A chronic inﬂammatory bowel disease which has a protracted, relapsing and remitting course. An autoimmune condition, it may last for several years. There are many similarities with ULCERATIVE COLITIS; sometimes it can be hard to diﬀerentiate between the two conditions. A crucial diﬀerence is that ulcerative colitis is conﬁned to the colon (see INTESTINE), whereas Crohn’s disease can aﬀect any part of the gastrointestinal tract, including the mouth and anus. The sites most commonly aﬀected in Crohn’s disease (in order of frequency) are terminal ILEUM and right side of colon, just the colon, just the ileum and ﬁnally the ileum and JEJUNUM. The whole wall of the aﬀected bowel is oedamatous (see OEDEMA) and thickened, with deep ulcers a characteristic feature. Ulcers may even penetrate the bowel wall, with abscesses and ﬁstulas developing. Another unusual feature is the presence in the aﬀected bowel lining of islands of normal tissue.
Crohn’s disease is rare in the developing world, but in the western world the incidence is increasing and is now 6–7 per 100,000 population. Around 80,000 people in the UK have the disorder with more than 4,000 new cases occurring annually. Commonly Crohn’s disease starts in young adults, but a second incidence surge occurs in people over 70 years of age. Both genetic and environmental factors are implicated in the disease – for example, if one identical twin develops the disease, the second twin stands a high chance of being aﬀected; and 10 per cent of suﬀerers have a close relative with inﬂammatory bowel disease. Among environmental factors are low-residue, high-reﬁned-sugar diets, and smoking.
Symptoms and signs of Crohn’s disease depend on the site aﬀected but include abdominal pain, diarrhoea (sometimes bloody), ANOREXIA, weight loss, lethargy, malaise, ANAEMIA, and sore tongue and lips. An abdominal mass may be present. Complications can be severe, including life-threatening inﬂammation of the colon (which may cause TOXAEMIA), perforation of the colon and the development of ﬁstulae between the bowel and other organs in the abdomen or pelvis. If Crohn’s disease persists for a decade or more there is an increased risk of the victim developing colon cancer. Extensive investigations are usually necessary to diagnose the disease; these include blood tests, bacteriological studies, ENDOSCOPY and biopsy, and barium X-ray examinations.
Treatment As with ulcerative colitis, treatment is aimed primarily at controlling symptoms. Physicians, surgeons, radiologists and dietitians usually adopt a team approach, while counsellors and patient support groups are valuable adjuncts in a disease that is typically lifelong. Drug treatment is aimed at settling the acute phase and preventing relapses. CORTICOSTEROIDS, given locally to the aﬀected gut or orally, are used initially and the eﬀects must be carefully monitored. If steroids do not work, the immunosuppressant agent AZATHIOPRINE should be considered. Antidiarrhoeal drugs may occasionally be helpful but should not be taken during an acute phase. The anti-inﬂammatory drug SULFASALAZINE can be beneﬁcial in mild colitis. A new generation of genetically engineered anti-inﬂammatory drugs is now available, and these selective immunosuppressants may prove of value in the treatment of Crohn’s disease.
Diet is important and professional guidance is advisable. Some patients respond to milk- or wheat-free diets, but the best course for most patients is to eat a well-balanced diet, avoiding items that the suﬀerer knows from experience are poorly tolerated. Of those patients with extensive disease, as many as 80 per cent may require surgery to alleviate symptoms: a section of aﬀected gut may be removed or, as a lifesaving measure, a bowel perforation dealt with.
(See APPENDIX 2: ADDRESSES: SOURCES OF INFORMATION, ADVICE, SUPPORT AND SELFHELP – Colitis; Crohn’s disease.)