The term “gastric motility” refers to the movements of the stomach.
Without this motility, it would be much more difficult for the stomach to digest and move food into the intestines.
Understanding gastric motility is crucial when it comes to diagnosing and treating many digestive diseases, including acid reflux.
I spoke to gastric motility and reflux expert Dr. Mark Noar to find out more.
Why do we need gastric motility?
Dr. Mark Noar: The stomach needs gastric motility to empty itself, to propel foods into the intestines.
How does gastric motility work?
Gastric motility is not a simple concept.
Technically, gastric motility refers to the stomach’s contractions or the electrical activity of the stomach.
The stomach’s motility happens thanks to muscles that are stimulated by impulses from nerve cells. For that to work, we need interface cells known as ICCs, short for “interstitial cells of Cajal.”
Motility begins in a pacemaker high in the body of the stomach, just below the fundus. It generates a circular wave around the body of the stomach, that then causes propagation of a longitudinal wave that runs down the body towards the antrum, which is the bottom part of the stomach.
What role does gastric motility play in reflux disease?
Many people look at the lower esophageal sphincter as something that is there to prevent reflux. But the actual role of the lower esophageal sphincter is to promote normal gastric motility.
In order for the stomach to empty itself, it must build up pressure to propel food out into the intestines. It cannot do that if the lower esophageal sphincter is malfunctioning.
This is essentially the same as an engine backfiring. All of the energy goes up into the esophagus, causing reflux. The pressure is supposed to help the stomach to propel the food downward.
So if you have reflux, you can get poor gastric motility.
Does it also work the other way around? Can a problem with gastric motility cause reflux?
In fact, in a percentage of patients, probably upwards of 25%, it’s the gastric motility that causes reflux.
A good example of that is something we call functional outlet obstruction. The stomach looks normal anatomically, but the sphincter at the bottom of the stomach, known as the pylorus, is malfunctioning. It is supposed to open as the stomach contracts to allow food to exit into the intestine. Instead of doing that, the pylorus is staying shut.
This means the stomach is contracting against a closed opening, which then drives up the gastric pressure, overcoming the lower esophageal sphincter’s ability to maintain that pressure; and this results in a reflux event.
If I sum that up in my own words: there is an intimate relationship between reflux and gastric motility. If you have one of those problems, you likely will get the other as well.
Correct. And this has been proven since the 1950s.
That’s why you also have a relationship between gastroparesis and reflux. Gastroparesis causes symptoms like bloating and a feeling of fullness.
Approximately 40 to 45% of reflux patients have gastroparesis.
How do you diagnose a problem with gastric motility?
There are multiple tests, which are complementary. One does not exclude the other.
One test is the gastric emptying scan [read more about it in this interview about gastroparesis].
Another test is the electrogastrography, also known as electrogastrogram, or EGG for short.
During an electrogastrography, we measure the electrical frequencies emitted by the stomach as it contracts.
An EGG helps us to find out why the gastric motility or gastric emptying is abnormal.
How does the EGG work?
We place three small electrodes on the abdomen over crucial points.
What does the electrogastrogram measure?
It measures electrical frequencies that are necessary for the stomach’s contractions. We’ve already mentioned interstitial cells of Cajal. ICCs transmit signals from the nerves to the muscle in the stomach.
Properly functioning ICCs will allow the stomach to contract normally. They will generate a frequency of 3 cycles per minute in measurable electrical activity.
What would an abnormal EGG look like?
Let’s talk about different types of patients.
Diabetes with circulatory problems might lead to the destruction of a patient’s ICC cells, which means the nerves can’t send impulses to the muscles. It would lead to very low or even no 3-cycle per minute activity at all. That’s one way you could get gastric motility problems.
If the ICCs are intact, the question is: do contractions happen in a normal manner? Abnormal contractions might be too slow, frequencies of 1 and 2 cycles per minute, or too fast, frequencies in the 4-15 range, which is called tachygastria.
We might also see signs of outlet obstruction.
To summarize, electrogastrography detects electrical activity that allows us to determine the stomach’s anatomy, and if it is intact, what disorder may be present and how to treat it.
Can you please clarify one thing for me? Whether the stomach is contracting too fast or too slow, can both cause reflux?
The answer to that is “yes.”
Allow me to explain. Reflux can cause abnormalities in the electrical conduction of the stomach, and it can also be caused by electrical abnormalities in the stomach’s functioning.
Okay, so any problem with gastric motility can cause reflux. However, the EGG helps you to narrow down what causes the disturbances?
We talked about many causes of abnormal gastric motility in our other interviews. We also talked about treatment for those causes.
Are there any short-term treatments to fix gastric motility in general? Without knowing what causes the problem?
As a physician and a scientist, I find it difficult to treat gastric motility without knowing what the causes are.
There are things people can do to decrease symptoms of a gastric motility problem. For example, they might get a lot of bloating and nausea following a meal. Or they might feel really full after a small amount of food—this is called early satiety. Eating lower fat foods, smaller quantities and more frequent meals can help.
However, to truly know what to do about gastric motility symptoms, we need to know what disrupts the motility.
This is just the first part of the interview.
Lastly, we review how all those concepts fit together when it comes to curing reflux.