(Reuters Health) - When a migraine strikes, patients might one day be able to make the experience less painful by using a smartphone-controlled device to deliver mild electric shocks to their arm, a company-funded experiment suggests.

The experimental gadget, Nerivio Migra, is a patch with a battery, electrodes and a computer chip that can wirelessly communicate with mobile devices. It’s designed to stimulate nerves under the skin in the arm and block pain signals from reaching the brain.

“All stimulation treatments given so far have been in the head,” said lead study author Dr. David Yarnitsky, an advisory board member for Theranica, the company developing the device.

“We worked on stimulation at a far away location, which makes the treatment more convenient and more discrete so people can use it even during working hours without anyone noticing,” Yarnitsky added by email.

The study involved 71 people with episodic migraines who had two to eight attacks a month and had not taken drugs to prevent the episodes for at least two months.

Participants were typically in their mid-to-late 40s and had been experiencing about five migraines a month. Most of them were female, and more than half of them reported experiencing what’s known as aura

Overall, participants had a total of 299 migraines during the study period.

Researchers asked participants to put the device on their upper arm as soon as possible after the start of a migraine and use it for 20 minutes. They were also asked not to take any medicines for migraines for two hours after the start of the episode.

For the experiment, researchers randomly programed the devices to give either placebo stimulation at a very low frequency or deliver one of four levels of active electrical stimulation treatment.

The four active treatment programs were set at a pulse rate of 80 to 120 Hertz (Hz) with pulse widths of 200, 150, 100 and 50. People feel less stimulation at lower pulse widths. At higher pulse widths than this device used, people might feel their muscles contract.

When researchers excluded the lowest pulse width, they found 64 percent of people in the other active treatment groups had at least a 50 percent pain reduction two hours after treatment, compared with 26 percent of people in the placebo group.

At the highest level of stimulation, 58 percent of the people who started out with moderate to severe pain reported little or no pain after treatment. So did 24 percent of people in the placebo group.

The timing of treatment also mattered.

People who started using the device within 20 minutes of the start of a migraine reported average pain reductions of 47 percent, compared to a 25 percent reduction in pain for people starting the device later.

Even though the study’s participants were not told whether they were assigned active or placebo treatment, one limitation of the experiment is that participants often stopped placebo treatments before the recommended 20-minute course of stimulation was done, the authors note in Neurology.

The technology known as transcutaneous electric nerve stimulation (TENS) that was tested in the current study has been examined in other devices for migraine pain for decades, said Dr. Jean Schoenen, a neurology researcher at the University of Liege in Belgium who wasn’t involved in the current experiment.

One shortcoming of the current study is that researchers didn’t examine how long the pain relief lasts beyond two hours, Schoenen said by email.

“Rapid and sustained relief is what patients want,” Schoenen added.

If the device works in larger trials and becomes widely available for migraine patients, it might offer an alternative for people who can’t tolerate migraine drugs or an option patients could try in addition to medication when they don’t get enough pain relief from drugs alone, Schoenen said.

“The percentage of attacks for which TENS is sufficient as sole treatment and allows sustained pain relief remains to be determined,” Schoenen cautioned.

SOURCE: bit.ly/2lsKXgQ Neurology, online March 1, 2017.