Crohn's disease is a chronic inflammatory disease of the intestines. It
primarily causes ulcerations in the small and large intestines, but can affect
the digestive system anywhere between the mouth and the anus. It is named after
the physician who described the disease in a landmark paper written in 1932. It
is also called Morbus Crohn's, Granulomatous enteritis, Regional enteritis, or
Terminal ileitis. The disease is found in equal frequency in men and women, and
usually affects young patients in their teens or early twenties. Once the
disease begins, it tends to be a chronic, recurrent condition with periods of
remission and disease exacerbation. The disease tends to be more common in
relatives of patients with Crohn's disease.
The cause of Crohn's disease is unknown. Some scientists suspect that infection
by certain bacteria, such as strains of mycobacterium, may be the cause of
Crohn's disease. To date, there has been no convincing evidence that the
disease is caused by infection. Crohn's disease is not contagious. Although
diet may affect the symptoms in patients with Crohn's disease, it appears
unlikely that diet is responsible for the onset of the disease.
Currently, Crohn's disease is believed to be related to abnormalities
in the response of the body's immune system to the bowel contents. The body's immune system is composed of cells and proteins that normally
protect the body from infections or other foreign invaders. In normal
individuals, no immune response will be directed against food, bacteria,
and other substances in the intestines. In patients with Crohn's disease,
the immune system seems to react actively to a variety of substances
and/or bacteria in the intestines, causing inflammation, bowel injury,
and ulcerations. This abnormally active immune system is believed to be
genetically inherited. First degree relatives of patients with Crohn's
disease (brothers, sisters, sons and daughters) are more likely to
develop the disease. Furthermore, certain chromosome markers have been
found in patients with Crohn's disease. Chromosomes are components in
the cells where all the genetic information of the body is stored.
The terminal ileum is commonly involved in Crohn's disease.
Since the terminal ileum is located adjacent the appendix,
right-sided abdominal pain and tenderness mimicking appendicitis
is common. The pain of Crohn's disease can also be crampy in nature,
and may reflect bowel obstruction.
Diarrhea is also common. Diarrhea may be a result of a partial bowel
obstruction, excessive growth of bacteria in the small bowel, poor
absorption of nutrients and bile acids and inflammation of the large
intestine. The diarrhea may be bloody and associated with abdominal
pain and cramps.
Rectal bleeding and bloody diarrhea are common. While massive bleeding
(hemorrhage) from Crohn's ulcer is rare, it can occur.
Diseases affecting the anus are common. Up to one third of patients with
Crohn's disease may have diseases involving the anal area. Anal diseases
include tears of the anal tissue (fissures), infections (abscesses)
adjacent to the anus and draining abnormal passages or tubes (fistulae)
between the inside of the anus and the surrounding skin.
Complications of Crohn's disease may be related to the intestinal disease
or occur in areas unrelated to the intestines (extra-intestinal). Intestinal
complications of Crohn's disease include bowel obstruction, bowel perforation,
formation of pus collections (abscesses), fistulae, cancer of the bowel and
intestinal hemorrhage. Extra-intestinal complications include tender, raised,
reddish skin nodules (erythema nodosum) and inflammation of the following
areas; the joints (arthritis) and spine (spondylitis), the eyes (uveitis and
episceritis), the liver (hepatitis), and the bile ducts (sclerosing cholangitis)
that drain the liver.
Progressive scarring and inflammation of the bowel causes narrowing.
Sometimes, obstruction can be acutely caused by the ingestion of
poorly digestible fruit or vegetables that plug the already narrowed
segment of the intestine. Symptoms of obstruction include crampy
abdominal pain, abdominal distention (enlargement), nausea and vomiting.
As the inflammatory ulcer burrows through the bowel wall, it may
tunnel into adjacent structures. If the ulcer tract reaches an
adjacent empty space inside the abdomen, a collection of infected
material (abscess) is formed. Patients with abdominal abscesses may
develop spiking fevers and tender abdominal masses. When the ulcer
burrows into an adjacent organ, a fistula, or tube, is formed. When
a fistula, or tube, develops between the bowel and the bladder, the
patient can develop recurrent urinary infections, and passage of air
and feces in the urine. A fistula can also occur between the intestine
and the skin, leading to the discharge of pus or mucus through a small
painful opening on the skin of the abdomen.
Massive dilatation (opening) of the colon (megacolon) and rupture of
the intestine (perforation) are potentially life-threatening complications.
Both situations generally require surgery. Fortunately, these two
complications are rare.
Recent data suggest that there is an increased risk of cancer of the small
and the large intestines (colon) in patients with long-standing Crohn's
disease. Cancer of the small intestine is very rare.
However, cancer of the colon occurs more frequently than previously thought.
Areas of extra-intestinal complications include the skin, joints, spine,
eyes, liver and bile ducts. Skin lesions include the presence of painful
red raised spots on the legs (erythema nodosum) and an ulcerating skin
condition generally found around the ankles (pyoderma gangrenosa). Painful
red eye conditions (uveitis, episcleritis) can cause visual difficulties.
Active arthritis can cause pain, swelling, and stiffness of the joints of
the extremities. Inflammation of the low back (sacroiliac joint arthritis)
and of the spine (ankylosing spondylitis) can cause pain and stiffness of
the spine. Inflammation of the liver (hepatitis) or bile ducts (primary
sclerosing cholangitis) can also occur. Sclerosing cholangitis causes
narrowing and obstruction of the ducts draining the liver, and can lead
to yellow skin, recurrent bacterial infections, and liver cirrhosis and
failure. Sclerosing cholangitis with liver failure is one of the reasons
a liver transplant is performed.
Symptoms and severity of the disease vary among patients. Patients with
minimal disease activity with mild or no symptoms may not need treatment.
Patients whose disease is in remission (where symptoms are absent) also
may not need treatment. Most patients with Crohn's disease will experience
periodic increases in activity of the disease when symptoms of abdominal
pain, fever, diarrhea, and rectal bleeding worsen. Medications are then
used to bring the active disease into remission. Medications for the
treatment of active Crohn's disease include salicylate preparations,
corticosteroids, antibiotics, and medications that suppress body immunity.
The decision regarding which treatments are used is based on the location
and the severity of the disease. Patients with advanced disease causing
persistent bowel obstruction, abscess, and fistulae may need surgery.
General measures which may help control Crohn's disease include dietary
changes and supplementation. Since fiber is poorly digestible, it can
exacerbate symptoms of partial bowel obstruction. Hence, a low fiber diet
may be recommended, especially in those patients with small bowel disease.
A liquid diet may be of benefit when symptoms are more severe. Intravenous
nutrition or TPN (total peripheral nutrition) may be utilized when it is
felt that total bowel rest is necessary. Supplementation of calcium, folate
and vitamin B12 is helpful when malabsorption of these nutrients is apparent.
The use of antidiarrheal agents and antispasmotics can also help relieve
symptoms of cramps and diarrhea.
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