GENERAL CHARACTERISTICS
Irritable bowel syndrome, a condition marked by diarrhea, constipation and
abdominal pain, is caused by excessive spasms of the large intestine. (It
is also known as spastic colon, nervous bowel, irritable colon and mucous
colitis.) Irritable bowel syndrome is not considered a disease as such
because there are no organic abnormalities or physical changes. In many
people, however, stress or feelings of anxiety, guilt or resentment seem
to trigger the symptoms, It is probably the most common abdominal
complaint brought to the attention of doctors, affecting one-third to
one-half of all patients who seek relief from gastrointestinal problems.
In addition, many people have irritable bowel syndrome without ever
consulting their doctors about it.
The
condition appears in late adolescence or early adulthood. For unknown
reasons, women are affected about twice as often as men.
SYMPTOMS
The abdominal discomfort of an irritable bowel ranges from sharp,
cramping-like pains to a continuous, dull ache. It is often relieved by a
bowel movement. The lower left part of the abdomen may be tender to the
touch. This abdominal pain usually appears after eating, although no
particular food or type of food can be identified as the cause.
There is
also usually diarrhea, sometimes alternating with constipation. The
diarrhea typically occurs immediately after a meal or when getting up in
the morning, and there is often mucus in the stool. In addition, there may
be other, less definite symptoms, such as fatigue, anxiety and difficulty
in concentrating.
These
symptoms may last for a few days or weeks and then cease for months at a
time. Also, they may recur with varying degrees of intensity, over a long
period.
INTESTINAL MOTILITY
After nutrients have been digested and absorbed in the small intestine,
the waste material is propelled into the large intestine (also called the
colon or bowel) for eventual elimination as a bowel movement. Under normal
circumstances, regular muscular contractions (intestinal motility) move
this waste matter along the five-foot length of the colon and into the
rectum. When the irritable bowel syndrome is present, however, the pattern
of motility becomes disordered by excessive muscular contractions, which
cause the pain, diarrhea and constipation.
It is
not known what causes the overactivity of the intestinal muscle. Emotional
stress is believed to be a factor in a great many cases. Some researchers
think that the syndrome is an allergic response to particular foods. There
also is some evidence that alcohol, caffeine and heavy smoking may worsen
the problem.