Crohn's Disease

Crohn's disease

Author: Professor Antoine CORTOT1 Creation Date: September 2001 Update: June 2003

Scientific Editor: Professor Jean-Alain CHAYVIALLE

1Service des maladies de l'appareil digestif, CHRU Hôpital Claude Huriez, Place de Verdun, 59037 Lille Cedex, France. [email protected]

Abstract Key-words Disease name and synonyms Excluded diseases Diagnosis criteria/Definition Differential diagnosis Prevalence Management including treatment Etiology Genetic counseling Antenatal diagnosis Unresolved questions References

Abstract Crohn's disease is one of the two main inflammatory bowel diseases, the other being ulcerative colitis. It is defined as a transmural inflammation of the bowel involving the terminal ileum and right colon preferentially, but also the small bowel, colon, rectum and the perineal area. The main symptoms are diarrhea, abdominal pain, weight loss often accompanied by extra digestive manifestations such as fever, aphtosis, arthralgia, erythema nodosa. Etiology is still unknown. However, Crohn's disease is thought to be the consequence of an hyperactivated intestinal immune system resulting from the action of unknown environemental factors on genetically-determined susceptibility. Its incidence is lower in Southern countries than in Northern countries (1 to 5 /100,000 ) as well as its prevalence (25 to 150 /100,000). The main drugs are salicylates, steroids, immunomodulators. Surgery is often required for treatment of bowel stenosis, abscess, internal fistula, as well as ano-perineal manifestations of the disease. Patients may require either enteral or parenteral nutrition.

Key-words Crohn's disease; inflammatory bowel disease; diarrhea, abdominal pain; weight loss

functional intestinal disorders; Disease name and synonyms irritable bowel syndrome. Crohn's disease (CD); granulomatous colo-ileitis; Diagnosis criteria/Definition regional enteritis. The diagnosis relies on the accumulation of various criteria including clinical, endoscopical, Excluded diseases histological and biological findings. Ulcerative colitis; The clinical manifestations depend on the indeterminate chronic colitis; distribution and severity of the disease, together microscopic colitis; collagenous colitis; with the presence of complications. The most lymphocytic colitis; celiac disease;

Cortot A. Crohn's disease. Orphanet Encyclopedia, June 2003. http://www.orpha.net/data/patho/GB/uk-crohn.pdf 1 common symptoms are: diarrhea, abdominal appearance is normal, and infection. CD pain, rectal bleeding, anorexia, weight loss. histology is characterized by preserved mucosal They depend on the site of the disease (see architecture, a deep inflammatory infiltrate table 1). toward the lamina propria, fissura, and pseudo- tuberculoid granuloma (found in only 20-30 % of Table1 : Frequency of affected site in Crohn patients with CD). disease Site Frequency Radiology Extensive small bowel disease 5% In acute severe colitis, a plain abdominal Ileum only 25% radiograph is sufficient to diagnose the extent Ileocecal 40% and severity of the attack. The colon may dilate Colon only 25% (« toxic megacolon ») to a diameter superior to 8 Miscellaneous (i.e confined to anorectum, oral, 2% cm. The presence of musocal islands indicates gastric) severe inflammation due to detached mucosa. In long-standing CD, the colon may become The main features in patients with small bowel tubular and shortened due to the loss of disease are pain and weight loss. If it mainly haustrations. occurs after meals, it may indicate partial Small bowel enema is now the technique of intestinal obstruction. The prominent features in choice for the barium examination of the small patients with colonic disease are diarrhea and intestine; by his method, the extent of small bleeding. bowel CD could be determined. The main CD may be revealed by surgical complications: features are: thickening and distortion of the complete or partial intestinal occlusion; intra- valvulae conniventes, edema of the wall, ulcers abdominal, pelvic, or perineal abscess, free and fissuring, luminal narrowing and strictures, peritoneal perforation. prestenotic dilatation indicating severe stricture, Extra digestive manifestations may occur in fistulae to other abdominal organs or to the skin. parallel with the digestive symptoms during attacks such as fever, arthralgia, arthritis, buccal Blood tests aphtosis, erythema nodosa, pyoderma Anemia may be present due to blood loss (iron gangrenosum, iritis, episcleritis. deficiency), chronic inflammation, or B12 malabsorption (macrocytic) in CD. Physical examination Hypoalbuminemia suggests severe disease with The main features to look for are: oral aphtosis, denutrition. abdominal tenderness and masses, anal tags, The best markers of inflammation severity in CD fissure and fistulae, nutritional deficiency. An are elevation of the C-reactive protein and important feature in children is growth platelet count. retardation. Anti-saccharomyces cerevisiae antibodies (ASCA) are positive in 50-60% of CD patients Endoscopy while anti-neutrophil polynuclear antibodies Rigid or flexible procto-sigmoidoscopy will (ANCA) are positive in 50-60% of UC patients. establish the diagnosis of Crohn's proctitis. Mild The combination ASCA+/ANCA- has a positive inflammation may consist of erythema, aphtous predictive value for the diagnosis of CD superior ulcers, granularity with increased contact to 90%. bleeding but with intervals of preserved normal mucosa. Differential diagnosis Colonoscopy helps to determine the pattern and Other conditions to consider if there is terminal severity of colonic and terminal ileum ileal or colonic inflammation include: inflammation, and allows biopsies to be Tuberculosis, obtained. Endoscopic features are aphtous Bacterial infection Yersinia (if only the terminal ulcers, deeper ulceration (sometimes spread like ileum is inflamed), "geographical maps"), postinflammatory polyps Parasitic infection including amoebiasis or (which indicate previous severe inflammation), schistosomiasis if the patient has been to or but always accompanied by intervening normal comes from an endemic area, mucosa, which is an important differential Behçet's disase if there are deep punched-out feature between CD and ulcerative colitis . ulcers. Infection can also occur in patients with Biopsies established IBD (Inflammatory bowel disease), Rectal and colonic biopsies should be examined and should be excluded by routine stool culture to find the nature of the inflammation (ulcerative during new acute episodes of diarrheal illness. colitis versus CD), collagenous colitis or microscopic inflammation if macroscopic

