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Pediatric
Gastrointestinal Motility
Gastrointestinal
Motility
Gastrointestinal (GI) motility is the action enabling
the passage of food and waste products through the four
main regions of the digestive system: esophagus, stomach,
small intestine, and large intestine or colon. At each
stage of the digestive process, from chewing and swallowing
through absorption and elimination, the nervous system
sends signals to muscles and other cells in each GI
region to move the contents along in a synchronized
process called peristalsis.
Digestive System Diagram
The four GI regions are separated by special muscles
or sphincters, which regulate the movement of material
from one region to the next. Each region has a special
function in the digestive process, and each has its
own distinct type of motility:
- The
esophagus propels food from the mouth to the stomach,
in a process initiated by voluntary swallowing. The
lower esophageal sphincter (LES) acts as valve, relaxing
during peristaltic contractions following each swallow,
but normally tightly closed to prevent regurgitation
or reflux of stomach contents.
Peptic Stricture
- The
stomach temporarily stores ingested food while solids
are gradually broken down into particles suitable
for entry to the small intestine through the pyloric
sphincter. Liquids move along quickly, while fatty
foods take the longest. Muscular contractions vary
according to the type and amount of food. Most of
an average meal will have left the stomach in two
hours.
Pyloric Antrum
- The
small intestine is where most nutrient absorption
occurs. Muscular contractions continue for several
hours as food is mixed and moved along. Here again,
different foods are processed through at different
rates. For example, high-fiber foods move through
more quickly than high-fat foods. After most of the
contents have entered the large intestine through
the ileocecal valve, a slower series of powerful contractions
continues between meals, especially at night, to clear
residual material from the small intestine.
Ileocecal Valve
- The
large intestine stores the accumulating food residues
while water and salts are absorbed, until stretching
of the rectum by the resulting stool induces relaxation
of the anal sphincter and contents can be voluntarily
discharged. Patterns of contractions in the colon
are influenced by eating the next meal as a new cycle
of digestion begins in the stomach. The bigger the
meal, the more pronounced the response. Between food
and fluid intake, gallons of fluid are dumped into
the large intestine every day, with most water reabsorbed
by the body. Most contractions of the colon are unsynchronized
or non-peristaltic, and residues can remain in the
colon normally for up to 30 hours, which means a lot
of bacteria.
Anorectum
Abnormalities in the structure or function of these
four GI regions at any stage in the digestive process,
or in the systemic reaction to particular foods or invading
microbes, can result in a GI motility disorder.
GI Motility Disorders
Disorders of GI motility in infants and children, as
well as adults, are most often associated with the following
conditions, syndromes, and diseases. Diagnosis and treatment
will vary according to the underlying symptoms, severity,
and GI regions affected.
Motility
Disorders of the Esophagus
An esophageal motility disorder can involve difficulty
swallowing, heartburn, regurgitation of food, reflux,
or painful spasms produced by certain food allergies.
Examples include gastroesophageal reflux disease (GERD),
hiatal hernia, dysphagia, achalasia, and functional
chest pain.
Motility Disorders of the Stomach
There are two general categories of stomach-related
or gastric motility disorders: delayed gastric emptying
(gastroparesis) and rapid gastric emptying (dumping
syndrome), as well as functional dyspepsia.
Motility Disorders of the Small Intestine
Disorders of motility in the small intestine can produce
symptoms of obstruction or blockage, such as bloating,
pain, nausea, and vomiting. Any of these can result
from weak or disorganized contractions caused by a variety
of conditions generally categorized under intestinal
dysmotility and intestinal pseudo-obstruction. When
motility patterns fail to adequately sweep the upper
part of the small intestine, small-bowel bacterial overgrowth
can produce excess gases resulting in diarrhea and bloating.
Motility Disorders of the Large Intestine
Disorders of motility in the large intestine produce
symptoms of either constipation or diarrhea, incontinence,
and dehydration. They may be the result of colitis,
Hirschsprung’s disease, or more commonly any of
a spectrum of other conditions collectively described
as irritable bowel syndrome or the more sever inflammatory
bowel disease.
GI Motility Testing
Symptoms alone cannot always be relied upon for accurate
diagnosis of a particular patient’s motility disorder.
Proper evaluation is important to correctly diagnose
and properly treat a specific condition. Tests of motility
are used to assess and identify abnormal patterns and
physiology, usually with a first look at ruling out
structural problems before proceeding to functional
problems.
