In countries with higher rates of Pott disease, involvement in young adults and older children predominates.

PREDILECTION The usual sites to be involved are the

lower thoracic and upper lumbar vertebrae, it is probably secondary to urinary tract tuberculosis through hematogenous route.

The commonest area affected is T10 to L1.

PATHOPHYSIOLOGY

Mycobacterium tuberculosis enters the lung through

inhalation of air that contain bacilli or Mycobacterium bovis transmitted through milk which is not adequately sterilized or

has been contaminated.

Within the lung, the tubercle bacilli incite a granulomatous type of inflammatory reaction.

Phagocytic macrophages engulf the bacilli.

Nevertheless, tubercle bacilli are able to survive

and multiple even in intracellular environment

The turbecle is relatively avascular, its central

portion eventually becomes caseous.

The turbecle may be healed in the form of

fibrosis. Even in healed tubercles, living tubecles tend to persist in dormant

state and are capable reactivation in

immunocompromise patient

Widespread via the blood stream occurs months or

years later, during a period of lowered

immunity.

Granulomatous inflammation is

characterized by slowly progressive bone

destruction in the anterior part of a vertebral body and is accompanied by regional osteoporosis.

Spreading caseation prevents reactive new

bone formation and at the same time renders segments of bone avascular, thereby

producing tuberculous sequestra.

Tuberculous granulation tissue penetrate the thin cortex of the vertebral

body to produce paravertebral abscess.

The infection spreads up and down the spine under the anterior and posterior

longitudinal ligamnets.

Progressive destruction of bone anteriorly and

resultant anterior collapse of the involved vertebral

bodies lead to progressive kyphosis (posterior

angulation)

CLINICAL FEATURES The onset is gradual/slowly. Back pain. 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.

DIAGNOSIS History of previous infection or recent

contact with tuberculosis. The sedimentation rate is elevated. The tuberculin skin test result is

positive.

RADIOGRAPHC EXAMINATION

Osteolytic lesion in the anterior part of a vertebral body.

Regional osteoporosis. Narrowing of the adjacent intervertebral

disc. Extensive anterior destruction,

involvement of other vertebrae. Paravertebral abscess

CONFIRMED DIAGNOSIS Aspiration of paravertebral pus which is

studied microscopically for tubercle bacilli.

Tissue obtained either by closed punch biopsy or open surgical biopsy reveals the typical histological picture of tuberculous infection.

DIFFERENTIAL DIAGNOSIS Pyogenic osteitis of the spine. -Pain and stiffness in the back which

may be of rapid onset. -The causal agent is predominantly

Staphylococcus. The vast majority of cases resolve after systemic administration of the appropriate antibiotic.

TREATMENT Antituberculosis drugs must be continued for

at least 1 year. - Intensive phase treatment (5 or 6 months) Isoniazid 300-400mg Rifampicin 450-600mg Fluoroquinolones 400-600mg - Continuation phase treatment (9 months) Isoniazid & Pyrazinamide 1500mg for 4

½months Isoniazid & Rifampicin for 4 ½ months - Prophylactic phase (3 or 4 months) Isoniazid & Ethambutol 1200mg

Nourishing diet. Immobilisation of the spine is usually for

2 or 3 months. After 1 month of drug therapy and

rest,the spinal lesion is most effectively treated by open operation to evacuate the tuberculous pus, to remove tuberculous sequestra as well as diseased bone.

PREVENTION As for all tuberculosis, BCG vaccination. Improvement of socio-economic

conditions. Prevention of HIV and AIDS.

COMPLICATION Paraplegi (Pott’s paraplegi)- The paraplegi of active disease

develops early- results from extradural pressure or from direct involvement of the spinal cord by tuberculous granulation tissue.

- The paraplegi of healed disease develops late- results from the gradual development of body ridge that impinges on the spinal canal or from progressive fibrosis.

Rupture of thoracic paravertebral abscess into the pleura to produce tuberculous empyema.

In the lumbar region, pus may enter the iliopsoas muscle and spread distally as a psoas abscess. Example of ‘cold abscess’.

- Cold abscesses are defined as having no associated erythema, heat, or tenderness.

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.