Crohn’s disease

Epidemiology:

• Incidence is 5-8 per 100,000 and rising
• Worldwide distribution, but is more common in the West
• Incidence is lower in the non-white races with a particular penchant for Jews

Aetiopathogenesis:

The aetiology is unknown but it is believed that both genetic and environmental influences are important.

Familial: CD is more common amongst relatives than in the general population

Diet: Possible relationship with a high sugar diet

Smoking: Strongly predisposes to and aggravates CD

Infective agent: Both mycobacterium and the measles virus have been loosely associated.

Pathology:

• Chronic inflammatory condition affecting any part of the GIT from the mouth to the anus
• Most commonly affects the terminal ileum and ascending colon (ileocolonic disease)
• ‘Skip lesions’

Macroscopic changes:

• The involved small bowel is usually thickened and narrowed
• Deep ulcers and fissures in the mucosa – cobblestone appearance

Microscopic changes:

• Inflammation is transmural
• Increase in chronic inflammatory cells and lymphoid hyperplasia
• Granulomas present in 50-60% of pts

Clinical features:

Is a remitting and relapsing disease.

There are two distinct peaks:

- 20-40yrs

- >60yrs (mainly colonic disease)

• Diarrhoea (often bloody in colonic disease)
• Abdominal pain (ranging from discomfort to severe colicky pain)
• Weight loss

Constitutional symptoms of:

• Malaise
• Lethargy
• Anorexia
• Nausea
• Vomiting
• Low-grade fever

May present insidiously or acutely.

Crohn’s disease

Examination:

• Aphthous ulceration of the mouth is common

In colonic CD (80%) examination of the anus may show:

• Oedematous skin tags
• Fissures
• Perianal abscesses

Eyes:

• Uveitis
• Episcleritis
• Conjunctivitis

Joints:

• Monoarticular arthritis
• Ankylosing spondylitis
• Sacroiliitis

Skin:

• Erythema nodosum
• Pyoderma gangrenosum

Other:

• Fatty liver
• Kidney stones
• Gallbladder stones

Investigations:

1. Blood tests:

• Normocytic normochromic anaemia of chronic disease is common
• Fe/folate deficiency also occurs
• Raised ESR/CRP/WCC
• Hypoalbuminaemia in severe disease

2. Stool cultures:

3. Small bowel follow-through:

• Shows an asymmetric alteration in the mucosal pattern
• Deep ulceration and areas of narrowing largely confined to the ileum
• ‘Skip lesions’ with normal bowel in between are also seen

4. Colonoscopy:

• Performed if colonic CD is suspected

5. CT scanning:

• Useful in delineating abscesses, masses, thickened bowel wall and mesentery

Differential Dx:

• All chronic diarrhoeas
• Malabsorption
• Malnutrition

Crohn’s disease

Complications:

• Toxic dilatation (more common in colonic CD)
• Obstruction (e.g. strictures)
• Perforation
• Abscesses
• Fistulae

Medical Mx:

Control diarrhoea with:

• Loperamide 2-4mg tid, or
• Codeine phosphate 30-60mg tid

Acute attacks:

• Anti-inflammatory drugs (e.g. prednisolone 30-60mg/daily)
• Fluid/electrolyte correction
• Azathioprine (2mg/kg/daily) is helpful in maintaining the steroid-induced remission

Surgical Mx:

Approx. 80% of pts will require an operation at some time.

Surgery should be avoided as much as possible as recurrence (15% per year) is almost inevitable.

Indications for surgery are:

• Failure of medical mx with acute/chronic symptoms producing ill-health
• Complications
• Failure to grow in children