For each region of the GI tract, there are different
tests that assess different functions and provide different
information, but the key categories of information provided
by GI Motility testing include:
- Correct
diagnosis of motility disorder
- Guide
for proper treatment
- Patient
prognosis
A
Closer Look
Organs of the Digestive System
Constipation
As food moves through the colon, or large intestine,
water is absorbed and waste products are formed as stool.
Constipation occurs when too much water is absorbed
by the colon or the colon’s contractions are slower
than normal.
Constipation is typically defined as having a bowel
movement less that three times a week and usually involves
difficult or painful elimination of hard and dry stools.
It is a common problem for children, usually temporary
and of minor concern, but severe cases can require treatment
and may be signs of a more serious underlying problem.
Since constipation may make a bowel movement painful,
a child may try to avoid having one. Constipation itself
is a symptom, not a disease.
Symptoms of constipation can include
- straining
and flushing of the face while attempting bowel movement.
- hard
and dry bowel movements
- no
bowel movements at all for several days
- abdominal
cramps and pain
- nausea
- vomiting
- weight
loss
- traces
of stool in the underwear (indicative of a backup
in the rectum)
Common
causes of constipation can include:
- dehydration
- lack
of dietary fiber
- lack
of physical activity
- irritable
bowel syndrome
- certain
medications or overuse of laxatives
- changes
in routine or stress
- ignoring
or avoiding the urge for a bowel movement
- specific
diseases or other problems with the colon, rectum,
or intestinal function, including neurological disorders,
metabolic or endocrine conditions, and other systemic
disorders
Bristol Stool
Treatment depends on age, severity, and ultimate diagnosis.
More dietary fiber (from fruits, vegetables, or whole
grains), improved liquid intake, and better exercise
will often clear up the condition. Laxatives should
only be given to children with a doctor’s approval.
Because constipation can be both a symptom and a cause
of more serious conditions, a physician should be consulted
if episodes last longer than three weeks, normal activities
are impacted, painful tears or hemorrhoids appear, normal
pushing is not effective in expelling stool, or liquid/soft
stool leaks out of the anus.
Cyclic Vomiting Syndrome (CVS)
Cyclic vomiting syndrome (CVS) involves bouts or cycles
of severe nausea and vomiting that last for hours or
even days, alternating with asymptomatic periods. CVS
occurs mostly in children, and has no known cause. Some
histories suggest each episode tends to be similar to
previous ones, starting at about the same time of day,
of similar duration, with the same symptoms at the same
level of intensity. CVS usually starts between the ages
of 3 and 7. In adults, episodes tend to occur less often
than they do in children, but they last longer. Because
other diseases and disorders also cause cycles of vomiting,
many cases of CVS remain undiagnosed or misdiagnosed
until other more common disorders can be ruled out.
There are four phases in CVS:
-
Prodrome Phase signals nausea and vomiting are about
to begin. Often marked by abdominal pain, this phase
can last from a few minutes to several hours. Sometimes
medication can stop an episode in progress. Sometimes
there is no warning.
- Episode
Phase includes nausea, vomiting, inability to eat
or drink, paleness, drowsiness, and exhaustion.
- Recovery
Phase begins when the episode stops, with return of
healthy color, appetite, and energy.
- Symptom-Free
Interval is the period without symptoms.
The most common trigger of a CVS episode is an infection,
but colds, allergies, sinus problems, and the flu can
trigger episodes in some people. Emotional stress or
excitement in children can set off an episode. Certain
foods, eating too much or too little, hot weather, exhaustion,
and motion sickness can also trigger episodes.
The principle symptoms of CVS are severe vomiting, nausea,
and retching or gagging. Other symptoms can include
pallor, exhaustion, and listlessness. Sensitivity to
light, headache, fever, dizziness, diarrhea, and abdominal
pain may also accompany an episode. Sometimes the nausea
and vomiting are so severe that a person appears to
be almost unconscious.
Recurrent vomiting may cause drooling and excessive
thirst, but drinking water usually initiates more vomiting,
although dilution of acid in the vomit may make the
episode less painful. Continuous vomiting can result
in dehydration through loss of water and salts in the
body.
Diagnosis is difficult because there are no specific
tests to identify CVS and it can take time to identify
a pattern or cycle to the vomiting. A doctor will diagnose
CVS by analyzing symptoms and medical history, and by
excluding more common diseases or disorders with similar
symptoms.
