Is there a common pharmacological link between migraine and epilepsy?

If Ca2+-entry blocking action is the common mechanism of action of flunarizine in both epilepsy and migraine, other calcium entry blockers (CEB's) should possess anticonvulsant activity and antimigraine drugs should be anticonvulsants. Since spreading depression (SD) is suggested to underlie the aura phase of classical migraine, antimigraine drugs, CEB's and anticonvulsants would be expected to alter SD. Several experiments showed flunarizine to be an effective anticonvulsant; in some conditions, it increased the threshold for SD; it reduced epileptic bursts recorded from brain hippocampus. However, pharmacology of other CEB's and of antimigraine drugs failed to establish a link between anticonvulsant action, actions on SD and on spontaneous epileptic bursts of the hippocampus.