Drug & Device Development

Gastric electrical stimulation helps improve diabetic gastroparesis

NEW YORK (Reuters Health) - An implanted device that sends electrical current to the stomach helps relieve diabetic gastroparesis, researchers say.

In the 45 patients who participated in the study, the median weekly vomiting frequency went from nearly 20 episodes at baseline to less than 5 after six weeks.

By one year, vomiting episodes were reduced by at least half in nearly 70% of patients, the researchers report in Clinical Gastroenterology and Hepatology published online June 9th. Other symptom and quality of life measures improved as well.

The research was led by Dr. Richard McCallum of Texas Tech University Health Sciences Center at El Paso and sponsored by Medtronic, Inc., the manufacturer of the Enterra Therapy system used in the study. (Medtronic was also involved in study design and data compilation, analysis, and interpretation, according to a disclaimer in the paper.)

The Enterra Therapy system was approved by the U.S. Food and Drug Administration in 2000 for patients with diabetic and idiopathic gastroparesis. It consists of two leads that are sutured into the gastric smooth muscle and connected to a battery that's implanted subcutaneously in the upper abdomen.

For the first six weeks after surgery to implant the devices, all patients had them in the "on" position at a standardized setting (5 mA, 14 Hz, 330 microseconds, cycle on 0.1 sec, cycle off 5 sec).

Then, in the randomized crossover phase of the study, one group of patients had the device turned off for three months, followed by another three months with it turned on, while the other group started with three months "on" followed by three months "off."

After the crossover phase, the investigators continued to follow the patients until 12 months after implantation. Forty-three patients completed the cross-over phase of the study, and 41 completed the full 12 months.

Over the first six weeks after the surgery, patients' median weekly vomiting frequency (WVF) dropped from 19.5 to 4.75. After the full year, the median frequency was 4.25, and 69.4% of patients had reductions of at least 50%.

At the 12-month point, median gastric retention at 4 hours had improved from 46.5% at baseline to 20.5%.

Nausea, early satiety, bloating, postprandial fullness, and epigastric pain were also significantly less frequent and less severe at one year. In addition, the patients had significantly improved scores on the Physical Component Summary and Mental Component Summary of SF-36 questionnaire.

There was no improvement in body mass index, hemoglobin A1c, or hypoglycemic episodes, however.

Strangely, there were no statistically significant differences in symptoms during the crossover phase between patients in the "on" or the "off" state. Dr. McCallum thinks this could be a result of the study design.

"Perhaps when the device is turned on there is some continuing hangover effect that lasts for the next number of months," he told Reuters Health, and "the first six weeks were enough to entrain or brainwash the stomach or the brain."

Future studies, he said, could address this by leaving the device off initially after surgery.

The Enterra Therapy system costs approximately $12,000, Dr. McCallum said, and with surgery the price tag comes to about $20,000 to $25,000. It can be implanted via either laparoscopy or laparotomy.

The study also revealed certain risks of infection and other problems. Over the course of the study there were 15 serious adverse events including three cases that required surgery, one for an infection of the implant site.

Despite these risks, many say the treatment is worth it because it's one of the last resorts for many patients who have tried medications without success. Dr. McCallum said these patients account for up to about 5% of all diabetics.

"This device provides hope to a group of patients that have really given up hope," he said. If patients decrease their vomiting enough, he said, they can become candidates for a kidney transplant.

Dr. John Lipham, a surgeon at the University of Southern California who specializes in the foregut and who was not involved with the study, said he and his colleagues have implanted about 75 to 100 of these devices. "Usually by the time (patients) get to see us ... they've been tried on all the available medications," he told Reuters Health. "This is generally considered the next step."

And in relation to other surgical treatments for gastroparesis, the "device surgery comparably is a small surgery with much less risk associated with it," Dr. Lipham said. "It is a very safe option."

Clin Gastroenterol Hepatol 2010.

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