Crohn’s Disease – Symptoms and Causes

Crohn’s Disease

It was called regional ileitis because the disease was first reported in the terminal ileum. However, today it is called regional enteritis because the disease can occur in jejunum, ileum, colon, oesophagus, etInvolvement of ileum is more common, followed by colon. More common in North America and Northern Europe.

Incidence is 8/100000 population and in UK incidence is 145/100000 population.

Crohn’s Disease Definition:

Crohn’s disease is a chronic transmural inflammatory disease of the gastrointestinal tract of unknown aetiology. It is neither neoplastic nor tuberculous.

Crohn’s Disease Aetiology:

1. Infectious agents: Mycobacterium paratuberculosis and measles virus have been proposed as potential causes of Crohn’s disease. However, it should be noted that antimicrobial therapy has not been effective in eradicating Crohn’s disease (unlike ATT in TB). Also, no immunological reaction has been found.

2. Immunologic factors: Similar to UFocal ischaemia due to autoimmune reaction has also been considered.

3. Genetic factors: Single strongest risk factor for development of Crohn’s is a relative with Crohn’s disease.

• Relatively high incidence is found in Ashkenazi jaws.

4. Smoking: It increases the risk of Crohn’s disease threefold unlike its protective effect against ulcerative colitis.

5. Diet and Crohn’s disease: Increased intake of carbohydrates and diet rich in refined food have been blamed for. Increased intake of animal protein, milk protein and increased ratio of omega-6 to omega-3 polyunsaturated fatty acids have also been blamed.

Pathogenesis of Crohn’s Disease:

Crohn’s Disease Pathology:

• The disease starts in terminal ileum as ulcerations of intestine in about 60% of cases.
• There is extensive inflammatory oedema and mucosal ulcers are present. Fibrotic thickening of the intestine results in hose pipe rigidity of the intestine.

• There are skip areas which are characteristic of Crohn’s disease (segments of intestine are normal in between).
• Mesenteric nodes are enlargeThey can be calcified but do not show any caseation.
• Intense infiltration of mononuclear cells and lymphoid hyperplasia is common.
• As the disease progresses, there is cicatrizing granuloma of the bowel wall. This results in narrowing of lumen causing intestinal obstruction. Caseation is characteristically absent.
• Once inflammation spreads to the serosa, adhesions develop between bowel loops or other structures. Abscesses occur in the mesentery which rupture resulting in internal fistul

Crohn’S Disease Clinical Features:

The disease is often insidious, slowly progressive with a protracted course and commonly affects young adults in the second or third decade of life. Intermittent colicky lower abdominal pain, diarrhea and weight loss are common.

Depending upon symptoms, it can be classified as follows:

Crohn’s disease:

1. Stage of ileocolitis: Clinically, it presents as pain abdomen and mucus in stools. It is seen in younger patients. It may be associated with fever. Presence of pain and tenderness in the right iliac fossa mimics appendicitis. If there is a mass, it may be confused for an appendicular mass.

2. The stage of subacute intestinal obstruction occurs due to stricture of the terminal ileum. Strictures can be multiple. They are not reversible.

3. Stage of fistula formation: It can be enteroenteric or enterocutaneous. Following are the examples of fistulae encountered in Crohn’s disease—ileovesical, ileocolic, ileoileal, ileovaginal, etc.

4. Perianal disease in the form of multiple ulcers in the anorectal region, perianal abscesses, multiple fistulae in ano are much more common than in ulcerative colitis. Repeated infection of anal crypt due to diarrhoea is common.

Crohn’s Disease Extraintestinal Complications:

• Skin: Pyoderma gangrenosum, erythema nodosum
• Joints: Arthritis, ankylosing spondylitis
• Bile duct: Sclerosing cholangitis
• Eyes: Iritis, uveitis
• Nephrotic syndrome
• Pancreatitis
• Amyloidosis
• Crohn’s disease that affects the ileum—increased risk of gallstones. This is due to a decrease in bile acid resorption in the ileum.