There is no cure for CVS, but there are various modes
of treatment. Sometimes it is possible to stop an episode
from starting by taking ibuprofen to relieve abdominal
pain, or using ranitidine or omeprazole to reduce stomach
acid. Once an episode begins, treatment is mainly supportive,
ranging from bed-rest to hospitalization and intravenous
rehydration, even sedation. Symptom-free intervals are
a good time to eliminate or treat known triggers. Because
symptoms and triggers of CVS are similar to migraine
headaches, medications for migraines such as propranol,
cyproheptadine, or amitriptyline can sometimes help.
Complications of severe vomiting can include dehydration,
electrolyte imbalance, peptic esophagitis, hematemesis,
esophageal tearing, stomach bruising, and tooth decay.
Gastroesophageal Reflux Disease (GERD)
When the lower esophageal sphincter (LES) fails to prevent
gastroesophageal reflux (GER) or backing up of stomach
acids and other contents into the esophagus, the lining
of the esophagus can become irritated, even seriously
damaged over time. The most common symptom is heartburn,
which in infants may appear as difficult or painful
swallowing, inconsolable crying, spitting up, and refusal
to eat. Up to one third of babies have GER at some time,
but almost all outgrow it within a year.
Gastroesophageal reflux disease (GERD) is a more serious
form of GER caused by chronic weakening or improper
functioning of the LES.
(for details about GERD see REFLUX
page on this website)
Gastroparesis
Also known as delayed gastric emptying, gastroparesis
is the slowing or stopping of the movement of food through
the digestive tract. In normal digestion, the stomach
contracts to move food into the small intestine in a
process controlled by the vagus nerve. If the nerve
is damaged or the muscles of the stomach and intestines
do not work properly, gastroparesis occurs.
Symptoms of gastroparesis can include:
- heartburn
or gastroesophageal reflux (GER)
- nausea
and vomiting
- fullness
after a few bites of food
- weight
loss and lack of appetite
- bloating
- abnormal
blood glucose levels
- stomach
spasms
Causes of gastroparesis can include:
- diabetes
- gastroesophageal
reflux disease (GERD)
- stomach
surgery
- viral
infection
- medications
such as narcotics and anticholinergics
- smooth
muscle disorders such as scleroderma and amyloidosis
- nervous
systems disorders such as abdominal migraine and Parkinson’s
- metabolic
disorders such as hypothyroidism
Reglan (metoclopramide) stimulates motility of the upper
gastrointestinal tract without stimulating gastric,
biliary, or pancreatic secretions. While its mode of
action is unclear, it seems to sensitize tissues to
the action of acetylcholine. The effect of metoclopramide
on motility is not dependent on intact vagal innervation,
but it can be abolished by anticholinergic drugs.
Gastroenteritis
Gastroenteritis is a general term referring to inflammation
or infection of the GI tract, primarily the stomach
and intestines. It is usually of acute onset, lasting
less than ten days and tend to be self-limiting. If
inflammation is limited to the stomach, it is called
gastritis. If limited to the small intestine, it is
called enteritis.
Symptoms of gastroenteritis can include:
- loss
of appetite
- lethargy
- fever
- diarrhea
- loose
or watery stool
- stomach
cramps
- dehydration
- sleeplessness
- low
fever and headache
- mucous
or blood in the stool
- vomiting
Causes of gastroenteritis can include:
- viral
infection
- bacterial
infection
- parasitic
infection
- poor
feeding in infants
Viruses are responsible for a the majority of cases
of gastroenteritis in children, with rotavirus the most
common of all. Viruses are easily transmitted from person
to person by close contact and inadequate hygiene.
Gastroenteritis can also occur in the form of food poisoning,
with vomiting more likely than diarrhea, or other GI
infections with diarrhea more common than vomiting.
Common bacteria responsible for gastroenteritis include
salmonella, shigella, staphylococcus, campylobacter,
and cryptosporidium. E. coli in contaminated water or
improperly handled raw meat is another common bacterial
agent.
Also known as giardi for the culprit protozoa passed
via the fecal-oral route through personal contact and
contaminated food and water, giardiasis is an increasingly
common cause of gastroenteritis, infecting hundreds
of millions of people worldwide. Day-care environments,
rural settlements, and wilderness areas are typical
reservoirs, but only about a third of infected people
exhibit symptoms.
