The purpose of this multi-center, prospective, double-blind, randomized, sham-controlled pilot study is to study feasibility and collect preliminary clinical data related to the safety and clinical benefits of daily use of non-invasive vagal nerve stimulation with the GammaCore device for the prevention of chronic migraine, and to support the development and approval of a larger pivotal study.

Inclusion Criteria:

• Is between the ages of 18 and 65 years.
• Has been previously diagnosed as suffering from migraine, in accordance with the ICHD-2 Classification criteria (2nd), with or without aura.
• Experiences at least 15 headache days per month (over the last 3 months).
• Has age of onset of migraine less than 50 years old.
• Agrees not to use any migraine prevention treatments (including Botox injections) and/or medications (exclusive of medications taken for acute relief of migraine symptoms).
• Is able to provide written Informed Consent
• Agrees to refrain from changing the type or dosage of any prophylactic medications for indications other than chronic migraine that in the opinion of the clinician may interfere with the study

Exclusion Criteria:

• Has a history of aneurysm, intracranial hemorrhage, brain tumors or significant head trauma.
• Has a lesion (including lymphadenopathy), dysaesthesia, previous surgery or abnormal anatomy at the GammaCore treatment site.
• Has known or suspected severe atherosclerotic cardiovascular disease, severe carotid artery disease (e.g. bruits or history of TIA or CVA), congestive heart failure (CHF), known severe coronary artery disease or recent myocardial infarction.
• Has an abnormal baseline ECG (e.g. second and third degree heart block, atrial fibrillation, atrial flutter, recent history of ventricular tachycardia or ventricular fibrillation, or clinically significant premature ventricular contraction)
• Has had a previous bilateral, right, or left cervical vagotomy.
• Has uncontrolled high blood pressure.
• Is currently implanted with an electrical and/or neurostimulator device, including but not limited to cardiac pacemaker or defibrillator, vagal neurostimulator, deep brain stimulator, spinal stimulator, bone growth stimulator, or cochlear implant.
• Has a history of carotid endarterectomy or vascular neck surgery on the right side.
• Has been implanted with metal cervical spine hardware or has a metallic implant near the GammaCore stimulation site.
• Has a recent or repeated history of syncope.
• Has a recent or repeated history of seizure.
• Has a known history or suspicion of substance abuse or addiction.
• Has had a surgery for migraine prevention.
• Has received Botox injections for migraine prevention within the past 6 months.
• Has taken medications for migraine prophylaxis in the previous 30 days.
• In the opinion of the investigator/research staff the subject is incapable of operating the GammaCore device as intended and performing the data collection procedures.
• Is pregnant, nursing, thinking of becoming pregnant in the next 9 months, or of childbearing years and is unwilling to use an accepted form of birth control.
• Is participating in any other therapeutic clinical investigation or has participated in a clinical trial in the preceding 30 days.
• Belongs to a vulnerable population or has any condition such that his or her ability to provide informed consent, comply with follow-up requirements, or provide self-assessments is compromised (e.g., homeless, developmentally disabled, prisoner).
• Is a relative of or an employee of the investigator or the clinical study site.

Randomized population

Up to 8 weeks - duration of the Randomized period