Researchers from the Thomas Jefferson University in Philadelphia, Pennsylvania studied 157 people fitted with a device that periodically sends mild electrical pulses to the occipital nerves that feed up the neck into the rear of the brain.
In 105 of the participants, the device was active for three months, while in the others it was switched off.
Stephen Silberstein and colleagues found that the active device reduced the average number of migraines per month from 22 to 16 - twice the reduction seen when it was switched off, New Scientist reported.
"Presuming the therapy continues to be effective, I would expect the patients it benefits to retain the implant for life," Silberstein said.
The mechanism by which it works remains unknown, he said, but recent research in animals suggests that it reduces concentrations of a pain neurotransmitter in the nerves.
The device was approved a year ago in Europe, but is still awaiting approval in the US.