The principal treatment for gastroenteritis is rehydration
and elimination of sources of infection. Symptoms may
continue for up to a week, with bowel movements returning
to normal a week after that. When symptoms remain severe,
a doctor may prescribe antimicrobial therapy. Sometime
combining an antimicrobial drug and an antimotility
drug seems to be effective more rapidly, but antimotility
agents risk the delay of flushing of toxins for the
intestines. Oral rehydration and a clean environment
remain the preferred treatment for children.
Hirschsprung’s Disease (HD)
Hirschsprung’s disease, also called aganglionic
megacolon, is a disorder of the large intestine and
always develops before birth. The principle symptom
is constipation, but some children with HD cannot have
bowel movements at all, as the stool creates a blockage.
If not treated, stool blockage can lead to more serious
problems of infection and even bursting of the colon.
In a normal intestine, muscles push the stool to the
anus and elimination from the body. Dedicated nerves
cells, or ganglion cells, signal the muscles to push.
A person with HD is born without these nerve cells in
the lower part of the intestine. There is no known cause
for the cells to have ceased growing during fetal development,
but there are genetic implications, even if neither
parent has HD.
Symptoms of HD may show up in early in infancy, when
newborns fail to start normal bowel movements. If the
length of colon affected is short, serious symptoms
may not appear until later in life, but children and
teenagers with HD will always have had problems with
constipation.
Tests for HD can include barium enema, manometry, or
biopsy. Treatment is surgical, in which the diseased
portion of the colon is removed and the remaining healthy
part is attached to the anus by a pull-through operation.
Whether a ileostomy (removal of the entire colon) or
colostomy (removal of part of the colon) is performed,
temporary use of a stoma and bag is sometimes required
until the intestine is healthy enough for reattachment
to the anus.
Nine out of ten children with HD pass stool normally
after a pull-through and lead normal lives. Complications,
particularly with long-segment HD, can include continued
constipation or diarrhea, and recurring infection of
the large intestine (entercolitis).
Inflammatory Bowel Disease (IBD)
Inflammatory bowel disease (IBD) is a group of inflammatory
conditions of the large intestine, and in some cases
the small intestine. It should not be confused with
the less severe inflammatory bowel syndrome (IBS). About
one third of all persons with IBD have onset before
adulthood, with the peak age between 10-30 years. It
does tend to run in families.
The main forms of IBD are Crohn’s disease, which
can affect any part of the GI tract and ulcerative colitis,
which is restricted to the colon and anus. In children,
there are many other forms of IBD, the most common in
young children being bacterial or parasitic infections,
curable by therapy.
Symptoms of IBD include pain, diarrhea, vomiting, and
weight loss. Diagnosis is generally by colonoscopy with
biopsy. Complications include toxic megacolon and bowel
perforation, as well as an increased risk of colorectal
cancer. Flare-ups of some forms of IBD can occur even
after symptoms are successfully controlled by immunosuppression
and steroids.
The number of cases of IBD has increased as the number
of parasitic infections has fallen, and IBD is rare
where parasitic infections are common, so it has been
hypothesized that some forms of IBD may be an autoimmune
response caused by an overactive immune system lacking
traditional parasitic targets.
Irritable Bowel Syndrome (IBS)
Also known as spastic colon, irritable bowel syndrome
is a functional bowel disorder involving abdominal pain
and irregular bowel habits not obviously related to
well-recognized causes or routinely testable abnormalities,
and not to be confused with the more serious IBD.
Medications include stool softeners and laxatives for
IBS constipation or antispasmodics for IBS diarrhea
or cramps.
Some drugs affecting serotonin in the intestines can
help reduce symptoms of IBS by stimulating intestinal
motility. Agonists may help relieve IBS constipation
and antagonists may help relieve IBS diarrhea, but both
classes of drug are problematic for risks and effectiveness,
especially in cases of IBS misdiagnosis.
Phases and Agents of Intestinal Digestion Affecting
Motility
Delivery of Gastric Chyme to Duodenum
Several key hormones and other agents influence gastric
emptying from the stomach to the duodenum of the small
intestine.
Hormones
- Gastrin
is released by the stomach in response to proteins
and acts to increase gastric motility and emptying.
Low levels of stomach acid inhibit gastrin release.
- Epinephrine
(adrenalin) is released from the adrenal medulla during
stress and acts to decrease gastric motility and emptying.
- Secretin
is released from the duodenum and acts to decrease
gastric motility and emptying.
- Gastric
Inhibitory Peptide (GIP) is released from the duodenum
and acts to decrease gastric motility and emptying.
