IBS is best described as a functional disease. The concept of functional
disease is particularly useful when discussing diseases of the gastrointestinal
tract. The concept applies to the muscular organs of the gastrointestinal
tract; the esophagus, stomach, small intestine, gallbladder, and colon.
What is meant by the term, functional, is that either the muscles of the
organs or the nerves that control the organs are not working normally,
and, as a result, the organs do not function normally. The nerves that
control the organs include not only the nerves that lie within the muscles
of the organs but also the nerves of the spinal cord and brain.
Some gastrointestinal diseases can be seen and diagnosed with the naked
eye, such as ulcers of the stomach. Thus, ulcers can be seen at surgery,
on x-rays, and at endoscopies. Other diseases cannot be seen with the
naked eye but can be seen and diagnosed with the microscope. For example,
celiac disease and collagenous colitis are diagnosed by microscopic examination
of biopsies of the small bowel and colon, respectively. In contrast, gastrointestinal
functional diseases cannot be seen with the naked eye or with the microscope.
In some instances, the abnormal function can be demonstrated by tests,
for example, gastric emptying studies or antro-duodenal motility studies.
However, these tests often are complex, are not widely available, and
do not reliably detect the functional abnormalities. Accordingly, by default,
functional gastrointestinal diseases are those involving the abnormal
function of gastrointestinal organs in which abnormalities cannot be seen
in the organs with either the naked eye or the microscope.
Occasionally, diseases that are thought to be functional are ultimately
found to be associated with abnormalities that can be seen. Then, the
disease moves out of the functional category. An example of this would
be Helicobacter pylori infection of the stomach. Many patients with mild
upper intestinal symptoms who were thought to have abnormal function of
the stomach or intestines have been found to have an infection of the
stomach with Helicobacter pylori. This infection can be diagnosed by seeing
the bacterium and the inflammation (gastritis) it causes under the microscope
. When the patients are treated with antibiotics, the Helicobacter, gastritis,
and symptoms disappear. Thus, recognition of Helicobacter pylori infection
removed some patients' diseases from the functional category.
The distinction between functional disease and non-functional disease
may, in fact, be blurry. Thus, even functional diseases probably have
associated biochemical or molecular abnormalities that ultimately will
be able to be measured. For example, functional diseases of the stomach
and intestines may be shown ultimately to be caused by reduced levels
of normal chemicals within the gastrointestinal organs, the spinal cord,
or the brain. Should a disease that is demonstrated to be due to a reduced
chemical still be considered a functional disease? I think not. In this
theoretical situation, we can't see the abnormality with the naked eye
or the microscope, but we can measure it. If we can measure an associated
or causative abnormality, the disease probably should no longer be considered
functional.
Despite the shortcomings of the term, functional, the concept
of a functional abnormality is useful for approaching many of the symptoms
originating from the muscular organs of the gastrointestinal tract. This
concept applies particularly to those symptoms for which there are no
associated abnormalities that can be seen with the naked eye or the microscope.
While IBS is a major functional disease, it is important
to mention a second major functional disease referred to as dyspepsia,
or functional dyspepsia. The symptoms of dyspepsia are thought to originate
from the upper gastrointestinal tract; the esophagus, stomach, and the
first part of the small intestine. The symptoms include upper abdominal
discomfort, bloating (the subjective sense of abdominal fullness without
objective distension), or objective distension (swelling, or enlargement).
The symptoms may or may not be related to meals. There may be nausea with
or without vomiting and early satiety (a sense of fullness after eating
only a small amount of food).
The study of functional disorders of the gastrointestinal
tract often is categorized by the organ of involvement. Thus, there are
functional disorders of the esophagus, stomach, small intestine, colon,
and gallbladder. The amount of research on functional disorders has been
focused mostly on the esophagus and stomach (such as dyspepsia), perhaps
because these organs are easiest to reach and study. Research into functional
disorders affecting the small intestine and colon (for example, IBS) is
more difficult to conduct and there is less agreement among the research
studies. This probably is a reflection of the complexity of the activities
of the small intestine and colon and the difficulty in studying these
activities. Functional diseases of the gallbladder, like those of the
small intestine and colon, also are more difficult to study.
Most individuals are surprised to learn they are not alone
with symptoms of IBS. In fact, irritable bowel syndrome (IBS) affects
approximately 10-20% of the general population. It is the most common
disease diagnosed by gastroenterologists (doctors who specialize in medical
treatment of disorders of the stomach and intestines) and one of the most
common disorders seen by primary care physicians.
Sometimes irritable bowel syndrome is referred to as spastic
colon, mucous colitis, spastic colitis, nervous stomach, or irritable
colon.
Irritable bowel syndrome, or IBS, is generally classified
as a "functional" disorder. A functional disorder refers to
a disorder or disease where the primary abnormality is an altered physiological
function (the way the body works), rather than an identifiable structural
or biochemical cause. It characterizes a disorder that generally can not
be diagnosed in a traditional way; that is, as an inflammatory, infectious,
or structural abnormality that can be seen by commonly used examination,
x-ray, or blood test.
Irritable bowel syndrome is understood as a multi-faceted
disorder. In people with IBS, symptoms result from what appears to be
a disturbance in the interaction between the gut or intestines, the brain,
and the autonomic nervous system that alters regulation of bowel motility
(motor function) or sensory function.
Irritable bowel syndrome is characterized by a group of
symptoms in which abdominal pain or discomfort is associated with a change
in bowel pattern, such as loose or more frequent bowel movements, diarrhea,
and/or constipation.
Treatment options are available to manage IBS—whether
symptoms are mild, moderate, or severe.
For more information click
here.
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