Manifestations of Gastrointestinal Disease in the Child

682 FIRST PRINCIPLES OF GASTROENTEROLOGY
communication disorder between the central nervous system and enteric
nervous system (the “brain-gut axis”). The enteric nervous system, which has
been called the “mini-brain,” communicates with the central nervous system
but also acts autonomously. It has three categories of neurons: sensory
neurons, interneurons and motor neurons, and a library of programs that determine
patterns of gut behavior. The sympathetic and parasympathetic nervous
systems transmit signals between the central nervous system and the gut. Afferent
signals from the viscera will normally result in sensations such as hunger
and satiety but will sometimes result in feelings of pain or nausea. Highamplitude
contractions, luminal distention and inflammation can all produce
painful sensations. It is currently hypothesized that functional abdominal pain,
particularly in IBS may result from visceral hypersensitivity with increased
afferent signals from the gut. Possible triggers for this increase in afferent
signals include preceding infection, trauma and allergy. Developmental and
genetic factors are also likely involved. The central response to these afferent
signals may also be magnified. In this situation even physiologic
sensory input from the gut may be interpreted as discomfort. Stress, anxiety
and depression modify the physiologic state which in turn can alter not only
the perception of pain but also intestinal motor and secretory function.
The morbidity resulting from functional abdominal pain syndrome often
relates more to the individual, family and school responses to the symptoms,
rather than the severity of the symptoms themselves. Because of the potentially
complex interactions between biological, psychological and social factors,
children with functional abdominal pain are best assessed and managed using a
bio-psycho-social model of disease.
1.3 Clinical Evaluation
The history and physical examination are important, not only in evaluation,
but also in the successful management of children with functional gastrointestinal
disorders. A diagnosis of functional abdominal pain can be strongly
considered if a history has been elicited that is typical of functional pain, with
no symptoms suggestive of organic disease, and the physical examination is
normal. Education of the family about the nature of this condition can therefore
often begin at the first visit.
The characteristic pattern of functional abdominal pain includes:
1. Pain is localized in the umbilical to mid-epigastric region, but sometimes
poorly localized and felt all over the abdomen.
2. Pain does not radiate.
3. Pain may vary from mild to so severe that the patient may be pale and
diaphoretic.