Neurotransmitters
- Acetylcholine
is released via the parasympathetic nervous system
and acts to increase gastric motility and emptying.
- Norepinephrine
is released via the sympathetic nervous system and
acts to decrease gastric motility and emptying.
Other Substances
- Fats
emptied into the duodenum act to decrease gastric
motility and emptying by causing release of GIP.
- Acids
emptied into the duodenum act to decrease gastric
motility and emptying.
Duodenal Phase of Digestion (First Intestinal
Phase)
The pancreas and liver release a variety of hormones
and other agents into the duodenum of the small intestine,
entering through the common bile duct. Imbalances or
disturbances in the absolute or relative levels of these
agents, or dysfunction of their secreting organs, can
affect motility through the small intestine.
Duodenal Release of Hormones
- Secretin
is a peptide hormone triggered in response to acidic
chyme from the stomach, and acts to neutralize acid
levels and counteract blood glucose spikes. It also
has an optimizing effect on CCK.
- Cholesystokinin
(CCK) is a peptide hormone that affects the digestion
of fat, protein, and carbohydrates, and also acts
as a hunger suppressant. It stimulates the release
of pancreatic enzymes, liver bile, the contraction
of the gall bladder, and relaxation of the Oddi’s
sphincter.
Bile Secretion and Release
- Bile
is continuously produced and secreted by the liver.
Stored and concentrated in the gallbladder between
meals, it is released through Oddi’s sphincter
into the duodenum when chyme enters from the stomach.
Bile helps emulsify fats, and is important in the
absorption of fat-soluble vitamins. It further neutralizes
excess stomach acid before it enters the final section
of the small intestine (ileum). Bile salts are also
bactericidal to invading microbes. In the absence
of bile, fats become indigestible and are excreted
in the feces, which can cause problems of motility
and degrade further absorption of nutrients.
Bile Duct
Digestion and Absorption (Second Intestinal
Phase)
The jejunum is the central of the divisions of the small
intestine, lying between the duodenum and the ileum.
This is where the majority of nutrients are digested
and absorbed through the action of numerous enzymes
acting on proteins, fats, and carbohydrates. Imbalances
here can cause disorders of motility as well as inadequate
nutrition.
Divisions of the Small Intestine
Small Intestinal Motility
The small intestine acts to ensure absorption of nutrient
and aboral (away from the mouth) movement of content.
Types of small intestine movements include:
- Segmentation
produces movements of villi in digestion and absorption
- Peristalsis,
or contractile waves move chyme aborally to the large
intestine, sweeping the small intestine clean in 8-10
hours.
Large Intestine and Water Reabsorption
Water and salts are reabsorbed by the walls of the large
intestine, while bacteria (intestinal flora) break down
remaining undigested nutrients. The large intestine
houses over 700 species of bacteria that perform a variety
of functions. A mucus layer protects the large intestine
from colonic bacterial attack. Antibodies produced by
the immune system against normal “friendly”
flora, can also be effective against related pathogens,
but imbalances here can also result in infection-related
problems with motility.
Two major types of intestinal flora include:
- Fermentative
bacteria break down undigested carbohydrates.
- Putrefactive
bacteria break down undigested proteins, releasing
hydrogen sulfide and methane gas.
A balanced diet, effective digestion, and normal motility
promotes fermentative and putrefactive equilibrium.
Large Intestine Motility
The large intestine acts to ensure absorption of fluids
and salts as matter is condensed and stored in the rectum
for normal elimination.
Types of large intestine movements include:
- Segmentation
produces movements of villi in propulsion and absorption.
- Peristaltic
rushes further compact matter aborally 2-3 times a
day.
Links
to key .org and .gov sites
KidsHealth
for Parents
National
Digestive Diseases Information Clearinghouse (NDDIFC)
KidsHealth
for Parents
NDDIFC
Easy-to-Read Publications
NDDIFC
About Kids
International
Foundation for Functional Gastrointestinal Disorders
(IFFGD)
Citations
Gastroenterology
(Journal) April 2006 Rome III (16 citations)
Selected IFFGD publications
Whitehead, W.E. Gastrointestinal Motility Disorders
of the Esophagus and Stomach. IFFGD Brochure 510; 2001.
Jaffin B.W. Esophageal Motility Disorders. IFFGD Fact
Sheet 518; 1998.
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Los Altos Feeding Clinic
2235 Grant Rd. Ste 2
Los Altos, California 94024
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