Self-administered, noninvasive vagus nerve stimulation (nVNS) using the gammaCore (electroCore) device is a safe, tolerable and potentially effective treatment option for the prevention of chronic migraine attacks, according to a 59-patient multicenter study (Neurology 2016;87:529-538).
The mechanism of nVNS provides some of the same benefits as deep breathing, yoga or meditation. The gammaCore device delivers low-voltage electrical stimulation (peak of 24 V, max current of 60 mA) to the neck in the vicinity of the vagus nerve via two stainless steel contacts.
“We had a lot of anecdotal information about gammaCore, but it was important to conduct a controlled trial to actually demonstrate that the device works,” said lead investigator Stephen D. Silberstein, MD, FAAN, professor of neurology and director of the Jefferson Headache Center at Thomas Jefferson University, in Philadelphia. “This is a device that enhances natural vagal circuits normally controlled through relaxation.”
The study participants (mean age, 39.2 years; mean headache frequency, 21.5 days per month) completed a one-month baseline phase before being randomly assigned to receive nVNS with the gammaCore device (n=30) or sham treatment (n=29) for an additional two months. This was followed by six months of open-label nVNS treatment for all participants.
The study treatment protocol consisted of placing the stimulator on the right side of the neck, next to the trachea, three times a day. Each session consisted of a pair of two-minute self-administered stimulations, spaced five to 10 minutes apart.
“Patients adjust their own stimulus, so it is not uncomfortable,” said Dr. Silberstein, who has tested the device on himself.
Dr. Silberstein said at the end of the two-month phase, the difference between stimulation and sham treatment was “very close to what was reported in the Botox (onabotulinumtoxinA, Allergan) trial (1.8-day difference) for treating chronic migraine headache.” Patients in this study reported a 1.2-day difference in the reduction in the number of headache days in the nVAS group compared with the sham group (Headache 2010;50:921-936). Dr. Silberstein noted that this finding was not statistically significant but could be if the same results are achieved in a larger sample size.
“If we had 200 patients in each group instead of around 30, with the same results, then those results would be statistically significant,” he said. “We believe the device actually activates brain stem centers that turn pain off.”
Additionally, patients who used gammaCore as directed for six or eight months experienced a more dramatic decrease in headache days: –6.2 and –7.9 days per month, respectively.
“This highlights the need to use the device consistently and the fact that the group that started with the sham [treatment] never caught up with the group that started with the real gammaCore,” Dr. Silberstein said.
As for the safety of nVNS therapy, there were no significant adverse events,” he said. “Treatment was also perfectly tolerable, although most patients experience slight discomfort from their jaw muscle twitching.”
Rates of acute medication use between the two groups were similar, too, which mirrors the onabotulinumtoxinA study, according to Dr. Silberstein.
“I think we are moving from drugs alone to monoclonal antibodies to devices for treating chronic migraine headache,” he said.
Dr. Silberstein said he is not surprised by any of the study results. “The device confirmed what we suspected,” he said. “It was safe, it was tolerable and it works when given time. This is similar to implanted VNS for epilepsy or depression: The longer it is implanted, the better it works.” The gammaCore device is pending FDA approval.
Dr. Silberstein said this device is particularly appealing to patients “who cannot tolerate drugs or drugs [for whom] are contraindicated, like in the elderly, pregnant women and children.
“This would be an ideal device for these people. I would hope gammaCore is approved within the next six months,” he said.
—Bob Kronemyer