Cortot A. Crohn's disease. Orphanet Encyclopedia, June 2003. http://www.orpha.net/data/patho/GB/uk-crohn.pdf 2

Prevalence Its side effects (headache and nausea) occurring It varies a lot depending on the geographic area, in 15 % of patients, are often dose-related. but it is constantly inferior to the prevalence of ulcerative colitis (except in France). It varies Mesalazine or mesalamine from 140/100,000 in Scandinavia, Great Britain, More recent 5-ASA ( called mesalazine or the USA, Canada to 50/100,000 in Southern mesalamine ) compounds was used Europe. In France, the prevalence is estimated They do not contain a sulphur component. They to be 110 /100,000 in the year 2000. are just as effective as sulphasalazine and are better tolerated. Differences between Management including treatment compounds relate to the different mechanisms of mesalamine delivery: Drugs used in CD Asacol® and Rowasa® contain mesalamine coated with a pH-sensitive acrylic polymer called Corticosteroids Eudragit®-S which dissolves at the pH (pH 6-7) Steroids are proved to be effective in acute found in the terminal ileum and colon. attacks of CD. The optimum initial dose of oral Pentasa® is another mesalamine compound that prednisolone for acute episodes of inflammatory is slowly released and composed of bowel disease (IBD) is 1 mg /kg /day in a single microparticles coated with ethylcellulose. They morning dose resulting in a control of symptoms are released throughout the small bowel and in 60-80 % of patients in 2 to 4 weeks of colon. A dose of 3-4 g/day is mildly effective in treatment. Most patients tolerate well short acute episodes when given orally. Rectal courses of oral steroids, even at high doses, preparations are as effective as steroids in acute without major side effects including: weight gain, episodes of procto-sigmoiditis and in some mood swings (insomnia), acne, easy bruising, patients they are more effective. hypertension, adrenal suppression. These The great value of 5-ASA drugs is their ability to effects can be reduced by weaning off the dose maintain remission in CD at a dose of 2-3 g/day, quickly as an acute episode is controlled. Long- specially after surgical resection. term steroid use is associated with increased The 5-ASA drugs are rarely associated with risk of bone necrosis (e.g. femoral head), nephrotoxicity due to interstitial nephritis. osteopenia (with increased risk of vertebral collapse and other fractures). Every attempt Azathioprine and 6-mercaptopurine should be made to conserve bone density in Azathioprine is metabolized to 6-mercaptopurine patients with CD, including preventive treatment in vivo. This drug is very useful for: with oral intake of calcium, vitamin D and - patients who have frequent relapses despite diphosphonates. taking a 5-ASA compound, Around 30 % of treated patients become - patients with chronic active disease, corticodependent, i.e. they are controlled while - patients who are steroid-dependent. under a 15-20 mg dose of prednisolone and It is proved to be effective in 50-60% of patients relapse quickly when it is stopped. Steroids are with CD. not effective in maintaining remission and should The optimum dose of azathioprine is 2 not be used for prolonged periods. mg/kg/day and 1.5 mg/kg/day for 6- mercaptopurine, and at least 2-4 months of New steroids therapy are required for the drug to have its A recent therapeutic approach involves the use maximum effect (up to 6 months in some of steroids rapidly metabolized on first pass patients). through the mucosa or liver. The systemic About 6 % of patients cannot tolerate the drug bioavailability after oral administration of because of nausea or vomiting, flu-like budesonide (the only new steroid currently used) syndrome, drug fever, or pancreatitis. To avoid is about 10 %, which results in reduced steroids leukopenia, a blood count should be done every side effects. Budesonide (9 mg/day) has the 10 days in the first 3 months and every month same action than prednisolone 40 mg/day in the thereafter. Falls in white cell count are reversible treatment of acute CD, with however, longer by stopping the drug. relapses and less side effects. Methotrexate 5-amino salicylic acid (5-ASA) compounds Methotrexate in an anti-metabolite folic-acid inhibitor with both immunosuppressant and anti- Sulphasalazine inflammatory activity and has the same Sulphasalazine is the longest established 5-ASA indications as azathioproprine - 6- compound (dose of 2 g/day). It contains 5-ASA mercaptopurine. Its side effects include nausea, linked to sulphapyridine by an azo bond, which is diarrhea, stomatitis, leukopenia, elevation of liver split by bacteria in the terminal ileum and colon.

