Motility | Gut Motility Disorders
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Cumming School of Medicine
Food needs to be moved through the gut, to places where it can be broken down (stomach and small intestine), and absorbed (small intestine and colon). Waste needs to be moved out of the body. These movements are caused by muscles in the wall of the gut, and controlled by the enteric nervous system (ENS), with input from the brain though peripheral nerves (vagus and spinal nerves). The ENS also regulates secretion and sensation within the gut. The overall process of moving food, liquids, and waste through the gut is called gastrointestinal motility.

The Enteric Nervous System

The ENS is a self-contained system within the gut with its own reflexes and control of movement. It controls motility, secretion, and sensation. The main "movement" of the gut is called peristalsis, the progressive wave of contraction and relaxation of the muscular gut tube, by which the contents are forced through the system.

Sensations from the gut are typically not perceived most of the time unless pain receptors are stimulated. These receptors are usually activated by stretching of the gut wall (called distension), cramping, or inflammation. Usually when the insult subsides, the pain does as well. In certain cases, silent pain receptors (called nociceptors) are activated that do not “turn off” after the insult has gone away, and the patient is left with a chronic pain situation. The reasons for this happening are not known, but this concept underlies many disorders of hypersensitivity, such as post-infectious Irritable Bowel Syndrome (IBS).

Abnormalities of gut motility, secretion, and sensation can lead to a wide range of diseases and disorders. These disorders can be from damage to nerves, muscle, or both of these ENS components. Very often motility problems may be due to drug side-effects, for example diarrhea from the antibiotic erythromycin which stimulates gut motility, or constipation from narcotics which suppress gut motility. Many motility disorders have no known cause but are very common (such as IBS). Some are less common but can be life-threatening, such as gastroparesis or intestinal pseudo-obstruction.

Gastroparesis (gastro= stomach, paresis=paralyzed) is a severe disorder that leads to poor stomach emptying. It leads to symptoms of nausea, vomiting, abdominal pain, or weight loss. Typically, it is due to damage to the nerves or muscle of the gut. Most causes are related to nerve damage (neuropathy) from diabetes, after major stomach surgery, or for unknown (called idiopathic) reasons.

Treatment focuses mostly on symptom management with antinauseants (usually multiple) and by using drugs to help empty the stomach called prokinetics (usually multiple). In severe cases, Neurostimulation may be used for symptom control. Sometimes feeding tubes are used to bypass the stomach to ensure sufferers can maintain nutrition and hydration.

The outlook for people with gastroparesis is improving due to ongoing research in the field. Our understanding of this disorder has advanced significantly in the last decade, with new medications and treatments under study.

Chronic Intestinal Pseudo-Obstruction (CIPO) is so named because X-rays show what looks like a small bowel obstruction which is not due to a physical blockage. Instead, the gut does not move because of the nerves or muscles do not function properly, thus called a "pseudo" obstruction. Due to this significant damage to the nerves or muscles of the small bowel, the intestine loses its ability to contract and push food and air through the digestive tract. Often the cause is unknown but risk factors include having other nervous system or autoimmune disorders, being bedridden or use of narcotic pain medications.

Symptoms range from slow motility, which causes symptoms like constipation, bloating and abdominal pain, to diarrhea. Diarrhea is more likely to occur if there is also bacterial overgrowth in the small bowel.

Current treatments include prokinetic drugs to increase the motility of the small bowel and antibiotics if bacterial overgrowth is found.

Acid Reflux is also known as gastroesophageal reflux disease or GERD. This is a very common condition with a variety of symptoms that can make a hugely detrimental impact on people's quality of life and productivity.

The three most likely symptoms are

* heartburn after eating

* regurgitation of acidic material with small amounts of undigested food

* pain with swallowing (called odynophagia) or feeling like food is sticking in the esophagus (called dysphagia)

Other symptoms may include chest pain, hypersalivation, and nausea.

It is important to seek prompt medical care when you experience pain or difficulty with swallowing, chest pain, unexplained weight loss, choking or bleeding (including vomiting blood or dark coloured stools) as any of these symptoms can indicate a more serious problem.

GERD is diagnosed based upon symptoms and their response to treatments. For mild symptoms, antacids and non-prescription acid reducing medications can be helpful. Losing weight can reduce symptoms. For some people, avoiding foods that can cause the relaxation of the esophageal sphincter such as caffeine, alcohol, chocolate, peppermint and high fat foods can help as does timing meals and snacks so that you do not eat for at least 3 hours before lying down. When these interventions do not resolve the symptoms and discomfort, your physician may prescribe other drugs such as proton pump inhibitors (PPI) and further assessments.