Crohn’S Disease Differential Diagnosis:

1. Ulcerative colitis: However, colonic symptoms are more with ulcerative colitis.
2. Tuberculosis: In India, tuberculosis should be considered first and ruled out.
3. Appendicitis: Acute pain in the right iliac fossa can be confused for acute appendicitis. For the benefit of the doubt, the patient can undergo laparotomy. Laparoscopy and appendicectomy will be better.
4. Intestinal obstruction: Other causes of obstruction have to be kept in mind.

Crohn’S Disease Investigations:

1. Small bowel enema: Enteroclysis.
   1. Cobblestone reticulation because of multiple ulcers with islands of normal mucosa in between.
   2. Absence of peristalsis in terminal ileum.
   3. String sign of Kantor is demonstrated in terminal ileum due to narrowing of the lumen.
   4. Multiple strictures and dilated segments in between can be demonstrated.
2. Sigmoidoscopy and colonoscopy may demonstrate inflamed mucosa, which is granular with aphthoid ulcers, which are discrete.
3. Fistulography to localise the internal fistula.
4.  CT scan: It is done to detect thickening of bowel and extraintestinal disease.
5. Remember to investigate the upper GI tract with gastroduodenoscopy and capsule endoscopy.

Crohn’S Disease Treatment:

1. General principles:

• Complete rest, avoid stress and emotions.
• A low residue, high caloric diet such as high protein diet.
• Some patients may require total parenteral nutrition—some at home called home parenteral nutrition.

2. Conservative (medical) treatment is similar to ulcerative colitis.

• Steroids are the mainstay of treatment. They are effective in inducing remission in 70 to 80% of cases.
• Steroids are most effective in treating small intestinal disease. They are anti-inflammatory. They do control diarrhoea, induce remissions. Prednisolone is used for short-term treatment. Long-term use can give rise to toxicity such as immunosuppression, bone loss, delayed wound healing, etc.
• Salazopyrines can be used especially in maintenance cases also.
• Even though salazopyrines and corticosteroids have been beneficial in Crohn’s disease, salazopyrines do not induce remissions. They are used in acute ileocolitis. Steroids can be used for anorectal disease.
• Immunosuppressive therapy using azathioprine and 6-mercaptopurine are also effective.
• They are effective in treatment of colonic disease. The main concern is bone marrow toxicity. 6- mercaptopurines are known to produce pancreatitis.
• Most recent and promising drug is infliximab— a monoclonal antibody to tumour necrosis factor α (TNFα). It mainly helps in closure of fistul It is given intravenously and is used for intestinal and perianal disease.
• Metronidazole has shown some benefit.

3. Surgical treatment: Resection is not the aim of surgery but it may have to be done in cases of obstruction, perforation, intra-abdominal abscesses, internal fistulae, bleeding and malignancies. Depending upon the involvement of the bowel, various resections are possible.

Crohn’s Disease Examples:

1. Stricture—stricturoplasty or resection
2. Ileocaecal resection
3. Colectomy and ileorectal anastomosis
4. If the fistulae are present, they are disconnected from the bowel and excise Comparison of intestinal tuberculosis, ulcerative colitis and Crohn’s disease.

Summary of tubercular ileocolitis, ulcerative colitis and Crohn’s colitis:

Crohn’S Disease Prognosis:

• In spite of various treatment, there is no cure for the disease. About 10–20% patients come with relapses and recurrent symptoms.
• Despite for repeated treatment including surgical procedures, survival is still good as compared to general population without the disease.

A Few Observations in Crohn’s Disease:

• The ileum is the most common site.
• Small bowel alone is affected in 20–30% of the patients.
• Both small bowel and large bowel in 50–60% patients.
• Duodenum, stomach, oesophagus can also be involved.
• Inflammatory cells and mediators of the inflammation such as cytokines, interleukins, tumour necrosis factors produce the inflammatory changes resulting in granuloma.
• Sometimes, very difficult to differentiate clinically and pathologically between tuberculosis and Crohn’s disease.
• Anus is involved in Crohn’s colitis, not in ulcerative colitis.