Non-invasive vagal nerve stimulation in patients with chronic migraine and medication-overuse headache: a 9-month follow-up study

Introduction Medical treatment of patients with Chronic Migraine and Medication-Overuse Headache (CM-MOH) is often challenging. Neuromodulation is emerging as a new therapeutic option for chronic headaches. Gammacore ® is a portable noninvasive stimulator that produces a mild electrical signal transmitted to the vagus nerve through the skin. A recent report suggested that migraine patients experience a reduction in the severity of their headache symptoms with Non-invasive Vagal Nerve Stimulation (nVNS) [1]. The aim of the study was to evaluate the safety and the efficacy of non-invasive vagal nerve stimulation (nVNS) for the treatment of headache attacks in patients with chronic migraine and medication overuse headache (CM/MOH) after a detoxification period. Methods Fifteen CM-MOH patients (1 man, 14 women; mean age ± SD = 49.9 ± 15.8 yrs) were enrolled in the study. Patients underwent a 5-day in-patient detoxification period and were then followed for 9 months. Headache attacks during the detoxification period and in the follow up period were treated with repeated nVNS. The clinical characteristics of headaches were recorded in headache diaries. Results 566 migraine attacks were treated with nVNS during the study. At two-hours, a pain-free response was observed in 165/566 (29.2%). Average initial pain levels was 1.72 ± 0.7 and dropped to 1.2 ± 0.5 at 2 hours (p<0.01), using the 0-3 points scale. A significant response to nVNS was observed in 50% of treated patients. Drug abuse was halted in all the treated patients. Rescue medications were used in 90 (15.9%) of the attacks treated with Gammacore ® . Treatment-related adverse events were frequent but mild (paresthesia, muscular tension, prickling). Discussion and conclusions This is the first study that evaluated treatment with Gammacore ® in patients with CM-MOH. Hence, results must be viewed cautiously. Our findings show that nVNS could be a safe and efficacious treatment. At two- hours, a pain-free response was observed in approximately one third of treated patients. Large controlled clinical trials in order to evaluate the long-term efficacy of this treatment are needed.