Know about extra-pulmonary tuberculosis

Extra-pulmonary tuberculosis refers to disease outside the lungs. It is sometimes confused with non-respiratory disease. Disease of the larynx for example, which is part of the respiratory system, is respiratory but extra-pulmonary. Extra-pulmonary TB may be characterized by swelling of the particular site infected (lymph node), mobility impairment (spine), severe headache and neurological dysfunction especially in case of TB meningitis. Important to note is that extra-pulmonary TB is not accompanied by a cough because it does not occur in the lungs. It is equally important that both the infectious and non-infectious forms of TB are diagnosed and treated as both can be fatal. How infection occursAt the time primary infection occurs, blood or lymphatic spread of tubercle bacilli to parts of the body outside the lung may take place. In the fully immunocompetent host these bacteria are probably destroyed. If some immune deficiency is present, some may concentrate at a particular site where they may lie dormant for months or years before causing disease. Bacteria may be coughed from the lungs and swallowed. By this route they may enter the lymph nodes of the neck or parts of the gastro-intestinal (GI) tract. In the past before milk was routinely pasteurised, cattle infected with M. bovis, the bovine variant of tuberculosis could pass disease to humans who drank infected milk. Transmission by this route would also give rise to gastro-intestinal diseases. The common sites of infection are lymph glands and abscesses particularly around the neck, orthopaedic sites such as bones and joints. The spine is affected in about half such cases. In women uterine disease is probably the most common, while in men the epididymis is the site most frequently affected. Both sexes are affected by renal, ureteric or bladder disease equally. In the abdomen, this may affect the bowel and peritoneum. Other diseases linked to extra-pulmonary TB include meningitis which may be rapidly fatal if not treated in time, pericardium; the outer layer of the heart muscles which causes constriction to the heart may be affected. On the sin it can take a number of forms, most notably lupus vulgaris where changes of the facial skin was supposed to give patients a wolf-like appearance. Tuberculosis meningitis (TBM) may cause a wide variety of symptoms. A single cranial nerve may be affected resulting in double vision. There may be mental confusion developing over days or weeks. If not detected and treated coma may develop. If treated soon enough recovery may be complete but long term sequelae are likely if the treatment is delayed. TBM has the highest mortality of all complications of tuberculosis. Clinical presentation is characteristically chronic with pain and swelling being the principal features. Lymph glands of the neck may develop singly or in chains. They become swollen painful and may have a rubbery texture. They may break down to give abscess formation. These may discharge onto the skin giving a very unsightly combination of swelling and pus around the neck. Bony disease causes pain and swelling of the affected part. Spinal disease may cause paraplegia if enough of the vertebrae are destroyed to cause instability of the spine. Abdominal disease characteristically causes pain and constipation. If advanced it may cause complete obstruction of the bowel. The diagnosis at any site should be confirmed by obtaining specimens for bacteriology wherever possible. This means that fluid aspirated or biopsies taken should be placed in a medium such as saline which will not kill the bacteria. Too often still, biopsy specimens are placed in formalin so that bacteriological confirmation including sensitivity testing cannot be done. Treatment is as for pulmonary disease with isoniazid, rifampicin, pyrazinamide and ethambutol for two months followed by isoniazid and rifampicin for four months, except for central nervous system disease when treatment should be continued for a full year. Steroids may be used in pericardial and meningeal disease. Surgery is usually unnecessary especially where lymph glands and abscess are pesent as long term discharging sinuses may result. Surgery is sometimes necessary in spinal TB where there is instability and may be needed to overcome strictures in gastro-intestinal disease. Occasionally pericardectomy may be required when pericardial disease causes tamponade in case of heart infection due to extra-pulmonary TB. It is surprising how the most destructive lesion can be healed with drug treatment alone. Ends