April 26, 2017
Mouen Khashab says that about two thirds of his patients who have had pyloric myotomy report no more gastroparesis symptoms.
The National Institutes of Health estimates that as many as 5 million Americans live with gastroparesis. Johns Hopkins gastroenterologist Mouen Khashab cites a 2008 American Journal of Gastroenterology study stating that diagnoses of gastroparesis have increased by more than 150 percent in the past 20 years.
"It's becoming more common," he says. "We don't know why it's on such a steep rise."
What's more, Khashab says there's no reliable medication or treatment for the condition, in which the stomach cannot empty properly, causing abdominal pain, nausea and vomiting. Ultimately, patients with persistent or chronic gastroparesis can suffer dehydration and malnutrition.
"No one has found a specific cause," explains Khashab, "and the only medication for it has a black-box warning for significant side effects."
Khashab has developed an endoscopic procedure that snips the pyloric sphincter to treat certain sufferers of gastroparesis. He is encouraged by the early results.
In 2012, he and several Johns Hopkins colleagues began testing a metallic mesh stent to treat patients with severe, refractory gastroparesis.
"These were patients whose condition was debilitating," Khashab says.
The endoscopist slides a stent past the stomach and deploys it into the pyloric valve, holding the valve open and allowing nutrition to begin its journey through the intestines. Khashab says the stent was successful more often than not, but that he never meant it as a permanent solution.
"Stents migrate," he says. "Mucosa grows over them. There are all sorts of reasons why it wasn't permanent."
Meanwhile, Khashab and other Johns Hopkins endoscopists were frequently performing another procedure for patients with achalasia. That procedure, called peroral endoscopic myotomy (POEM), involves cutting the lower esophageal sphincter muscle to relieve spasms that prevent it from opening and closing properly. Patients with spastic lower esophageal sphincter muscles have difficulty swallowing, and food stays undigested in the esophagus. A myotomy of that muscle brought many patients relief, prompting Khashab to wonder if gastroparesis patients might enjoy similar benefits.
"It's a sphincter muscle in a different place," he says. "Instead of at the bottom of the esophagus, it's at the bottom of the stomach. I thought it might work."
Khashab did a study on the procedure and found that, in many cases, myotomy did indeed relieve gastroparesis symptoms. He notes that patients whose symptoms abated with the temporary stent therapy were the best candidates for what he now calls G-POEM, or gastric peroral endoscopic myotomy.
"We knew that the cause of their gastroparesis was most likely a spastic pyloric sphincter because, for a while, the stents worked for them," he explains.
Khashab has performed about 30 G-POEM procedures, which he describes as slightly more technically challenging than POEM.
"It's like going from driving a car to driving a truck," he says. "It's the same principle, but it requires a little more skill."
He says the rate at which patients show significant improvement is roughly the same as the pyloric stent, about 80 percent. The difference, of course, is that G-POEM offers a better chance at permanent relief.
Khashab can't say for sure if the patients' gastroparesis is cured, since the procedure is only a few years old. But for patients who have responded to the treatment, the outlook is good.
"About two-thirds of our patients who've experienced relief have reported no more gastroparesis symptoms."