Crohn’s disease is a chronic inflammatory bowel disease (IBD) that is caused by inflammation of the digestive tract that results in severe diarrhoea, fatigue, weight loss and malnutrition. Inflammation can affect any part of the digestive tract from the mouth to the anus.
What causes Crohn’s Disease?
There are many factors that contribute to the disease that can range from genetic predisposition, infection, sensitivity of an individual’s immune system and the environment. 1 in 5 patients have family members who also suffer from the disease.
Inflammation can involve the entire gastrointestinal tract but mostly attacks the ileum and right colon. It can also occur in the small bowel, gastroduodenal region and in the anal regions.
An ulcer develops in the mucosal layer and slowly perforates into deeper tissue layers of the intestine that can lead to intestinal fistulae. Long period of inflammation leads to the classic cobblestone mucosa appearance and leaves scar tissue in areas of inflammation.
Aetiology
Crohn’s disease usually occurs in both males and females between 15 to 30 years and is also common in women between 60 to 70 years of age. in younger patients, the disease usually attacks the ileum, the final and longest segment of the small intestine. On the other hand, older patients are more likely to be diagnosed with colonic Crohn’s disease. Patients with small bowel disease face higher risks of death than those with ileal disease.
Symptoms
Crohn’s disease has a relapsing and remitting course. The characteristic presentation is abdominal pain and diarrhoea.
Active symptoms of disease can include:
- Abdominal pain and cramping
- Nausea and vomiting
- Diarrhoea that cannot be stopped by counter medication
- Fatigue
- Anaemia
- Blood in stools
- Rectal bleeding
- Reduced appetite
- Pain around the anus
- Kidney stones
- Delayed growth in children
- Liver inflammation
- Weight loss and nutritional deficiencies leading to psychological issues
Inflammation may extend deep into the bowel walls and can progress from mild inflammations to an abnormal narrowing of the intestines, known as a stricture, due to scarring of intestinal tissue.
In more severe forms of the disease, these symptoms may be found:
- Granuloma formation
- Perianal fistula that causes pain near the anus
- Classic cobblestone mucosal appearances
- Scarring replaces inflamed areas of the intestine
- Fistulas
- Inflammation of joints and skin
Diagnosis of Crohn’s Disease
Routine laboratory studies are nonspecific and primarily help to facilitate the management for disease.
- Liver function tests
- Stool studies
- Serologic tests
- Inflammatory markers
Imaging studies are also useful to observe for bowel obstruction, fibrosis or pelvic intra-abdominal abscesses to assess severity of disease. These modalities include:
- Barium contrast studies that help to look for perforation or enema in the small bowels
- Abdominal CT scan or ultrasonography
- MRI of the pelvis
Endoscopic visualisation and biopsy are imperative in the diagnosis of Crohn’s disease. Children are recommended to undergo upper gastrointestinal endoscopy, even if they do not appear to have upper gastrointestinal symptoms.
- Colonoscopy
- Small bowel enteroscopy
- Endoscopic biopsy
Complications
Extraintestinal manifestations are other parts of the body that have been affected by the disease that is not part of the gastrointestinal system.
1. Colon Cancer
Colon cancer is a significant complication in patients who have Crohn’s disease of the colon. The risk of colon cancer accumulates over the years, which is why surveillance colonoscopy is recommended every 1 to 3 years.
2. Oral disease
Episcleritis is a condition where the episcleral tissue between the clear mucous membrane of the inner eyelids (conjunctiva) and the white part of the eye (sclera) is inflamed. Patients usually present with irritation and burning in one or both eyes. The middle layer of tissue in the eye may also be inflamed to cause visual problems (Uveitis).
3. Dermatological disease
Erythema nodosum is the most common dermatological complication that results from Crohn’s disease. Red, tender nodules may appear along the limb and can range in different sizes. It is more common in children and majority of patients with erythema nodosum develop arthritis as they age. Other skin diseases include psoriasis, alopecia (hair loss) and Crohn’s disease of the vulva and penis.
4. Arthritis
Arthritis is the most common musculoskeletal disease that presents in a quarter of children affected and usually involved the legs and arms. In adults, the disease commonly attacks the knee and small joints when the disease is active.
5. Liver Complications
Primary sclerosing cholangitis may occur in severe cases where there is progressive liver damage leading to cirrhosis. Portal vein thrombosis and pancreatitis are also two other more common manifestations of Crohn’s disease.
Treatment of Crohn’s Disease
Crohn’s disease does not have a cure. Treatment is targeted at maintaining the function of the gastrointestinal tract with minimal toxicity. Most symptoms are treated with antidiarrheal agents, bile acid sequestrants and antibiotics.
Mild cases can be treated with oral mesalamine and 5-asminoaslicyclic acid (5-ASA) and immunomodulators such as mercaptopurine, azathioprine and steroids. Nutritional therapy is also essential, especially in children, to maximise nutritional intake and prevent growth failure.
Severe cases that have led to the formation of fistulas can be treated with biologics. Biologics are special immunoglobulins that help to stop white blood cells (lymphocytes) from travelling to the small intestine to destroy healthy tissue. These include anti-TNF agents such as Infliximab. Anti-TNFs are also used in patients who may be resistant to steroids.
In patients who have developed abscess and fistulas, surgery is the only modality to salvage disease. This usually involves re-sectioning of the affected bowel and drainage of septic pockets of tissue.
Conclusion
Crohn’s disease is a chronic inflammatory autoimmune condition that can be managed with proper medical and surgical therapy.
