A wireless skin patch using electrical stimulation at an intensity lower than pain threshold reduced migraine pain when compared against sham stimulation in a trial of 71 adults with episodic migraine. The findings were published online March 1 in Neurology.
“Our rationale is activation of pain inhibitory centers, via the conditioned pain modulation effect; remote noxious stimuli can exert a generalized analgesic effect,” wrote David Yarnitsky, MD, of the Rambam Healthcare Campus and Technion Faculty of Medicine, Haifa, Israel, and his colleagues.
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The devices were randomized to give a nonpainful sham stimulation at a very low frequency (controls) or a nonpainful active stimulation at one of four levels (active treatment). Patients were asked to place the wireless patch on the arm of their choice, regardless of the location of migraine pain, and activate the device for 20 minutes as soon as possible after a migraine attack began. They were instructed to use their smartphones to adjust the stimulation as appropriate during the treatment time. The stimulations were active programs at 80-120 Hz with pulse widths of 200, 150, 100, and 50 microseconds. The sham stimulation was a 0.1-Hz frequency with 45-microsecond pulses.
Overall, 64% of patients at the top three stimuli levels reduced their pain level by at least half 2 hours after the treatment, compared with 26% of patients using the sham stimulation. Average reductions were 46% for the 200-microsecond stimulus, 48% for 150, and 39% for 100.
In addition, 58% of the patients in the 200-microsecond group with moderate to severe pain at baseline reported reductions to mild or no pain, compared with 24% of sham patients.
Treatment with stimulation within 20 minutes of migraine onset was the most helpful, resulting in a 47% pain reduction, compared with a 25% reduction with delayed treatment, the researchers noted.
No patients reported side effects or adverse events related to the device.
The investigators said that complete 20-minute treatments were obtained for 70% of each of the top three stimuli levels, for 58% of treatments at 50-microsecond pulse widths, and for just 28% of placebo treatments. This low rate of completion of placebo stimuli may be the result of a loss of blinding for some of the sham activations, the investigators acknowledged, but they argued that “it is likely that this fact did not lead to falsely improved results; on the contrary, had those incomplete stimuli periods been completed, it is most likely that sham effectiveness results would have been lower than currently reported, making the results even more distinct.”
The study was funded by Theranica, and Dr. Yarnitsky disclosed serving on the company’s medical advisory board.