Cortot A. Crohn's disease. Orphanet Encyclopedia, June 2003. http://www.orpha.net/data/patho/GB/uk-crohn.pdf 3 function tests, pneumonitis, liver fibrosis (related Etiology to cumulative doses). The dose which has been used in IBD is 25 mg Environmental factors intramuscularly once a week for short courses (12 weeks), followed by 7.5-15 mg orally per Smoking week. Up to 20 % of patients will have side Smoking increases the risk of developing CD effects which prevent its use. The beneficial and doubles the risk of postoperative recurrence, effect of methotrexate is usually apparent within particularly in women. 2 to 4 weeks . Blood counts and liver function tests should Oral contraceptives initially be performed every 10 days the first 3 There may be a slight association between oral months and then every month. The drug should contraceptive use and the development of CD. be avoided when the risk of liver damage is This is insufficient to deny the oral contraceptive increased. It is contraindicated to start a to a patient, unless she/he has had previous pregnancy during the treatment for the future venothrombotic disease. father and mother, since it is a highly teratogenic Infective agents drug. Despite much effort, incontrovertible evidence of Cytokine modulators an infective cause for CD has not emerged. The Tumor necrosis factor alpha (TNF-alpha) most studied agents have been measles virus, antibody (5 mg/kg) treatment has been shown to Mycobacterium paratuberculosis, and E Coli induce remission in two thirds of patients with (endogenous flora). CD resistant to standard therapies after a single Genetic factors infusion. It also induced 60 % improvement of The genetic contribution to the etiology of CD is severe anoperineal lesions after 3 infusions of 5 polygenic in pattern rather than simply mg/kg each. The long-term side effects and Mendelian, it is stronger in CD than ulcerative benefits remain to be determined. colitis. Susceptibility loci on chromosomes 16, Nutritional therapies has been confirmed in different surveys of They may be the main treatment or may be used familial cases of CD leading to the discovery of in combination with drugs or surgery. Inadequate three main mutations on gene NOD 2 in a nutrition is a major cause of weight loss in adults subset of patients with CD. and impaired growth in children and Genetic counseling adolescents. Nutritional supplementation may be There are no established guidelines for (IBD) given orally or via nocturnal nasogastric feeding risk to offspring of affected parents. The relative in children with growth problems or patients risk for a first-degree relative of a patient with CD resistant to standard therapy. to develop CD is 10-15 times higher than the Complete bowel rest by intravenous feeding is one in general population. The lifetime risk to used in severe resistant or complicated diseases children of a parent with IBD ranges between 5 (internal fistula, bowel stenosis). and 10%, half of the risk being reached during So far, there has been no specific daily oral diet the third decade of life. effective in preventing flare up of Crohn's disease after remission. Food intake must be Antenatal diagnosis varied, abundant, the only limits being the not relevant tolerance and the tastes of the patient. Unresolved questions Surgical treatment The main questions are: Surgery in CD is reserved for the complications - the functional implication of the mutations on of the disease or for active disease resistant to gene NOD2 which is recently discovered; treatment. The main indications include: abscess - identification of environmental factors and that cannot be percutaneously drained, intestinal specially infectious agents, either exogenous obstruction, enterocutaneous fistula, a limited or endogenous, playing a role in the segment causing severe symptoms despite pathophysiology of the disease; treatment, perianal infection requiring drainage. - role of stress in CD; Ileostomy or colostomy, most often transitory - assessment of new "biological therapies" but sometimes definitive, may be required. (specially new anti-cytokines ), prebiotics, probiotics, antibiotics, combined treatments; search for new immunomodulators effective in preventing relapses on the long term.

Cortot A. Crohn's disease. Orphanet Encyclopedia, June 2003. http://www.orpha.net/data/patho/GB/uk-crohn.pdf 4

References Rambaud JC. Les maladies Inflammatoires Bayless TM, Hanauer SB. Advanced Therapy of Chroniques de l'intestin. Collection Pathologie Inflammatoty Bowel Disease. B.C. Decker Inc., Science. John Libbey Eurotext, Paris, 1998; 1- Hamilton.London, 2001;1- 670. 178. Lémann M, Modigliani R. Maladies Targan SR, Shanahan F. Inflammatory Bowel Inflammatoires de l'intestin. Progrès en Disease. From bench to bedside. Williams and Hépatogastroenterologie. Doin Initiatives Santé Wilkins Eds. Philadelphia,1994;1-795. éditeurs, Paris, 1998; 1-271.

Cortot A. Crohn's disease. Orphanet Encyclopedia, June 2003. http://www.orpha.net/data/patho/GB/uk-crohn.pdf 5