The association between migraine and epilepsy was established more than a century ago. Both disorders are inter-related in epidemiological, clinical, and genetic studies. Although the pathophysiology underpinning such link remains unknown, there has been increasing evidence for a shared genetic susceptibility to migraine and epilepsy that may alter central excitability in both disorders. A recent neurophysiological study using transcranial magnetic stimulation showed a common feature of cortical excitability changes in migraine and epilepsy. Dr. Chen of Taipei Veterans General Hospital in Taipei, Taiwan, explains the details.