Crohn’s Disease
Crohn’s disease is one of the two main forms of chronic inflammation
of the bowel (the other being ulcerative colitis). Crohn’s disease
differs from ulcerative colitis in that it can affect any part of the
gut from the mouth to the anal canal, whilst ulcerative colitis solely
affects the large bowel (colon). Crohn’s disease also causes
inflammation through the entire wall of the gut and can lead to the
formation of fistulas (abnormal connections between the bowel and
other organs), colitis affects only the superficial inner lining of
the colon. The most commonly affected regions of the gut in Crohn’s
disease are where the small intestine joins (the terminal ileum) and
around the anal canal however it can have a patchy distribution with
areas of normal gut between disease segments of bowel, these are known
as skip lesions.
The underlying cause of Crohn’s disease is not known. It seems to be
related to an abnormality in the body’s immune system, which leads to
an exaggerated immune response in the wall of the gut. It is possible
that this may be triggered by an underlying abnormality in the
patient’s immunological system itself, a bacterial or viral infection
or a genetic cause, although it is probably an interplay between a
variety of factors. People may be affected at any age, although the
majority are young adults between 16 and 40 years of age.
Crohn’s disease occurs most frequently
in Northern Europe and North America and tends to run in families,
about 20% of those affected have a brother or sister with the
condition and recently a number of genes have been identified that are
associated with Crohn’s disease. One of the major risk factors for
Crohn’s disease is smoking which doubles the risk of developing the
disease. Those who have been diagnosed with Crohn’s disease should be
encouraged to stop smoking to reduce the severity of the disease.
What are the symptoms of Crohn’s
disease?
Although the symptoms and severity of
the condition vary greatly between individuals, common manifestations
include; cramping abdominal pain, diarrhoea, fever, weight loss,
bloating and recurrent infections or pain around the anal canal. Some
patients experience odd symptoms that do not appear to be related to
the intestine, (these are known as extra-colonic manifestations) and
include joint pain, (arthritis), eye problems (iritis) and skin
lesions.
What is the treatment for Crohn’s
disease?
Treatment of Crohn’s disease is predominantly by drugs and is usually
monitored by a specialist gastroenterologist. Surgery has an important
role to play in the management of this condition, but tends to be
reserved for those patients with complicated disease such as those
whose disease is not responding to medical treatment, those with
abscesses or fistulas and those with bowel obstruction. Since there is
no “cure” for Crohn’s disease long term medical treatment and multiple
operations may be required in some patients.
The drugs used in the treatment of
Crohn’s disease tend to be anti-inflammatory such as aminosalicylates
which deliver an aspirin like compound locally to the gut wall. This
has been shown to be effective in reducing active disease and may have
some role in reducing the risk of recurrence following surgical
resection. Steroids such as prednisolone or budesonide have
traditionally been used to reduce inflammation in active Crohn’s
disease and to reduce the chance that it recurs, but side effects such
as osteoporosis, raised blood pressure, diabetes, adrenal suppression
and cataract formation have lead gastroenterologists to try to reduce
their reliance on them.
Immunomodulation therapy with drugs
such as azathioprine and methotrexate are used successfully to reduce
the patient’s steroid requirements. More recently, medication with
antibodies against naturally occurring substances which are involved
in the immune response such as infliximab have also shown great
benefit in treating disease which would otherwise have required
surgery. Newer drugs which act by different mechanisms are constantly
under development and the whole rationale of drug therapy for Crohn’s
disease is changing to become more “aggressive” trying to prevent the
disease in its early stages rather than escalating treatment once it
has already become established.
In addition, surgical techniques have
advanced and laparoscopic resection (key hole surgery) has become the
method of choice for most cases of Crohn’s disease needing an
operation. Close co-operation between your gastroenterologist and
surgeon will ensure that the optimum medical treatment is instituted
and that should surgery be required, it is not delayed for longer than
necessary.
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