Electric stimulation may help stroke victims swallow

NEW YORK (Reuters Health) - Tiny electric shocks to the throat may help stroke victims overcome disabling swallowing difficulties, a small British study suggests.

Up to three-fourths of people suffering strokes are left drooling or choking on foods and drinks because brain areas involved in swallowing have been wiped out. Many never recover, and some require a feeding tube.

“Improving swallowing in patients with stroke is likely to have one of the highest impacts on their quality of life,” Dr. Shaheen Hamdy of the University of Manchester, who led the new research, told Reuters Health in an e-mail.

Hamdy is studying whether stimulating nerves in the throat with small electrical jolts can somehow jump-start the areas of the brain damaged by the stroke.

In his new report, published in the journal Gastroenterology, he tested the idea both in stroke victims with swallowing difficulties and in healthy people who had their brains stimulated with a magnetic field to mimic a stroke.

First, the 28 stroke patients had a small tube inserted into their throats. Hamdy’s team then randomly assigned half of the patients to receive electrical shocks--mild enough that they weren’t uncomfortable--for 10 minutes on three consecutive days. The other half had the tube inserted with no current.

A few days later the researchers used X-rays to track how liquid went down the patients’ throats as they swallowed.

About two-thirds of the patients choked on the liquid before getting shocked. After the electric stimulation, that percentage fell to about a quarter. There was no improvement among those who didn’t get shocked.

Swallowing also became easier after stimulation, and the patients left the hospital an average of five days earlier.

However, Hamdy emphasized that the study was small and preliminary, and that not all patients improved. “This is not a panacea,” he said.

But he added that if the findings are confirmed in the larger study he is currently working on, the treatment could benefit a lot of patients.

“The technology is fairly easy to deliver, quick to apply and requires little or no compliance from the patient,” he said. “This makes it eminently suited to stroke patients.”

Today, most treatment consists of modifying a stroke victim’s diet or teaching the patient different ways of chewing. But only a minority of patients benefit from such exercises, experts say. Those who don’t end up with a high risk of developing pneumonia, because foreign particles fall into their lungs when they choke.

While the new technology might potentially benefit these patients, some experts say it faces significant hurdles.

“In terms of practicality, I can’t see this being something you run out and do on patients,” said Giselle Mann, who has worked with swallowing disorders and rehabilitation for some 25 years.

Mann, of the University of Florida, said she had been a research subject herself in one trial and thought the insertion of the throat tube was uncomfortable, if not exactly painful. Frail, elderly people -- or their families -- may not be ready to embrace such an invasive treatment after going through the ordeals of a stroke.

“Swallowing a 3.2-millimeter catheter is no mean feat for anyone,” Mann said, adding that the small number of people in the study also warrants caution.

Still, she found the prospect of expediting the brain’s recovery after a stroke fascinating. “He might be onto something really exciting here,” she said, referring to Hamdy’s research.

How the process speeds recovery is still murky. In an attempt to understand it better, Hamdy and colleagues produced a virtual “stroke” in 13 healthy people by turning on a magnetic coil placed over their skulls.

Repetitive transcranial magnetic stimulation, or rTMS as this technique is better known, messes with the electrical activity of brain cells and can be used to turn them on or off; although it sounds dramatic, it has no known side effects when used briefly in the lab.

With the magnet, Hamdy’s team slowed the activity in brain areas controlling throat muscles, thus mimicking the effects of a stroke. They found a corresponding decrease in throat muscle activity and in the number of correctly timed swallows. But if the subjects were stimulated electrically with the throat tube, these effects were completely abolished.

Electric stimulation of the throat “seems to act by increasing the size of the regions in the brain controlling swallowing, which might actually be how stroke patients spontaneously recover swallowing anyway,” said Hamdy. “We seem to be accelerating this brain ‘plasticity’ process, with effects in both the damaged and undamaged sides of the brain.”

So far, Hamdy has found no negative side effects of the treatment. His university continues to develop the technology, which it plans to market within two years.

SOURCE: Gastroenterology, online February 4, 2010.