Open Label, 6-month Study for High Frequency and Chronic Migraine,

Inclusion Criteria: 1. Written informed consent must be obtained from the subject in accordance with requirements of the study site's IRB or ethics committee, prior to initiation of any protocol-specified procedures. 2. Subject must be able to read. 3. Male or female subjects, 18 to 75 years of age inclusive. 4. Subject has at least a 1-year history of migraine (with or without aura) consistent with a diagnosis according to ICHD, 3rd edition with the following: * Age of onset prior to 50 years of age * Migraine attacks lasting on average 4-72 hours untreated. * By subject report at least 8 migraine days of moderate or severe intensity per month over the previous 3 months (prior to screening) * Ability to distinguish migraine from non-migraine headache. * No more than 26 headache days of any type per month by subject report. 5. Patients with at least 8 qualified migraine days per month over the three months prior to Screening will be eligible for entry into this study (assessed by historical recall). A migraine attack must last at least 30 minutes. Any use of an acute migraine-specific medication will count as a migraine attack (day). The interval between two qualified migraine days should be at least 24 hours to be counted as distinct migraine attacks. A migraine attack that remits following treatment (or sleep) and recurs within 24 hours will be counted as one migraine attack. 6. Females should be either of non-childbearing potential by reason of surgery, radiation, menopause (one year post onset), or of childbearing potential and practicing a medically acceptable method of contraception (eg, abstinence, a barrier method plus spermicide, or IUD) for at least one month before study randomization and for two months after the end of the study. Pregnant and/or lactating females are excluded. Those women using hormonal contraceptives must also be using an additional approved method of contraception (eg, a barrier method plus spermicide, or IUD) starting with the Baseline Phase and continuing throughout the entire study period. 7. A sub-set of subjects (capped at 30% of total enrolled) on not more than 1 preventive migraine medication may remain on therapy if the dose has been stable for at least 3 months (12 weeks) prior to the observation period and is not expected to change. * Exceptions include onobotulinumtoxinA treatment (wash out = 3 months). * Patients who are able and willing to attend study visits, maintain a headache diary and otherwise comply with s…