Dysmotility is where the muscles of the digestive system become impaired and changes in the speed, strength or coordination in the digestive organs occurs. In the normal small intestine, liquefied food and secretions including digestive enzymes are pushed onwards by waves of muscular contraction. When these contractions are impaired, the contents are trapped, and cause distention with symptoms such as bloating, nausea, vomiting and even malnutrition. There are many causes of abnormal intestinal motility. They can be divided into two major groups:
- abnormalities of the muscle of the intestine (myopathy)
- abnormalities in the neural (nerve) control of the muscle (neuropathy)
Some myopathies and neuropathies are familial (ie genetically transferred). In this situation it is common to find many family members of a patient with problems of contractility not only of the intestinal muscle but also of the bladder, the muscles of the eye and even the limbs. These primary causes of intestinal dysmotility are quite rare. More common are the secondary causes of intestinal dysmotility in which a diffuse disorder affecting many systems of the body also involves the intestines. Examples of this include systemic Lupus erythematosus, amyloidosis, neurofibromatosis, Parkinson's disease, diabetes, scleroderma, thyroid disorders, and muscular dystrophies. Certain medications can also cause intestinal dysmotility. Additionally, any disorders that cause inflammation to the intestine can cause significant dysmotility (i.e. radiation therapy, celiac disease).
Symptoms may be absent or trivial. However, some patients have severe recurrent attacks due to functional blockage that can mimic complete intestinal obstruction. This is called "intestinal pseudo-obstruction." In addition, common symptoms include cramps, bloating, pain, nausea and vomiting, especially after eating. Patients who develop bacterial overgrowth because of poor motility may develop diarrhea, while others may be constipated. Associated disorders of motility in other organs such as the esophagus, stomach and colon will produce other symptoms. Patients with severe dysmotility will develop malnutrition because they are unable to eat adequately.
Blood Tests – Blood tests help to assess the degree of malnutrition, anemia and any salt imbalance. They may also make a specific diagnosis such as diabetes, thyroid problems and systemic disorders such as Lupus.
X-ray Studies – X-ray studies (barium) help to delineate the extent of bowel involvement by demonstrating areas of distended intestines, and by excluding mechanical obstruction. This must be done because treatment of pseudo-obstruction and true obstruction are very different.
Motility/Transit Studies – Motility/transit investigations help to define the degree of contractile abnormality as well as propulsive abnormality of the intestines. They are sometimes useful (by assessing the pattern of contraction) in deciding whether a neuropathy or myopathy is present.
Biopsies – Biopsy samples of the intestine are obtained at endoscopy or surgery, and may detect the cause of the dysmotility.
Mechanical obstruction (i.e. blockage) must be excluded before a patient is diagnosed as having pseudo-obstruction or intestinal dysmotility as a cause of their symptoms. Specific treatments are available for some causes of dysmotility, including abnormalities in salt balance and endocrine problems such as thyroid disease.
Unfortunately, many causes of dysmotility cannot be cured, and symptomatic treatment is offered. Medicines can stimulate intestinal motility and help with propulsion of intestinal contents. Dietary modifications are advised. It is important that adequate calories are taken, usually in the form of meal supplements. Patients should avoid gas forming foods, carbonated beverages, and foods that are difficult to digest. Patients may need to be admitted to hospital for intravenous fluids, and decompression of the intestine with a tube placed in the stomach. Occasionally, nutrition will have to be supplied through a vein.
When only a short segment of the small intestine is involved, surgical resection may be appropriate. However, patients must be carefully selected as surgery can lead to scarring (adhesions) within the abdominal cavity, with further disturbance of intestinal motility.