Constipation is hard to define due to the broad variety of bowel habits that are believed "normal." In adults, the condition is less than three bowel movements in a one-week period. There are many different causes of constipation like poor dietary habits, dehydration, structural defects, endocrine disorders, obstructing lesions, outlet obstruction, decreased motility and disturbances in Parasympathetic innervation. Disease processes can also cause this condition such as Chagas disease and Hirschsprung's disease as well as intussusception and meconium ileus.
Hirschsprung's disease is a rare disease that is characterized by the absence of mesenteric neurons in the distal colon. Due to the absence of innervation, this portion of the colon continues contraction. The compacted bowel produces a physical obstacle to the passageway of fecal matter and the preceding section of the colon becomes widened. Symptoms are recognized to be the delay in the route of the meconium to more than 48 hours, the in- ability to pass stool without the aid of enemas/suppositories, abdominal distension, and inadequate nutrition. The symptoms are almost always present from birth.
Diagnosis is achieved through barium enema study that demonstrates enlarged segment of the colon followed by a constricted segment. Biopsy confirms the absence of nerve cells in that segment. This defect requires surgical correction.
Intussusception occurs when a part of the bowel folds into another part of the bowel and is pulled along by the peristaltic contractions. In children 3 months to 3 years intestinal obstructions are most commonly caused by an intussusception. Vomiting and episodes of colicky pain characterise this condition. An intussusception can cause a physical obstruction to waste material passing through the gastrointestinal tract. Additionally there may be blood or mucous present in the stool. Most cases present before the patient reaches their first birthday with the highest incidence between five and nine months of age. Diagnosis of this condition is usually achieved by a contrast study although it may be demonstrated on plain film radiography.
Meconium ileus is a condition that is rarely associated with patients who do not have cystic fibrosis. The inspissated meconium becomes lodged in the intestines causing an obstruction. Failure to pass meconium along with vomiting and distension are clinical signs that the infant is being affected by this condition. This condition can be demonstrated by utilizing contrast media to reveal distal ileum containing the inspissated meconium preceded by bowel dilation. Correction of the obstruction can be achieved through enemas such as Gastrografin or Hypaque or surgical removal.
The rectum is essentially an organ designed to sense the volume of waste material it contains. When it becomes full, the pressure signals the intrinsic nervous system to begin evacuation. The stool is then moved through the anal canal by peristaltic contractions. A disruption in the parasympathetic innervation to the colon could result in decreased sensation and impair the bowel's ability to evacuate its contents. Parasympathetic innervation is achieved through the brain stem via the vagus nerve and the S2 and S3 sacra! roots. An upper cervical subluxation may put pressure on the brain stem and alter the function of the vagus nerve.
