Chapter 039. Nausea, Vomiting, and Indigestion (Part 6) pps

Chapter 039. Nausea, Vomiting,
and Indigestion
(Part 6)

Gastric Motor Dysfunction
Disturbed gastric motility is purported to cause acid reflux in some cases of
indigestion. Delayed gastric emptying is also found in 25–50% of functional
dyspeptics. The relation of these defects to symptom induction is uncertain; many
studies show poor correlation between symptom severity and the degree of motor
dysfunction. Impaired gastric fundus relaxation after eating may underlie selected
dyspeptic symptoms like bloating, nausea, and early satiety.
Visceral Afferent Hypersensitivity
Disturbed gastric sensory function is proposed as a pathogenic factor in
functional dyspepsia. Visceral afferent hypersensitivity was first demonstrated in
patients with irritable bowel syndrome who had heightened perception of rectal
balloon inflation without changes in rectal compliance. Similarly, dyspeptic
patients experience discomfort with fundic distention to lower pressures than
healthy controls. Some patients with heartburn exhibit normal esophageal acid
exposure. These individuals with functional heartburn are believed to have
heightened perception of normal esophageal pH.

Other Factors
Helicobacter pylori has a clear etiologic role in peptic ulcer disease, but
ulcers cause a minority of cases of dyspepsia. Infection with H. pylori is
considered to be a minor factor in the genesis of functional dyspepsia. In contrast,
functional dyspepsia is associated with a reduced sense of physical and mental
well-being and is exacerbated by stress, suggesting an important role for
psychological factors. Analgesics cause dyspepsia, while nitrates, calcium channel
blockers, theophylline, and progesterone promote acid reflux. Other exogenous
stimuli that induce acid reflux include ethanol, tobacco, and caffeine via LES
relaxation. Genetic factors may contribute to development of acid reflux.

Differential Diagnosis

Gastroesophageal Reflux Disease
Gastroesophageal reflux disease (GERD) is prevalent in Western society.
Heartburn is reported once monthly by 40% of Americans and daily by 7–10%.
Most cases of heartburn occur because of excess acid reflux; however,
approximately 10% of patients with functional heartburn exhibit normal degrees of
esophageal acid exposure.

Functional Dyspepsia
Nearly 25% of the populace has dyspeptic symptoms at least six times
yearly, but only 10–20% of these individuals present to physicians. Functional
dyspepsia, the cause of symptoms in 60% of dyspeptic patients, is defined as ≥3
months of bothersome postprandial fullness, early satiety, epigastric pain, or
epigastric burning with symptom onset at least 6 months before diagnosis in the
absence of organic cause. Most patients follow a benign course, but a small
number with H. pylori infection or on nonsteroidal anti-inflammatory drugs
(NSAIDs) progress to ulcer formation. As with idiopathic gastroparesis, some
cases of functional dyspepsia result from prior gastrointestinal infection.

Ulcer Disease
In most cases of GERD, there is no destruction of the esophagus. However,
5% of patients develop esophageal ulcers, and some form strictures. Symptoms do
not reliably distinguish nonerosive from erosive or ulcerative esophagitis. Some
15–25% of cases of dyspepsia stem from ulcers of the stomach or duodenum. The
most common causes of ulcer disease are gastric infection with H. pylori and use
of NSAIDs. Other rare causes of gastroduodenal ulcer include Crohn's disease
(Chap. 289) and Zollinger-Ellison syndrome (Chap. 287), a condition resulting
from gastrin overproduction by an endocrine tumor.

Malignancy
Dyspeptic patients often seek care because of fear of cancer. However,
<2% of cases result from gastroesophageal malignancy. Esophagealsquamous cell
carcinoma occurs most often in those with histories of tobacco or ethanol intake.
Other risk factors include prior caustic ingestion, achalasia, and the hereditary
disorder tylosis. Esophageal adenocarcinoma usually complicates long-standing
acid reflux. Between 8 and 20% of GERD patients exhibit intestinal metaplasia of
the esophagus, termed Barrett's metaplasia. This condition predisposes to
esophageal adenocarcinoma (Chap. 87). Gastric malignancies include
adenocarcinoma, which is prevalent in certain Asian societies, and lymphoma.