This study is a pilot, double-blind, placebo-controlled, randomized trial aiming to compare the effects of transcranial direct current stimulation in Chronic Migraine.

The patients will be randomized into 1 of 3 groups: active tDCS over primary motor cortex, active tDCS over prefrontal cortex, sham tDCS. Each group will receive treatment for 20 minutes a day, 3 days a week for 4 weeks.

Inclusion Criteria:

• patients with a clinical diagnosis of chronic migraine according to the International Classification of Headaches Disorders (ICHD-3 beta) of the International Headache Society, with an established headache history occurring on 15 or more days per month-however, for at least 1 year, instead of only 3 months, as defined in the International Headache Society (IHS) guidelines.

Exclusion Criteria:

• headache attributable to some pathological condition, associated neurologic or neuropsychiatric disease, use of central nervous system modulating drugs, pregnancy, metallic head implants, and use of a cardiac pacemaker.